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It carries the loads of sheer stress and cabin pressure. Figure. 9 shows the combined features mentioned above. The semi-monocoque structure is considered.

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MODELING

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By James

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January

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Monitor

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DEPARTMENT COLLEGE OLD

OF COMPUTER

SCIENCE

OF SCIENCES

DOMINION

NORFOLK,

UNIVERSITY

VIRGINIA

GEOMETRIC

23529

MODELING

FOR

COMPUTER

By James

L. Schwing,

Progress For

the

period

ended

Aeronautics

Langley

and

Research

Hampton,

1, 1993

Grant

Lawrence

Submitted

Administration

23681-0001

NCCI-99

F. Rowell,

SSD-Vehicle

Space

Center

Virginia

Under Research

Analysis

Technical

Monitor

Branch

by the

Old Dominion P.O. Box 6369 Norfolk,

January

for

National

April

Investigator

Report

Prepared

V

Principal

Virginia

1993

University

Research

23508-0369

Foundation

AIDED

DESIGN

Geometric

Modeling

Progress

for Computer

Report

Aided

- January

Design

1993

1. Introduction

Over

the

past

implementation carried

several

software

out under

this grant

(VAB)

of NASA

resulted

in the

development

the

Research

interactive Tool

sonnel

of

puter

and

aided

the last

year,

execution

surface the

and

of the

the

and grant

The

Solid

among

these

Environment

it is the purpose

particularly

has

Aerospace

the

design

work

This

Modeling

by EASIE,

and

Analysis

Corp.

Primary

of smactural

parallel

to design

vehicles.

Vigyan

studies.

In addition, areas

grant

of the Vehicle

and

provided

implementation,

representation

investigators

design

tools

in the

members

Corp.

SMART,

of this

of aerospace

with

and

and Execution.

development

goal

design

Sciences

tool,

consultation

of the per-

and

in the areas

algorithm of com-

algorithms.

specifically

proposed

to consider

the

areas.

Provide general consulting codes; in particular, design Establish perform Research Build

and

Integration

geometric

primary

out jointly

packages

modeling

to provide

the

Computer

of several

software

design,

During following

grant

carried

Langley,

integration

Software

this

development,

the

been

in the conceptual

has been

geometric

and

for Application

it has

to be used

Branch

arel

years,

on the use and development of aerospace structural and implement a new Structures Module for SMART.

a database interface for POST that allows data consistency checks for the model. the possibility

a prototype

of providing

X-Window

interface

a general

data

for EASIE.

easier integrity

definition checker

of data for EASIE.

analysis and

helps

-2-

Develop transfer

methods for the creation of smoother, "faired" surfaces for SMART to allow the of SMART geometry to structural grid generation programs and other analysis

programs

requiring

Develop

algorithms

This report papers.

Copies

of this report ence

surfaces

articles

to a number

of the

Master's

they

appear

provides

ally provides

initial

user interface

that

paper

to otherwise

have

obtain.

and

computing.

presentations been

appended

The other

are therefore

and journal to the

papers

not included

and

end

confer-

here.

Codes

designers

property

makes

it easy

proven

to be of interest

with a rapid prototyping

analysis. to learn

it has become

tools

In addition, and use.

a priority

into the areas of aerodynamic

Recently,

a new design

concerned

engineering team

and

to number team

effort

have

phase.

tion plans

for the

gone

groups

the type

analysis.

at NASA,

with the purpose

through

has

a formal

These notably

collected

review

process.

extensions

to SMART.

of the

work

centered

on taking

the

The

personnel

structural

implementation on this grant

analysis

portion

plans aided

of the

and

approved

continuing

in the development

codes

including

analysis

that

the

HISAIR

requirements synthesized The

design

system on

have project. from

all

by

the

team

is

requirements

to the of the

consulting

is

analysis

enhancements

and

for these

first

engineered

of the SMART

documents here

a carefully

of soliciting

were

and addition-

of vehicle

the capabilities

and su'uctural

requirements

capability

design

and developing

debugging

The

SMART

Given

to extend

of other

was formed

groups.

since

completing

A major documents

conference

an AIAA

of Structural

mass

in VAB,

presently

and

and distributed

projects,

in the open literature

conceptual

support

design

requirements.

Extensions

SMART

conducted

of Master's

may be difficult

as cited

exacting

use of parallel

projects

2. Use and Development

2.1 SMART

more

for the efficient

refers

since

to meet

coding

and

implementa-

on the general

-3developmentof tion

of these

transfer

system

Corporation. developed

data

improvements

A portion

project

"Surface Generation Vehicle Fuselages", ence, 1992.

In addition, implementation This

has

several

included design

the primary

structure

includes

of

the

a lifting-body

task

between

needs

to be changed

following

James

interior

Computer

structure

por-

Sciences

for fuselages,

was

to support element

in the VAB.

has been

the development

involved

these

converting At present

of

been

focused

conceptual

design

and

level

a discrete

stage

wing

sections the vehicle

hardcopy

is changing

design.

and

in

of the priThe

model

multi-bubble with

and

involved

model

vehicle.

and internal

from

codes

element

launch

design

aerospace

analysis

of a finite

a two

on the

linear

tanks. and

the analytic

quamodel

changes.

and other

Robinson.

stage

has

structural Some

codes

and analysis

of the primary

results

have

been

provided

of this work,

resulted

through in the

publication.

"Structural tem", J.C. and

to meet

grant

underway

the sections.

on these

by Mr.

of finite

fuselage,

scaling

Consultation

tools

configuration

dratic

grant

design

this

first

of this model

this

under

air-breathing

Development

to develop

with

for the final

Consulting

aided

currently

to programmers

code

Operations Applied ato Structural Support of Aerospace ODU Master's Project, Department of Computer Sci-

the use of a number

studies

given

that used

research

of computer

Of these, mary

Analysis

continuing

been

of the actual

by Ms. S. Schwartz.

and Editing S. Schwartz,

Structural

Implementation

has

of this code,

as a Master's

2.2 General

algorithms.

and Loads Analysis of a Two-Stage Fully Reusable Advanced Launch SysRobinson and D.O. Stanley, Fourth Symposium on Multidisciplinary Analysis

Optimizations,

September

1992,

AIAA

paper

# AIAA-92-4774.

-4-

2.3 Smooth

Surfaces

Recently

there

has been

(CFD)

analysis

to models

which

generate

CFD

an increasing

interest

at the conceptual

grids

and provide

in applying

level.

the

computational

Currently,

corresponding

none

analysis,

fluid dynamics

of the

software

provide

tools

systems for model

generation. As while

a fast

reducing

uniform the

stage the

rational

basic

size

bicublc

building

smoothness

of this,

3.1 Database POST

for

Interface is an event

is batch

oriented

leads

to a high

degree

an ahernate

Current

the

method

be specified.

they

for futme

algorithms to given

exhibit

data

properties

surfaces.

the were

developed

sets.

NURB's

necessary

This work

smoothing

to find were

to carry

resulted

of data sets

out

in a Master's

has

non-

chosen the

as

desired

project

by

extension

driven

program,

the

taking

input

from

POST

data

has

prototype

and

these

to which

an ascii

techniques

favorable. to tabular

The

to the

personnel

variables,

set

above

categories.

flexibility

items.

For

of POST

example,

of input

when

parameters

of such input. prior

work

parameter on this grant

the

the

The

different

for the definition the

into

file.

of data

a completely

implemented

falls

'event'

in the definition

no tools

designed

applies

input

is selected,

provides

extremely

of the

B-Splines",

EASIE

of guidance

which

been

for Data Reduction using Cubic-Rational Department of Computer Science, 1992.

of interdependence

research

a prototype

reaction

approximations

investigated

to POST

POST

into

grant

In essence

of an Algorithm Master's Project,

Enhancements

must

data.

since

needed

on this

Macri.

"Implementation C. Macri, ODU 3.

the

B-spline

blocks

conditions

Ms. Carol

of

personnel

last

piece

of Schwing variables are

Grimm

of POST.

currently

necessary

and

engaged

for a phase

User in one

-5releaseof students,

a new

Ms.

Hima

on integrating data

entry

POST Gurla

data

EASIE

and Mr. Vasu

provides

design

systems

of the

ing the efficiency.

EASIE

that

driven

aspect ascii the

the Athena domain do

and

provides

some

mand

user

time,

and

form

out

carried

work

out by graduate

has also commenced

snipping

the

current

of the data

namelist

integrity

Tsai

and

and

seem

and

analysis

emphasized.

check-

that

in this

area

resulted

in two highly

the application

Ms. Ya-Chen

Kao

to the

public

derived

is rapidly

to

of the

is designed

system

for for

is in the public

becoming

of public

domain

available. software

interface.

master's

environment.

respectively.

tools

in technology

in this system

of the user

modes.

interface

is the windowing

combination

different

improv-

the importance

advances

advances

in two

and

of software

this user

X-terminals

this

Result-

codes.

of the software and

and execut-

codes.

errors

a collection

of recent

of these

analysis

reducing

Currently,

advantage

of X-servers

stand-alone,

released

Most

the task of building

programs

to the next revolution

can operate CCE

and

been

not take

it would

will lead

carried

design

X-Windows.

gazing,

EASIE

by Ms. Chia-Lin

does

simplify

between

On the forefront

in the

hardware

environment,

and

that

a methodology

has

has been

interface.

crystal

both

of EASIE

at MIT,

research since

one

terminals

and hardware

The

being

the application

of diverse,

of data

engineering

of EASIE

project

low-cost

divided

version

utilities

consisting

exchange

the task of coordinating

presenting

the database

will allow

a set of interactive

aided

for simple

At the same

with

This

is currently

EASIE

ing in a streamlining

menu

work

Bokka.

directly

of POST.

and

ing computer

Now

This

described.

3.2 X-Windows

To

interface.

management

requirements

ing previously

ease

user

projects.

These The

The

effort

are the complete work

was

was com-

completed

-6"User Interface Design Computer

Science,

"Application Department

4. Parallel

the

IRIS

They

a certain

amount

efficient

clear

machines

that much

and/or

Master's

for EASIE",

that

Y-C

Project,

Kao,

Department

of

ODU

Master's

Project,

in computing

power

will arise

personnel

of the

Further,

on this grant

standing

algorithm of application

Joe Rehder

of VAB.

have

in to support

machines.

While

adjustment

or distributed Algorithms

near optimally

principal

investigators

programs

will come

this can only been

on

areas

will

that work

occur

extremely

is contained

under of this

direct

this can be seen

VAB

machines advantage

and

can and

do provide

careful

grant

if the proper

the

single

next

utilization ground

in providing

of

processor

new

impact

on research

major

of parallel

work both

of exciting

in the following

environment,

conversion.

that

via the proper

design

investigation

for sequential

automated

in

analysis

of this

requires

developed

productive

a number have

these

to take

initially

Indeed, the

environment

anywhere

development

This

environments.

brought

algorithm

developed.

of analysis

processing.

been

parallel

may not perform

the development

have

improvements

computing

all multi-processor

of any

belief

of the future

distributed

of automatic

being

It is the

number

are

use

the algorithms

tributed

ODU

1992.

computers

programs.

true

Tsai,

Algorithms

use of parallel

new

C-L.

Driven Interface Generation of Computer Science, 1992.

It has become in the

for EASIE",

on

and

dis-

is developed. the basis

architectures being

impact

The

for under-

and

also

conducted

in a

by Mr.

publications.

Optimal Parallel Algorithms for Problems Modeled by a Family of Intervals, ( S. Olariu, J. Schwing and J. Zhang ), IEEE Transactions of Parallel and Distributed Systems, v.3 no. 3, (1992), 364 - 374. A preliminary version was published in Proc. 28-th Annual Allerton

Conf.

On the Power ( S. Olariu,

on Communication, of Two-Dimensional

J. Schwing

and J. Zhang

Control,

and Computing,

Processor ), Parallel

Arrays

Processing

Optimal Parallel Encoding and Decoding Algorithms and J. Zhang ), International Journal of Foundations

1990,

282-291.

with a Reconfigurable Letters,

1, (1992)

for Trees, ( S. Olariu, of Computer Science,

Bus System, 29-34. J. Schwing v. 3 no. 1,

7 (1992), 1 puter

- 10. A preliminary

Science

Conference,

version

of this paper

San Antonio,

Integer Problems on Reconfigurable and J. Zhang ), Journal of Computer

Texas,

J.

Channel Zhang

1991,

in Proc.

1991

ACM

Com-

I - 10.

Meshes, with Applications, and Software Engineering,

A preliminary version has appeared in Proceedings ence on Communications, Control, and Computing, A Constant-time J. Schwing and

appeared

March

( S. Olariu, J. Schwing accepted for publication.

of the 29th Annual 821-830, 1991.

Assignment Algorithm for Reconfigurable ), B/T, v. 32, (1992) 586 - 597.

Allerton

Meshes,

Confer-

( S. Olariu,

Fast Computer Vision Algorithms on Recortfigurable Meshes, ( S Olariu, J. Schwing and J. Zhang ), Image and Vision Computing Journal, v.10 no. 9, (1992) 610 - 616. A preliminary version of this work has appeared in Proceeding of the 6th International Parallel Processing Symposium, Beverly Hills, 1992. Selection

on Meshes

J. Schwing,

with

and J. Zhang

Multiple ), B/T,

Broadcasting,

accepted

( D. Bhagavathi,

P. Looges,

S. Olariu,

for publication.

Simulating Enhanced Meshes with Applications, ( R. Lin, S. Olariu, Zhang ), Parallel Processing Letters, accepted for publication.

J. Schwing,

and

J.

Applications of Reconfigurable Meshes to Constant-time Computations, ( S. Olariu, J. Schwing and J. Zhang ), Parallel Computing, accepted for publication. A preliminary version of this paper appeared as "Constant Time Integer Sorting on an nxn Reconfigurable Mesh" in Proc. of the International Phoenix Conf. on Computers and Communications, Scottsdale, Arizona, 1992, 480-484. A Simple Selection Algorithm Shen, L. Wilson, and J. Zhang lication. Parallel

A preliminary and Distributed

Fast Mid-level Vision J. Zhang ), Parallel EWPC'92, IOS Press,

version Systems,

for Reconfigurable Meshes, ( S. Olariu, J. Schwing, W. ), Parallel Algorithms and Applications, accepted for pubof this work appeared in Proc ISMM Pittsburgh, October 1992, 257 - 261.

Algorithms on Reconfigurable Computing: From Theory 1992, 188-191.

Meshes, to Sound

Sorting in O(1) time on a Reconfigurable Mesh of Size Schwing and J. Zhang ), Parallel Computing: From Theory ings of EWPC'92, Plenary Address, lOS Press, 1992, 16-27.

( S. Olariu, Practice,

Conference

on

J. Schwing Proceedings

and of

nxn, ( R. Lin, S.Olariu, J. to Sound Practice, Proceed-

A Fast Selection Algorithm on Meshes with Multiple Broadcasting, ( D. Bhagavathi, P. Looges, S. Olariu, J. Schwing, and J. Zhang ) Proc. International Conference on Parallel Processing, St. Charles, Illinois, 1992, p. 111-10 - III-17. Fast Component Labeling Zhang ), Computing and and Information, Toronto,

on Reconfigurable Information - Proc. 1992, 121 - 124.

Efficient Image Processing Algorithms Schwing and J. Zhang ), Proc. of Vision May 1992.

Meshes, ( S. Olariu, J. Schwing and J. International Conference on Computing

for Reconfigurable Meshes, Interface, 1992, Vancouver,

( S. British

Computing the Hough Transform on Reconfigurable Meshes, ( S. Olariu, J. Zhang ), Proc. of Vision Interface, 1992, Vancouver, British Columbia, Time-Optimal Sorting and Applications on nxn Enhanced Meshes, ( Schwing and J. Zhang ), Proc. IEEE lnternat. Conf. on Computer Systems Engineering, Comp Euro '92, The Hague, May 1992, 250 - 255.

Olariu, J. Columbia,

J. Schwing May 1992.

and

S. Olariu, J. and Software

-8Interval-RelatedProblems on Zhang

), Proc.

ASAP

Recontigurable

"92, Berkeley,

Efficient Image Computations Zhang ), Proc. of CONPAR

August

Meshes,

( S. Olariu,

1992, 445

on Reeoniigurable '92, Lyon, France,

Zhang

Polygon ), SPIE

Problems Conference

on

Meshes, September

Reeontigurable

on Vision

( S. Olariu, 1992.

Meshes,

Geometry,

Boston,

An Optimal Parallel vertex Cover Algorithm Schwing, W. Shen, and J. Zhang ), Proc ISCIS 1992, 49 - 55. Geometric J. Zhang

Problems ), Proc

ISCIS

on Meshes Conference,

with

Multiple

Antalya,

J. Sehwing

( S. Olariu, Geometry ( S. Olariu,

November

J.

and

J.

Broadcasting, November

J. Schwing Conference,

J. Sch'wing

and St. and

J.

1992.

for Cographs, ( R. Conference, Antalya,

Turkey,

and

- 455.

Convexity Problems on Meshes with Multiple Broadcasting, J. Zhang ), Proc. 4th Annual Canadian Computational John's, August 1992, 365 - 370. Convex

J. Schwing

Lin, S. Olariu, J. Turkey, November

( S. Olariu, 1992,

J. Schwing

41 - 47.

and

-9-

Appendix Master's

Project

Reports

and AIAA

Conference

Procedings

Surface Operations

Generation Applied

and Editing

to Structural

of Aerospace

Vehicle

Susan

Old

Dominion

Advisor:

work was supported

University

Dr.

Professor

under

of

for the degree of Science

James

1992

NASA grant

of

L. Schwing,

of Computer

April,

1This

Department

satisfaction

the requirements Master

Associate

Project to the

Science of

in partial

Project

Fuselages

K. Schwartz

A Master's submitted Computer

Support

NCC1-99.

Science

1

Abstract SMART, sisBranch

Solid Modeling Aerospace Research Tool, isthe Vehicle Analyof NASA

Langley Research Center's computer-aided design tool

used in aerospace vehicle design. Modeling of structuralcomponents SMART

using

includes the representation of the transverse or cross-wiseelements

of a vehicle'sfuselage,ringframes and bulkheads.

Ringframes

are placed

along a vehicle'sfuselage to provide structural support and maintain the shape of the fuselage. Bulkheads

are also used to maintain shape but are

placed at locations where substantialstructuralsupport is required. Given a Bdzier curve representation of a cross-sectionalcut through a vehicle'sfuselageand/or an interiortank, this project produces a frrst-guess Bd'zierpatch representationof a ringframe or bulkhead at the cross-sectional position. The grid produced islaterused in the structuralanalysisof the vehicle.The graphical display of the generated patches allows the user to edit patch control points in realtime. Constraintsconsidered in the patch generation include maintaining %quare-like_ patches and placement of longitudinal, or lengthwise along the fuselage,structuralelements calledlongerons.

Contents 1

Introduction

2

Capabilities

5 of SMART

Aircraft

4

Structural

3.1

Design

3.2

The

of Finite

4.1

Steps

in the Finite

4.2

Creating

6

Algorithms 6.1 6.2

the

9 ......................

Design

Overview

Geometric

7

Design

Considerations

Actual

5

6

9

........................

Element

Analysis

Element

Mesh

11 15

Method

...............

18

........................

18

Representation

21

for Generating

Capabilities New Results

Bulkheads

Developed for SMART ............................

6.2.I

Bulkheads

6.2.2

Ringframes

and Prior

26

PAng&ames

to the Project

....

26 30

.........................

30

........................

36

Conclusion

Appendix the

37 A:

SMART

Implementation

of the

Algorithms:

Snapshots

Display

of 39

Appendix

B: Software

Requirements

Appendix

C: SMART

Code

for

to Implement

SMART Algorithms

Structures

65 103

List

of Figures

1

The Layout of the SMART

2

Ringframe from an offsetcurve [REHDER,

3

Bulkhead between fuselage and internaltank [REHDER,

4

Semimonocoque

5

Typical semi-monocoque

6

Typical transport fuselagecenter sectionfloor ment.

Screen [SMART,

construction [MCKIN,

p. 2-I] ...... p. 3] ........ p. 4]

p. 144] .........

stiffenedsheU--L-1011

8 9 12

[NIU, p. 376]

13

arrange-

beams

[NIU, p. 396] ........................

14

7

Typical pressure fiatbulkhead [NIU, p. 398] ..........

8

Fail-sa/edesign by using longitudinalbeam

9

lage. [NIU,p. 391] ......................... Sketch of main detailsof aeroplane structure [STIN66, p. 205]

10

7

14

along side of fuse15 16

Finitedifferenceand finiteelement discretizations of a turbine blade profile.(a) Typical finitedifferencemodel. (b) Typical finiteelement model. [HUEB,

11

An

arbitrary shape

p. 5] ...............

divided into nodes and elements.

17 The

shape is governed by the partialdifferential equation shown. The

value of this equation at any point in an element is a

function of the values of the nodes _i bounding

the element.

12

[BARAN, p. 3] . ......................... Model reduction due to structure symmetry ..........

19 20

13

Two

22

14

Bdzier curves and their control points [FOLEY,

p. 488] i The Bdzier curve defined by the points Pi is divided at t = into a leftcurve defined by the points Li and a right curve defined by the points P_. [FOLEY,

p. 508] ...........

15

Bicubic Bdzier Patch

16

Vectors and points used to calculatea patch

17

A fuselagecross-section ......................

18

25

.......................

A fuselage cross-sectionwith component

26

..........

29 42

cubic Bdzier curve

segments and control points.................... 19

A simple component

20 21

tank

cross-section

cubic

Bdzier

(simple curve

implies

segments

convex and

segments

and

control

points

2

................

shape)

control

A fuselage cross-section with interior simple tank A multi-bubble tank cross-section with component curve

43 with

points...

44

cross-section. cubic Bdzier

45 46

22 23

A fuselagecross-sectionwith interiormulti-bubble tank crosssection................................

47

A fuselage cross-sectionwith generated interiorcirculartank with cubic B_zier curve segments showing the path of growth for bulkhead patches................

24

. .......

with first-guessbulkhead patches................. 25

48

A fuselage cross-sectionwith generated interiorcirculartank 49

A fuselage cross-sectionwith generated interiorcirculartank with control points (plotted as one-third points) edited to smoother patches..........................

26

bulkhead 27

patches

A fuselage

patches

A fuselage and where

29

original

of near-equal

Initial

bulkhead

A fuselage section

editing

cubic Blue

locations

where

complish

equal

sponding

curves

Initial

of arclength

bulkhead

simple

with

Bdzier squares

on the

original number

given

of near-equal patches

based

between fuselage cross-section section ................................ 33

Bulkhead fuselage

34

after

editing

cross-section

Placement of twelve interior multi-bubble

53 growth

of patches

on cubic and

55 cross-

correspond-

cross-sections were

indicate split and

of arclength Bdzier

54

between ....... tank

between

per cross-section,

percents

curves

cross-section.

multi-bubble

cross-sections

of control and

corresponding

cross-section

green

of curves

to accomplish

points

curves

points.

............ Bdzier

52

locations

tank

interior

.....

cross-section

simple tank

growth

split and

on cubic

of control and

cross-section

and

ing points.

32

percents

cross-section

tank

51

first-guess

curves

indicate

were

cross-section,

and

with

curves.

corresponding

per

cross-section

after

simple

cross-sections

based

growth

growth

between

cross-sections

patches

fuselage

fuselage 31

given

tank

inward

interior

green

inward

interior

curves

of curves

curves

Bulkhead

with

the

B_ier

on linear

growth

on

number

between 30

without

based

Bdzier

squares

equal

on cubic

cross-section

cubic

Blue

based

cross-section

bulkhead 28

50

A fuselage cross-section without interiortank with first-guess

corre-

.......

growth

multi-bubble

to ac56 curves

tank

cross57

points

multi-bubble

of patches tank

between

cross-section.

longerons on fuselage cross-section tank cross-section .............

58 with 59

35

Placement terior

36

Placement interior

37

tank

of thirty simple

A fuselage A fuselage

tank

cross-section percent

on fuselage

cross-section

of thirteen

constant 39

longerons

tank

simple

Placement interior

38

of nine

simple

longerons

on fuselage .................

longerons

with

in. .

cross-section

on fuselage

cross-section along

cross-section

cubic

with constant

61 cross-section

patches B_ier width

60

with with

.................

with ringframe

of growth

cross-section

cross-section

................

62 generated curve ringframe

with

segments. patches.

63 64

1

Introduction

"A model is a representation of some (not necessarilyall)featuresof a concrete or abstract entity. The

purpose of a model or an entity is to allow

people to visualizeand understand the structure or behavior of the entity, and to provide a convenient vehiclefor'experimentation'with and prediction of the effectsof inputs or changes to the model [FOLEY, many

instances,the model is the only means

pp. 286-7]." In

in which analysis can be per-

formed to determine feasibility of an idea. Costs of creatingan actual entity or the testingfacilityfor a particularentitymay be prohibitiveand a model provides the simulation of the entityforexperimentation and learning about a proposed system. The

cost of memory

and computing

the past two decades and made

time has decreased drasticallyin

the computer

one of the most viable tools

for modeling. In particular,graphics-based modeling tools are now used "to createand editthe model, to obtain values foritsparameters, and to visualize itsbehavior and structure [FOLEY,

p. 287]."

In the mid 1970's, the Vehicle Analysis Branch, VAB, ley Research Center, LaRC, system. Numerous

of NASA

began development of itsown

Lang-

solid modeling

commercially produced systems were evaluated and de-

termined not to meet the needs of the VAB.

Thus, SMART,

or Solid Modeling

Aerospace Research Tool, was begun in the 1980's to provide the VAB

with

itsown computer-aided design tool foraerospace vehicledesign. A primary method

of modeling used by aerospace and structural engi-

neers is based on the abilityto create a "nice" grid on a surface. Finite element analysisand computational fluiddynamics both relyon known

val-

ues at points relativelyclose to one another to predict values of quantities likestuctural stressat other points. Currently, the difficulties in producing suitablegrids for these analyses slows the design process. Manual

means of

producing the grids are unsuitable and automating the process is the desired method. The

goal of this project has been to automate the B_zier patch gener-

ation of fuselage bulkheads and ringframes used in the structural analysis of aerospace vehicles. Sections two through fiveof this paper provide insight into the basicsof SMART,

aircraftstructuraldesign, the finiteelement

analysisprocess,and the geometric representationsused in the modeling process. Section six presents the algorithms developed to generate the desired 5

patches. Snapshotsof the SMART display the algorithms are provided as Appendix tures requirements document

showing the implementation of

A.

Copies of the SMART

and source code are prodded

struc-

as Appendices

B

and C, respectively.

2

Capabilities

SMART,

of SMART

written in the C programming

language, was developed for use on

the Silicon Graphics IRIS workstation, a computer graphics

hardware and the UNIX

which features custom

operating system.

The initialmodeling

requirements of the software included: • ability

to generate

complex

vehicle

shapes

easy

manipulation

component

grouping

• facilitate chial • provide

data

analysis

display, small

shown

input

facilitated

to create are

with

extensive represented

components

using

representation

of

a hierar-

to

a variety

of

slider

p.

main

bars

from over

for

"Bdzier

viewing

the

mouse and

primitive

and

shapes cubic

given

curves

evolution.

over

the

pressing

or a series

a

desired

Most menu,

an appropriate that

is, SMART-

or by

"free-hand"

SMART

cross-section 3]."

of the

for displaying

In particular, p.

oc-

or viewports,

shapes,

modifying

[MCMIL,

features

an area

components,

viewport.

"novice,

main

windows and

to the

of vehicle the

The

viewport

basic

creating

arbitrary

2]."

pertinent

in the

to accomodate

menus,

by positioning figure

p. 1].

designed

two large

mouse

by either

was

[MCMIL,

1, are

generation

capability

completely

user

[MCMIL,

be created the

vehicle

geometric

horizontal

and

automatic

rendering an

two

geometric

may

descriptions

easily;

users

is accomplished

Objects

geometric

scheme;

with the

in Figure

bar, or plotted button.

and

of the

of SMART

area,

of menus

quickly

a single

experienced

textport

a variety user

interface

and

3-dimensional

and

interaction

user

casional,

from

programs;

• real-time The

accurate

The

"has

capability cross-sections

of points

connected

® SMART

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Figure 2-1 The Layout of the SMART

E. Mode Menubar

A. Textport B. Clock C. Function

F. View Windows Name Area

D. Information

Figure

Screen

G. View Option Menubars

Display Area

1: The

Layout

of the

H. Menu Display Area

SMART

Screen

[SMART,

p.

2-1]

_t"U

Figure

by straight

2: Ringframe

lines,

discussion Once

of processes.

dation

of the

ment

requirements.

paper,

for the

pp.

3-4]

component

have

of the

the

cross-sections the

currently

and pp.

portion

and

applied

require-

represents

generation provided

and document.

to constructing

the

creating

arate

curve

the

cross-section

representing

The

planar

in several

as in Figure

surface,

different

represented

types

of files.

as in Figure

of a tank

interior

placeB of this

model

curve,

a bulkhead,

fulfill-

[REHDER,

from

a ringframe,

the

longeron

in Appendix

requirements

for a

New

analysis.

offset creating

A

consoli-

is generated between two curves: surface of the fuselage; the other

fuselage

3]."

is the

components. A planar surface curves is formed by the outer the

p.

is accessed

developed,

this project

24-28],

of the

technique

[MCMIL,

component

being

bulkhead

p. 3]

5 of this paper.

for structural

written

See [SOFT,

pertinent

describes

been

[REHDER,

in Section

process

ring'frame

curve

is created,

generation

specifications of many

is presented

A capability,

model

ment

an offset

to as Cartesian

curves

a geometric

variety ments

referred

of Bdzier

from

of these

one of the is a scaled 2, or a sep-

to the

fuselage,

3. by Bdzier In particular,

bicubic

patches,

SMART

has

may the

be stored capability

of writing an ASCII text file of the patch data for an entire vehicle in the format known as a "neutral file." This file may then be "read" by the PATRAN

structural

analysis

program

[PATRAN]

and

this

geometry

is used

as

f Figure

3: Bulkhead

between

to create

a suitable

a template on that

grid

for various

3

Aircraft

3.1

Design

The

design

namics the

of the ture. each

and to the

[STIN66,

payload,

air. fuel,

the various

the

airframe

engines.

perform

[REHDER,

finite

p. 4]

element

analysis

loadings.

is great

design

engineer.

of the This

and

must

the

the

often attitude

190]." 9

run

the

distribution predicting

and

air-loads

a sound these

thousandsw

weight

to the

such as the

of the

engineer throughout

sur-

airframe

loads

within,

is to produce

into

of the

shaped

distribute

structural

aerodyconsiders

reaction

the items

job

the

aerodynarnicist

in accurately

surface,

of both

of specially

must

an accurate

difficulty

of speed,

The analyzes

also protect

engineer's

cases--which

efforts

"envelope

envelope

Given

structure's

combined

shape

structural

combinations p.

stress

the

structural

190]."

The

there

on

critical

then

tank

Design

requires

presence

the

Because point

[STIN66,

the

p.

and

vehicle,

"most

and

as an aerodynamic

surrounding

and

internal

Considerations

air

surfaces

and

Structural

engineer

rounding

grid

pressure

of an aircraft

vehicle

fuselage

strucloads

considers arising

at the

from

the flight

_Structural control,

design

the operational

[STIN66,

p. 192]."

each deserves scope

affects

and

which

at high

• The study in which

of loads the

or bearing, cross-sectional stress. shape defined

and

Shear

are

shear. element.

stress

as the

types

apply

to tensile

it should

ratio,

stiffness.

concern

and

both

the way

it is applied

in a particular

must

way, it is said

tensile,

to the surface.

compressive

caused noted

The

it is stressed.

that

strain

stress.

stress.

stress

material's

Shear

by shear

and compressive

be

in 1-g

is caused by tension across a stress is the reverse of tensile

when

displacement

explanation:

strength-to-weight

of stress:

tangential changes

angular

simplistic approach, strain causes stress.

three

the

on the ground.

the area over which is loaded

Tensile stress Compressive

occurs

multidimensionally definitions

and

and

and smooth

high specific

is of major

a material

There

vehicle

a high

design

are beyond

a cursory

wrinkle-free

and

on a material

When

stressed.

have

temperatures,

load is applied

be considered.

at most,

and

of an aeroplane

for structural

an unloaded

must

stability

full explanations

reasonably

from

envelope, potential

considerations However,

remain

material

flight

development

each win be given

is different

fabrication

to be

the

are many

skin must

particularly

strain

role and

There

paper,

• The outer

• The

achievable

to be fully explored.

of this

flight,

the

causes

is

Similar

Although strain

a and

Heat is also a consideration. The boundary layer of air surrounding a high-speed aircraftbecomes heated and raisesthe temperature of the skin of the aircraft.External radiant heat may also be a factor. The elasticity/plasticity of a material is an important factor. If the strain caused by a stresscompletely disappears when

the stressis re-

moved, the material is said to be wholly elastic.If the strainhas not disappeared, the material issaid to have a permanent

"set" and plas-

ticityhas occurred. "A structure is designed so that the working range of any component

does not exceed itselasticlimit. It is now possi-

ble to study stress-patternsestablished in structural components various states

applied that

proportional

loads ....

within to the

elastic stress

A useful limits

general

law, known

of a material

producing I0

it [STIN66,

the

as Hooke's strain

p. 197]."

produced

by Law, is

• Bending

and torsion or twisting must also be accounted for. Bending

takes place when

a load is applied to a point on the flexuralaxis of

a structural member and the reaction is at another point on the axis. Torsion will also occur ifthe reaction is offsetfrom the flexuralaxis. • Fatigue

is also

studied.

It occurs

lower than maximum structural members. None

tensile

when

stress

repeated

stresses,

allowable,

cause

each

the

much

cracking

of

of these items can be taken in isolationand generally combinations

axe considered simultaneously. "An important aid in structural analysisis the Principleof Superposition: that the totalstraincaused by a load-system may be considered as the sum of the individual strainscaused by the various load components, taken in isolation[STIN66, p. 197]." "The analysis of stress and strain in advanced aircraftstructures has forced the development of very elegant and complicated mathematical niques. The dynamic

structural engineer must

tech-

relate the effectsof weights, aero-

inputs, elasticresponses and stress distributionsthroughout

the

structure as one whole, for a wide variety of differentshapes. Fortunately, the grid-likeconstruction allows accurate analyses to be made into mathematical

and translated

statements that can be handled by computers

[STIN66,

p. 213]."

3.2

The

The

airplane

This

paper

Actual has

Design three

will only

basic

address

parts, the

the

fuselage,

the

parts

of which

fuselage,

wings, are

and

the

the

focus

tail. for

this project. "The airplane cargo,

controls,

capacity a spacecraft

seen

is the

axe attached

airplane.

the

fuselage

and

and

and

It should

body

other have

which items,

the

aerodynamic or missile

to which

wings

provides

space

depending

upon

smallest qualities

may

the

streamline of the

be called

but

4 and

5 .

This

means

11

that

the

tail

crew,

the

and

size

consistent

... The is more

body or tank [MCKIN, p. 140]." The modern aircraft's fuselage is of a semi-monocoque in Figures

the

for the form

airplane

a fuselage

and

fuselage

main

unit

of an

passengers, design with

of the desired

structure

commonly

called

construction, has

of

a framework

as

Figure 4: Semimonocoqueconstruction which

supports

placed

on the fuselage.

elements. called

The

lage's

frames,

longitudinal

little

doors

in Figure

plates

serves

of the

at the frames

than

that

This

of the

but

are

paper The

helps

6.

to distribute may

are used

of the

to maintain

types

support

over

areas

to the fuseat

the skin

for doorways

the structural

are

is a substantially

is placed

the loads

stresses

of structural

perpendicular

A bulkhead

be cut-out

of the

fuselage

A bulkhead

a fuselage,

144]

most

of several

or rings•

across

as in Figure

primarily

cross-section

loads frame

consists elements

formers

There

withstand

p.

points

of

and

allows

and

holes,

requirement,

as seen

7.

A frame outline

and

and

expansion. and

must

framework

cutting

beam,

loads,

radial

which

or transverse

cross-section

concentrated

skin

The

vertical

bulkheads,

constructed

but

an external

[MCKIN,

are

ported

by the

bulging

due

smaller and

and

are used

components

bulkheads

to severe

and stresses.

shape

which

or rings

of the

body

can be seen

construction

Formers

to all of these

longitudinal

the

of the vehicle,

bulkheads.

lighter

refers

to maintain

and

in Figure

of the frames have

to maintain

the same

a uniform

has

can

8. The

be lighter

outline

shape

the

as the

of the

skin.

as ringframes. are longerons

frames They

and also 12

and

support are

used

stringers. the

They

are sup-

outer

skin

to prevent

to carry

the

axial

loads

Figure 5: Typical semi-monocoquestiffened shell--L-1011 [NIU, p.

13

376]

lhaN

r-tm_

Figure

6: Typical

transport

fuselage

center

section

floor

beams

arrangement.

[NIU, p. 396]

!!

Figure

7: Typical

pressure

flat

14

bulkhead

[NIU,

p. 398]

Longitudinil_

Ii.

_','_"

_

. =,=,,

__

8: Fail-safe

[NIU,p.

\

"_C'_'C/

Poor _lm

by using

longitudinal

beam

along

by bending.

and

Longerons

aft of the

vehicle

are

and

especially

run

the

designed

length

to take

of the

and of lighter construction. See Figure 5. external skin is formed from metal sheets which

frames

and

stress and above. The

bulkheads cabin

a high

4

pressure.

and

to weight locations.

total

failure

Overview

Finite 1]'.

Figure

element

Originally

9 shows

ratio,

and

It has

design

through

load

is defined

the

it is well

suited and

redistribution

to be a "group

equations

developed

for the

of any study

15

loads

Stringers

are to the

loads

features

to be "very

Element

governing

the

combined

flexibility

end

are attached

It carries

is considered

of Finite

analysis the

or welding.

structure

strength

without

approximating p.

by riveting

semi-monocoque

combinations failure

of fuselage.

the

fuselage.

shorter The

has

side

391]

caused fore

design

I I _-.;7

_r I.

Figure

._./3.

of sheer

mentioned

efficient,

i.e., it

for unusual

can withstand [NIU,

load local

p. 377]."

Analysis of numerical

continuous

of stresses

methods

system in complex

for

[BARAN, airframe

'Ruddavain_- combinedelevsLof Tailplmes famed dthol ss bqr| D-oosedtelsina I_uts I by sepillte Iti_ and spas

_lefms andflapssimi_ to

__

Crasharchattached to lawwd bulkheadand box bwa keel Suplxxtsporta_,.tst=bo_d |lazed petal-lype canopydoocs

"

Lar|e box-beamkeel fastenedto main luselafe hzme,suppeflsseals, ho_ses

spazs,born _d IroeLfuselage box-bern. Rent framesupportsenginemounting

rellact_blenosewheelat forw_d end. controlr_s androds andtakes

Figure

9: Sketch

andluddeg:telJJs8 edle sj with r|bletsmd skimordishedskin to replace s41blllslq r&inls.

of main

"

Separateribs andsparset torsionbox with I_nose leadingedgelairin|.

__

details

of aeroplane

16

structure



(STIN66,

p. 205}

Figure 10: Finite differenceand finite element discretizations of a turbine blade profile. (a) Typical finite differencemodel. (b) Typical finite element model. [HUEB, p. 5] structures [HUEB, p. variety

of engineering

complex

costs

and scientists. of this method. The values

The

model. and

This

process

of creating

to the

tire problem. determine

in Figure

elements The the

then

size and

accuaracy

at selected model

connected, and

the

original

nodes

of the

combined

of the

elements assumptions model.

to represent

of elements

analysis.

17

and

a suf-

system

is

of the

discretization made are

a solution simplifying

struc-

governing

elements

equations,

Solutions

many

with

physical

are

users

of the

is called

differential

engineers

the

the

and

infinitely

points

of the define

to

frequent

point

is to approximate

nodes

number

is the

analysis

when

all

most

at each

with

restricted

to virtually the

in a

in hardware

or structure

10. Simplifying from

specified and

evaluated

was

declines

remain

used

for problems

analysis

or structure

A mathematical

or nodes,

functions,

applied

individual

element

points

is illustrated

being

system

of accuracy.

The

available

engineers

is also

effective

process

system

today

element significant

this

quantity of the

finite

but the

aerospace

of finite

equation

approximating then

unknown

degree

created.

made and

method

It is particularly

of a continuous

objective

differential ficient

have

element

recently,

computers,

Civil

difficulty of the

ture.

Until

mainframe

processing

finite

disciplines.

geometries.

expensive

3], the

to create which

are

created

for

for the

en-

assumptions

4.1

Steps

in

Finite

element

which

has

the

Finite

analysis

its own

Element

Method

Can be performed

difficulties

and

time

in a sequence

of five steps,

requirements.

They

are

each

of

summarized

as follows: .

Perform ments

the

discretization.

is the most

accuracy

of the analysis.

on the nature next section. 2. Define erties .

Dividing

important

boundary

elethe

take various

This is discussed

conditions

in nature

analytical

into affect

or loading

polynomial

The

may

structure

this will greatly

of each element

interpolation

them.

the physical because

properties

Formulate tiating

Elements

of the problem.

the geometric and

phase

equations because

of the

expression

in greater

and

ease

in the

any material

prop-

to the

element. in these

for the displacement

at any

analysis.

These

in integrating

functions

depending detail

pertinent

for each

interpolation

shapes

are

and

differen-

equations point

often

give

inside

"an

the ele-

ment" [BARAN, p. 4]. The value of the equation at any point in an element is a function of the nodes bounding the element. See Figure 11.

.

Assemble Step

.

the system

2 above,

Make additional equations

may

and

equations,

solve

calculations, be used

accounting

if necessary.

to calculate

structural analysis, nodal values values are then used to calculate

4.2

Creating

the

There

are two basic

spring

elements

variety

of engineering than

plate than

the

outlined

in

other

The solution

of the system

of

parameters.

For example,

in

represent body displacements. These strains and stresses in the elements.

Mesh

categories

are examples

greater

for properties

the equations.

problems

cross-sectional

or shell elements. The their other dimensions

of planar

elements:

of line elements. to represent depth

line and

Beam parts

or width.

area.

elements whose

Area

are

lengths

elements

plate elements have a thickness and are usually represented by

18

Beam used are

in a much

include much three

and

flat

smaller or four

Y7 a2_

_z_

.I

j Figure

11:

An arbitrary

is governed

by the

equation

at any

point

nodes.

or volume

The being

model

structure placing

being likely

this

that

it is a "waste

that

of the

by the

the

location

shape

of time

and

element

of the

corners

and

of the

accounting

actual

pattern

the

Other

of nodes

p.

The

size

on and

19

structure

regions

mesh

meshes John

having

of the

is created,

can be created

M.Biggs

precision

element

model

locations

model

symmetry,

the

as saying

greater

than

88]."

significant The

structure.

choice

Finer

to account

physical

A coarse

quotes

of the finite

a coordinate system with an origin definition of nodes and elements. Ultimately,

nodes

dimensions.

problem,

methods

[HUEB,

structure's

shape of this

of the

used

of the actual

physical

Huebner

discontinuities.

for the

value

values

of element

are determined.

to employ

nodes.

The

The

to other

and load points.

analysis

elements.

of the

compared

the

if necessary.

of the

and shown.

type

is an idealization

support,

mesh,

input

shape

structure by

initial

The

are a third

to be stressed

at stress,

from

equation

is significant

created

nodes

p. 3]

By understanding

most nodes

elements

x

is a function

[BARAN,

thickness

analyzed.

into

differential

element.

whose

divided

in an element

the

Solid

shape

partial

• ; bounding

for parts

/

should

of the

of nodes closely

model

can

as in Figure

an axis elements

is determined

12.

of symmetry depends

be

reduced

Establishing allows

on

include

approximate

the

easier type

of

I

I

I I



I _axm

Figure 12: Model

finite

element

suggests

analysis

being

the following If the

using

analysis

• Nodes

should

where

to transition should

from

be made

When

using

plate

ferred

shape

because

elements

should

stresses

and

or discontinuity

points,

as displacements should

a series

they

in the

99]. _ analysis.

other

locations is required.

If it is necessary

dimensions

a factor

elements,

are more only

the

only

p.

of two.

of adjacent The

transition

of elements.

or axisymmetric be used

than

should

"localized

displacement

if possible.

to fine meshes,

disconti-

strains

and

94-99]:

mesh

or temperatures,

be used,

by more

pp.

that

[HUEB,

load

differ

across

states

at supports,

coarse

not

This

Huebner

geometric a refined

than

spacing

should

principle. cause

[HUEB,

and/or

requiring

mesh

such

required.

modeling

a more refined

be placed

mesh

elements

Venant's

accuracy

loads

and areas

of the load

information,

Uniform

concentrated

St.

requires

the

element

discontinuities

vicinity

• Stress

and

for finite

dimensions

or geometric

immediate

performed

involves

minimum

be determined loads

reduction due to structuresymmetry

as rules

problem

nuities,

of symnmtryJ

when

transitions.

2O

accurate required

quadrilaterals than

triangles.

by the

are

the pre-

Triangular

geometry

or for



The

aspect,

ements

or length-to-width,

should

be as close

as 5.0 are permissible, • In triangular angles

and

should

all angles ations

but below

quadrilateral

be used.

are

60 degrees,

surfaces

all in one should

should

plane.

be less than

• Poisson's in the

ratio,

material

optimum

or right

el-

as large

obtuse

angles

in the

or acute

triangle,

quadrilateral,

where

but

devi-

with flat elements by the

whose

surface

nodes

and

the

are

plane

15 degrees. be less than

of an applied

contracts

no extreme!y

is the equilateral

subtended

An

elastic

while

direction.

in the tension

Poisson's

0.5.

tension

to the tension

to the tension.

ratios

is permissible.

angle

should

direction

perpendicular

or quadrilateral Aspect

3.0 is preferrable.

be modeled

The

of triangular

as possible.

elements,

The

of up to 30 degrees

• Curved

ratio

to unity

elongates

its cross-section

During

direction

material

and

simple

contracts

compression,

expands

the

perpendicularly

ratio is the ratio of the resultant

perpendicular

strains to the parallel strains. Most metallic materials have a value of 0.25-0.3 and an assumed value of 0.3 is used. It is also assumed that Poisson's material

ratio approaches [NILES,

• Lengths

and

of zero

may

areas

nodes

It is assumed ness.

5 Vehicles shape

the

of the

smaller

elements

for the

twisting

model's

fiat

must

be non-zero.

Values

results.

elements

fiat plate

Geometric are drawn

area

not extend across to cause numerical

that

If in-plane

represent

and

unpredictable

and

reach a maximum

151-152].

of line

produce

Elements should ness. This tends ditional

pp.

0.5 as the stresses

discontinuities or changes in thickerrors and inaccurate results. Adshould

elements

is allowed,

have plate

be used. no in-plane elements

rotational do not

stiff-

accurately

plates.

Representation using

vehicle•

curves There

and are

surfaces

numerous

21

which ways

approximate

the

desired

to represent

such

curves

D

It /

/



/



'_.

r

p,

Figure 13: Two

Bdzier curves and their control points [FOLEY,

p. 488]

and surfaces. As surface representations are a generMization of curve representation, this section will firstconsider working with curves. Often, a parameterization of curves,where each coordinate, z, _/,and z, isa function of a parameter, t, i.e.,z -- z(t),I/= _l(t),z= z(t), is used to avoid problems occuring with explicitand implicitequations used to describegeometric figures.For specifics, see [FOLEY,

p. 478].

The predominant method used in SMART

isthe B_zier form of the para-

metric cubic polynomial curve segment. This consistsof 4 points, Po, /'I, P2, and P3 where P0 and P3 are endpoints of the curve segment and PI and P2 are additional controlpoints. Generally not on the curve segment, points JD1

and P_ indirectlyspecify the tangent vectors to the curve at P0 and P3.

Specifically, the directionof the tangent vector at Po is determined by PoP2 and the directionof the tangent vector at P3 is determined by P3P2.

See

Figure 13. To determine a point P on the curve segment, the parameterization of the domain The

is set up so that

weighting

factors

at parameter

for each

t -- 0, P -

point,

known

are:

Boa(t) B,_(t) B_(t) B_(t)

= = = =

22

Po, and

as the

(i - t)_ 3t(1 - t)_ 3t_(1-t) t3

at t = 1, P = P3.

Bernstein

polynomials,

The resultant equation to evaluate P is:

e(t) = Z Pj× B](t) j----O

Note

that

of cubic 2-D;

P(t)

is guaranteed

polynomials.

z, !/, and There

to be cubic

The

sum

in t because

is computed

it is a linear

for each

combination

coordinate,

z and

y in

z in 3-D).

are

several

advantages

inherent

to this

Cubic curves do not "wiggle" as much

representation:

as higher order polynomials and

give a relativelysmooth approximation of the desired shape. Note that a cubic curve is the lowest degree polynomial to interpolate to four requirements: the two endpoints and the specifiedderivativesat each endpoint [FOLEY]. • The

resultant curve segment

is contained by the convex hull of its

representativepoints. This guarantees that the curve segment isplanar. Calculation

of the

notably the

at the

linear

The

endpoints,

combination

storage

points

derivative

is easy. of the

requirements

and

possibly,

at any

point

For a given

derivatives

for a curve

information

on the

curve

t, P'(t)

of the

are

slope

continuity

most

is calculated

Bernstein

segment

about

segment,

as

polynomials.

minimal--the with

four adjoining

segments. Another

way

of pairs

of the

resentation

to compute given

four

to inherit

the

P(t)

involves

points.

formation

is applied

generation,

or if the curve

transformation. be applied computation

to the

four

linear allows

four

these

23

from

viewing

points

time.

points,

interpolations the

invariance.

scaling, rotation, result is the same

is generated

control

linearity

of a_ne

original

Therefore, to the

This

property

applying an affine transformation, lation, to a Bdzier curve, the

successive

Bdzier

That

shearing, whether

followed

the points,

of the segment,

or transthe trans-

by the followed

transformations which

rep-

is, when

need

curve by the only

minimizes

To represent end.

a given

Continuity

shape,

of segments

successive

is guaranteed

the next curve. If slope continuity then P_ and P3 of the first curve remain

coUinear.

Sometimes eter

Moving

a B_zier

t is normally

place would

curve should

be split.

be exactly

the original

[FAR.IN,

is the piece

pp.

technique

75-77]

on the curve

and

HRs.

and

gives

The the

point point

L4 (which Q(t)

t. The

Ra, R2, Rs,

four

center

four

s:

where are

ratio the

and

x

of distances

curve,

or the

of the curve [0, c] and the

pp. 507-510]

the geometric by drawing

and

construction

As in Figure

slopes

the

L3R2

value

a point

X

of the

patch.

collinearity points points

second

14, "the

point

the construction

form

P(s,

must

same

Bdzier

points

ratio

curve

at

for the first

Bdzier

bicubic

patches

in a 4 x 4 gridlike

a Bdzier

curve

pattern.

segment.

The parameterization

t) is calculated

The requires

by:

Poo Pol ?o2 ?o.s Po6 Po8 Po9 P1o P. P. Pl4 for the Bernstein Slope

points

on either

be consistent

24

t2 t 1

between

point

side of the

_3

polynomials

continuity

of a control

on either

control

by the

of the

tttt3 L2H

curve.

positioned

patch

of the surface.

matrix

between

control

divides

to surfaces.

points,

of the

MB

by maintaining

boundary

control

coefficient

control

RI)

p. 508],"

R.t are for the

t, and

points

the

using

of t is found

can be extended

control

1 ]

is the

the

interval

La, L2, La, and L4 are the control

and

a side

s and

control

achieved them

s

MB

the

on

points

two variables,

sz

points

by sixteen

points

If the param-

the first piece

in 1959.

is also

[FOLEY,

representation

are determined

value

endpoint(s).

of t in this interval

c along

to [c, 1]. [FOLEY,

this process

is required, curve must

it divides P1P2 and P2P3 in the ratio of t : (1 - t), divides P2Pa and PaP4 and L3R_ to likewise divide

curve

B_zier

a value

In essence,

by F. de Casteljau

parameter and

[0,1],

end-to-

is set to P0 of

at the

curve over the parameter's

for a parameter

line L2H so that so that it similarly

the slope

percentage

corresponding

describe

developed

if P3 of one curve

over the interval

the

curve

are placed

to be split into two pieces.

a certain

second

The

curve needs

to represent

where

curves

from one segment to the next and Po and P1 of the second

P2 or P1 "controls"

defined

can be specified

B_zier

is

between

Additionally,

side of the the

the P;'s

two patches

on the border

border.

along

and

boundary

edge.

the and

Calculation

L2_'

L3

= [I 4

4

at t = x into by the points

Figure 14: The B_zier curve defined by the points P/is divided a left curve defined by the points Li and a right curve defined /_.

[FOLEY,

of the with

p. 508]

slope

at a given

respect

point

to parameters

All surfaces

in SMART

sometimes

two other

ever,

is equivalent

to the

representation the

B_zier

endpoints

curve

curve in this

curves

for clarity

The tangent utilizes There

in editing

multiple,

representation

vectors

to each

matrices which

which are

is the

endpoint and the allow

included

is the

one-third

of t = 0,½,§,

and

are the spaced

B_zier

method.

Often

vectors

conversion

in Appendix

25

The from

The

on

that

the

one-third

directly

on the

curves. the

Hermite

slopes

of the

representation

to represent one

point

points

Note

same.

other

two tangent

1.

how-

of which

of the

points

closely known.

patches; each

first

"control-like"

are easy

bicubic

values

to place

derivatives

are used,

coordinate

representations

project

B_zier

The

the

values

for both

the two endpoints

the other,

with

using

by partial

15.

for curves

representation.

Hermite

are

t. See Figure

are represented

at parameter

used

are

is achieved

representations

requires

of the

points

s and/or

B_zier

which

on a patch

the curve.

representation

C in the matrices2.h

file.

to

14

11

75

12

3

o

Figure

6

Algorithms

15: Bicubic

for

B_zier

Patch

Generating

Bulkheads

and

Ringframes 6.1 As

Capabilities Project with

many

redrawn

graphics

at speeds

has remained

Developed programs,

which

routine

and

based

on its present

coordinates,

the

mouse

over a menu,

a bar,

while

of the

The

This main

loop

performed.

The

time

(true)

exit else

main

if over

a main-menu

option

loop and

redisplay;

a menu

checks

then

begin 26

then

is constantly

the

mouse

the

user

the

by explicit

of SMART

the

accomplished

is:

image with

location

had

Based

or editing

through

to the

that

on the screen.

loop is exited

loop in this portion

begin if choosing

screen

whether

are accomplished each

Prior

believing

is generally

or over a viewport

is refreshed

main

on the

eye into

determines

calculations

display

being

structure

software.

certain

The

of the function The

in the

position,

are available.

image

human

on the screen.

a looping

mouse's

the

fool the

continuously

for SMART

placed on the

capabilities

loop, menu

regardless choices.

if

over

main-cross-section-menu

exit

main

loop and

then

redisplay;

else if over store-patches-menu store else

patches

if over

in SMART

data

type.of.growth.menu

redisplay else

then

patches

if over

using

structure

B_zier

or linear

growth-direction-menu

redisplay

with patches

and

redisplay;"

then i_orrnat;

then

interior

or exterior

to cross-

section; else

if over store

new-edge-menu

partial

then

patches,

leading

edge,

begin

and

new calculations

from

old

redisplay;

end else

if over

a bar

then

begin if over

patch-growing-bar

calculate

partial

then

patches

redisplay; if over radius-bar

else

calculate else

new

given

redisplay; if over centerline-bar

then

and

percentage

and

then

patches

calculate else

to given

new patches

given

new

radius

length

new

centerpoint

and

position

redisplay;

if over

ringframe-bar

calculate

new

with

then

patches

ringframe

for ring'frame

value

and

redisplay

patches;

end

else

if over edit

the

control

right-view'port points

and

then redisplay;

end The fuselage symmetry

initial

algorithms

cross-section of the

for creating

represented

cross-section

bulkhead

by a linked about

a vertical

27

patches

list of Bdzier axis

centered

on a given

curves.

Due

to the

of symmetry,

the

cross-

section

representation

is actually

Figure

12. For the remainder

imply the "half-cross-section" Because many interior spherical

in shape,

of a tank, on the tank

axis

to the

created

fuselage of the

of the

a first-guess

cross-section,

with

cross-section.

around

the semicircle

one-third

The centerpoint

semicircular

points

of the

of the semicircle

on the fuselage cross-section. external to the cross-section by aerodynamicists The patches

will

cross-section

endpoints The

between

on the

points

on the

to correspond

to the

curves

of the at the

fuselage

calculated

and the default to any one-thlrd

The analogous representation has also been developed and may

for computational

generated

its

was placed

midpoint between fuselage cross-section endpoints, was half the minimum distance from the centerpoint

used

as in

to a cross-section

fuselage

were generated

of arclength

cross-section.

reference

cross-section,

unless explicit indication to the contrary. tanks of a vehicle are spherical or multi-bubble

of symmetry

cross-section

percent

of this paper,

the software

interior

one half of the complete

radius point

using a circle potentially be

fluid dynamics.

the given

cross-section

and

the semi-circle

represented a structural bulkhead between the fuselageand the tank. The percent-of-arclengthguide for generating tank points enabled the patches to have reasonable wedge-like shape, which is as close to square-likepatches as possible. The originalalgorithm was as follows: procedure begin for

bulkhead-first-guess

each curve

(cross-section,

in cross-section

centerpt,

radius)

do

begin calculate

1/3

calculate

inward

calculate

normalized

of each

pts on curve;

1/3

pointing

normal

vectors

from

vectors centerpt

1/3

pt;

in direction

point;

calculate tank-points at length radius direction of normalized vectors; comment:

to each

The

from

centerpt

in

two points and two vectors comprise

the Hermite representationof the curve, as seen in Figure 16.

28

C_laterpomt

Figure

I6:

Vectors

calculate 1/3

B_ier

and

B_zier

patch

points

curves

points

calculate place

and

used

to calculate

between

a patch

corresponding

tank-points;

patch

on linked

from

4 B6zier

curves

list;

end end Using ated

established

to enable

radius

the

of the

at most decrease

only

to move

is tangent

to the

or B6zier

Editing Because

fuselage

points

a position

patch points

on the

the

axis growth

Menus

is important

to allow

were generated

29

the

tank

fuselage until are

menus

is used

radius

bar allows

between

and

the

The

of symmetry

cross-section.

tank

until

in the

Another

bars A bar

growth

cross-section.

a bulkhead.

along

curve

of control the

fuselage

graphical

parameters.

allowing

to represent

and

semi-circle linear

routines,

to change tank,

to the

to zero tank

user

interior

tangent

interior

SMART

the the used

were

cre-

to change

the

cross-section is also

where

allowed there

centerpoint tank

is to

is no of the

cross-section

to allow

choice

of

cross-sections. smoothing according

of patch

wedges.

to a given

radius,

these

points

termining circle.

can be _dragged" the

change

Movement

and one-third Patch

is restricted

points

corner

with

the mouse

in arclength

to tank-points

on either

points

around

and recalculating

side

of the

which corner

on the axis of symmetry

the

the

semicircle

actual

are patch

point

are

on the

"corner"

are then

required

by de-

point

points

recalculated.

to remain

on the

axis.

The

eight

"dragged"

patch

with

control

points

the mouse

not

to smooth

on either

the

cross-section

interior

shape

may

also

of the patches.

be The

change in mouse position is used to calculate the new one-third point position. Points on the fuselage may not be edited in order to preserve the previously Due

determined

to the

speed

redisplayed

6.2

shape

based

of the

Silicon

on aerodynamic Graphics

and

structural

processor,

constraints.

changes

in patches

are

in real time.

New

Results

The specifictasking of this project was to allow automatic generation of a bulkhead or rin_ra.me for a given cross-section(s).The bulkhead would be drawn between

two given cross-sections,one representing the fuselage and

the other representing the interiortank.

This allows the interiortank to

have any predetermined shape and not be limited to being circular. The ring[tame would be drawn interiorto the fuselagecross-sectionat a default width which could be edited.

6.2.1

Bulkheads

There

were

head

between

patches

several the

problems

two cross-sections.

supports

the

current

sponding curve points that both cross-sections ments. may lems

Even not

if the

pair

were

of successive when

differences

Locations

number with

curves where

The

method

in creating

patches

requirement

of calculating

for

to have each

the

on each

in arclength splits

are

of curves to create following

is the

was

"nicely"

shaped which

greater are

their

algorithm

cross-section, made

same,

patch

using

splitting than

internally

3O

These

into

a predetermined stored

and

corre-

arclengths

compared curves

bulk-

problem is curve seg-

respective patches.

the

"square-like"

of the two cross-sections. The most obvious may not have the same number of B_zier

up in a fashion

solved

to consider

prob-

arclengths two

curves

percentage. create

an

addi-

tionalediting capability,explained in further detailbelow. The algorithm is as follows: procedure

match-curve-arclengths (faselage-cross-section, tank-cross-sectio

n)

begin calculatepercent of arclength of each curve in fuselage-cross-section; calculate

percent

of axclength

of each

curve

in

tank-cross-section; determine are look

value close

curves

there

and

curve

percents

of arclength

enough;

at first

while

where

in each

is another

another

curve

cross-section;

curve

in the fuselage-cross-section

in the

tank-cross-section

do

begin if difference curves

in percents

close-enough-value begin split

curve first

look

of arclength

in each cross-section

than

then

with larger

curve

of current

is greater

percent

will have

at second

curve

same

of split

of arclength

(pal):

pal as smaller curve

(other

curve; piece

of larger curve, farther along the cross-section) and the next curve on the other cross-section; end else look at the

next

curves

on both

cross-sections;

end end This the

same

algorithm number

accomplishes of Bdzier

percents of arclength, information is stored

curves

two things: and

both

corresponding

cross-sections curves

end have

up with

near-equal

within an agreed-upon factor. As mentioned above, as to which curve endpoints were created by splitting 31

originalcurves. Although

the percent of arclength is a reasonable way to

lineup corresponding curves, it is sometimes preferrableto move

the curve

endpoints to straightenthe patch wedges. "New n endpoints can be "dragged" with the mouse:

the change in mouse position is translated into the change

in percent of arclength of the split in the originalcurve and the original curve is resplitwith the new percent. The subdivision of a Bd'ziercurve is accomplished by finding control points of the curve as represented by a higher degree polynomial.

Each piece of the curve willrepresent the same

cubic polynomial on itsown intervaldomain, as explained in Section 5 of this paper on Bdzier curves or [FARIN,

pp.

75-6]. Therefore, each new

curve is an exact duplicate of the corresponding piece of the originalcurve. By returning to the originalcurve each time, the originalshape of the crosssection is preserved, but editing of at least some of the curve endpoints is now also a feature of the software. The other problem that needed consideration was the placement of Iongerons in the longitudinalstructuraldesign. The places where these longerons intersectthe fuselage cross-sectionneeded to be at "coruer" points of the patches for laterstructural analysis,as explained in sections3 and 4 of this paper on aerospace vehiclestructure and finiteelement analysis. The shape of the vehiclein many

instancesreflectsonly aerodynamic requirements, and

curve endpoints in the fuselagecross-sectionare usually not in the locations of longeron placement. The guidance from engineers at NASA cleAnalysis Branch can be summarized:

Langley Research Center's Vehilongerons are ideallyspaced equally

around the fuselage,but must especiallybe placed at discontinuity points, or curve endpoints where successive curves are not slope continuous with one another. Thus, a percentage of the longerons to be placed on the crosssection,equal to the percent of arclength of the portion of the cross-section between discontinuitypoints, should be equally spaced between the discontinuity points. If the desired placement of the longeron is too close to an already might

existing be created.

curve-length, percent between The

curve

endpoint,

To resolve

from

the

of the equal

curve

spacing

discontinuities, resulting

tion of a comparison

value

this,

narrow

if a desired

endpoint,

could

is shown

in two

to determine So_

which

longeron

for that

longeron

used

patch,

corresponding

curve-length

the

algorithm

a very

is undesirable,

position

is within

to less than section

be placed

of the

twenty-five cross-section

at the endpoint.

parts.

The

if the

placement

first

is the of the

computalongeron

a

requires curve

the splitting

of an existing

curve or if it will be placed

on an existing

endpoint: procedure

compute-compare-value

push-up-length, comment: and

back-up-length,

Because not

longerons

exactly

at the

push-up-length, positioning back-up-length, and

length-not-yet-included) may

located

past

located

previous

yet,

keep

position the

curves

track of the

term

of differences

in the

curve

of the

in section

compare-value

curve-length total

fuselage

total

to equal-spacing-length

calculated

longeron.

in the following

of the

end of equal-spacing-length,

or the

previously-placed

quantities

of the

difference the

did not

"section"

endpoints

end of equal-spacing-length,

which

the current portion discontinuities.

begin if first

the

before

the

difference

or the curve-length point

at curve

equal-spacing-length,

length-not-yet-included,

from

be placed

or the curve-length point

positioning

(equal-spacing-length,

and The

algorithms

axtual

use of refers

cross-section

to

between

then

= equal-spacing-length;

else begin if push-up-length

and

compare-value else else

if longeron

on previous

algorithm

= compare-value

for placing

push-up-length;

longerons 33

+ back-up-length;

curve -

end actual

then

> 0 then

end

The

-

= equal-spacing-length

not placed

compare-value

zero

> 0 then = equal-spacing-length

if back-up-length compare-value

are both

= equal-spacing-length;

if push-up-length compare-value

back-up-length

is:

then

length-not-yet-placed;

procedure

place-longerons(f_selage-cross-section, number-longerons-to.place)

comment:

The first

endpoint

of the

cross-section,

beginning further

along

the

of a curve

is the one

the second

closest

endpoint

to the

is

cross-section.

begin for each

section

of fuselage-cross-section

between

discontinuities

begin number.longerons-for-section

=

( number-longerons-to-place) if number-longerons-for-section

x (pal-of-section);

> 0 then

begin calculate

equal-spacing-length;

comment:

equal-spacing-length

= pal-of-section

by (number-longerons-for-section look

at first

while

divided

+ 1)

curve of section;

all longerons

not placed

in section

do

begin compute-compare-value; if pal-current-curve

= compare-value

then

begin place look

longeron at next

at second curve

endpoint

of curve;

in section;

end

else

if pal-current-curve

begin if not first longeron

curve was

34

> compare-value of section not placed

then

and on previous

curve

and

do

compare-value

< 25% of equal-spacing-length

begin place

]ongeron

back-up-length

at first endpoint

of curve;

= compare-value;

end else

if pal-current-curve differ

and

compare-value

by > 25% of equal-spacing-length

then

begin split

current

place look

curve

(wrt

longeron

at split

at curve

beginning

compare-value); point; at split

point;

end

else

if pal-current-curve differ

and

compare-value

by < 25% of equal-spacing-length

then

begin place

longeron

at second

push-ahead-length pal-current-curve •look at next

endpoint

= difference

curve

and

of curve;

of

compare-value;

in section;

end end

else

(pal-current-current

< compare-value)

begin increase

length-not-_let-included

by pal-current-curve;

look

at next

curve

in section;

end end place

longeron

at last

end end end

35

endpoint

of section;

then

This algorithm would be applied to the fuselage cross-sectionprior to the match-curve-azclengths algorithm to ensure that the interiortank crosssection matches the fuselagecross-sectionfor which the longerons have been considered.

6.2.2

Ringframes

The originalalgorithms enabled constant percentage ringfxames, i.e.,those ringfraxneswhose width at each one-third point of the fuselage cross-section •was a given percentage of the length of the Bdgier curve from the one-third point to the corresponding tank cross-sectionpoint,to be created. However, in actual aerospace vehicledesign, the requirement forringframes isconstant width and not constant percentage, although constant width is a misnomer. At points of discontinuity, the width of the ringframe isusually a littlewider, the leading edge of the ringframe maintaining the basic shape of the crosssection at a place of greater structuralstress. To create a realistic width for the ringframe at points of discontinuity,the followingalgorithm was used to change the calculated "normal" to the crosssection at 1:hediscontinuitypoint. When normal vectors to each one-third point are calculated,because the tangent to each curve at the discontinuity is different,the curves would have a differentnormal vector emanating

from

the same point. This algorithm provides an alternativeto just averaging the two norrnals at the discontinuitypoint: procedure

normal-at-discontinuity

begin for

each

discontinuity

point

do

begin calculate first calculate

normal

vector

to second

endpoint

curve meeting at discontinuity; normal vector to first endpoint

second compute normal

curve points

meeting

of of

at discontinuity;

corresponding

to tails

of two

vectors;

compute

tangent

compute

intersection

vectors

to each

point

36

curve

between

at discontinuity;

two lines

through

respectivepoints at vectors

the head

in the direction

new-normal

of the normal

of the tangent

-- vector

from

are then

constructed

vectors;

discontinuity

to intersection

end end The

ringframe

patches

procedure

as follows:

ring.frame.patches

begin for

each curve

in fuselage-cross-

section

do

begin calculate

4 inward

B_zier

representation section length

point

place

patch

point

in direction

, two vectors

in direction patch

using

of one-third

curve,

ring frame-width calculate

curves

Hermite on fuselage-cross.

of normal

at

of ringframe-width

of normal;

from

4 curves;

in linked

list;

end end

7

Conclusion

The

algorithms

sections mentioned tation

described

engineers

will be placed Actual

are provided The

in Appendix

complex,

may and

the

a user

needs

represent the

has been

being

of the

A of this

SMART

in the

feedback

from

positive.

The

developed display

current the

cross-

previously

final implemen-

structures showing

portion

these

results

paper.

can

be a very

to specify

a simple

implemented

extremely

the currently

of the user

reverse

been

preliminary

of software

Getting

reflect

cations

within

and

"snapshots"

development

evolution.

have

of SMART

NASA

of SMART.

truly

just

portion

long

and

sometimes

his or her requirements

can

be extremely

concept

is also often

37

yet true.

such

frustrating.

the implementation This

project

has

difficult that

they

The

specifi-

may

be very

added

a new

dimesion sign phases more

to SMART of aerospace

expediently

and should vehicle

enable

the

designing

research

and

development

in the future.

38

and testing

of the de-

to be accomplished

MASTER

PROJECT

Generating The Complete Control Environment Inferface for EASIE

by Chia-Lin

Tsai

Project Advisor: Dr. James L. Schwing Associate Professor of CS

Computer Science Department Old Dominion University Norfolk, VA 23529 April

1992

ABSTRACT

The

Znvironment

_xecution, design of

of utility

mode

quickly

the

of

supports

a central two

provides

data,

provides

depth

control

these

modes

and

a full of as

the

rapid

EASIE

of

sufficient

menu

action

items,

executing

guidance and

execute

Executive allowing

Users

can

This

project

will

this

project

are

and

a menu-driven

with

interface

is and

database,

(ADE),

process.

results

integration

modes

Control

and

conceptual the

users

executive

needed.

of

relational

Complete

design

needs

programs.

basic

select

programs,

_ntegration

integrating

analysis

which

with

which

review

which

(CCE), users

switch

consider

in-

between the

CCE

interface. Two

selecting

will

task

about

users

application

the

face

the

meet

Application-DerivedExecutive

execution

mode

to

programs

provides

_oftware

designed

engineering

of programs

operations:

to

that

stand-alone

execution it

was

engineers

many

a set

EASIE,

for_pplication

objectives menus

selecting be

by

of using

structures

implemented

in the

a windowing of

the

selecting

X window

ii

system

system,

to and

redesign to

menus. OSF/Motif

the

reorganize The

project version.

CONTENTS

PAGE

ii

ABBTI_CT CONTENTS LIST 1

2

OF

iii FIGURES

iv

AN INTRODUCTION TO THE F_BIE 1.1 Why EASIE was developed 1.2 What EASIE was 1.3 What two operation modes 1.4 What CCE mode was A COMPARISON BETWEEN THE AND THE DESIGN PRINCIPLES 2.1 Be consistent 2.2 Provide feedback 2.3 2.4 2.5 2.6 TWO 3.1 3.2

BYBTEM

of

EASIE

1 I 1 2 2

were

CURRENT EASIE SYSTEM ..........................

Minimize error possibilities Provide error recovery Accommodate multiple skill Minimize memorization OBJECTIVES Redesign Reorganize

................

3 3 4 4 4 5 5

levels

OF THIS PROJECT ..................... the selecting menus the selecting structures

6 6 8

4

AN OUTLINE OF THIS PROJECT ......................... 4.1 A general view 4.2 Improvements 4.3 A sample session using the CCE mode 4.4 A command summary using the CCE mode

10 10 12 13 17

5

CONCLUSION

21

.........................................

REFERENCES APPENDIX

A:

State-transition

APPENDIX

B:

User

APPENDIX

C:

Sample

APPENDIX

D:

manual

Programs

screens and

diagrams of

this using

files

iii

of

this

project

project the of

CCE

this

mode project

of

this

project

LIST OF FIGURES

PAGE

Figure

1

WorkSpace

2.

Basic

Control

Environment

menu

9

e.ooo,oooo_eeoooo..oooooo

easie.input

File,

iv

............

11

1.

AN INTRODUCTION

1.1

WHY

E_IE

The

_nvironment

Execution, design of

that

stand-alone

need

for

Research

Center's

WHAT EASIE

uniform

task

meet

and

the

of

_ntegration

needs

tools

the

results

stemmed

activities

Division

and

conceptual

programs has

engineering Systems

of

integrating

analysis and

access

to

The the

solution to

the

_oftware

with

[REF

9].

from

the

Langley

(SSD).

WAS

uses

techniques

the

most

iterative

through

programs

predominant One

quick,

data.

design

progresses

application

refined

a

system

technique.

successive

increasingly

via

of

EASIE

to

analysis

facilitates

process. In

supports central in

application automatic program a

face

interface.

final

aid

to

Space

provides

methodology

this

designed

techniques

design

EABIE

l_pplication

engineering

such

aided

1.2

for was

engineers

computer

a

DEVELOPED

EASIE,

many

The

_

OF THE EASIE SYSTEM

design.

addition, rapid

EASIE integration

relational the

is

and

of

programs,

EASIE the

and and

a

of

utility

execution

review

EASIE

provides

1

of steps both

which about

utilities

tasks:

coordination of

programs

provides

and

logging

programs

of

following

modification

definition

Therefore,

set

database.

execution

execution

a

data executed a

which

selection of

program files

of data, during

throughout

methodology

a

and

set

of

software

coordinating

1.3

TWO

OPERATION

The

guidance

items,

execute

full

design

are

sequence allows

the

results these the

1.4

modes

WHAT

CCE

MODE

CCE-mode

operating

system

can line.

be

This

of

data,

users

user

second which

using

project

will

of

provides

a

a

and

can

of

techniques design

sequence.

iteratively Users

action

control

CCE,

the

with

mode

establish

re-execute input

menu

in-depth

to

(ADE),

users

select The

when

executing

review

switch

consider

This the

between

redesigning

interface.

The

multitude

the

of

provides

(CCE),

interaction.

as needed.

task

codes.

modes

programs.

automatically

minimum

CCE-mode

review

example,

refine

the

Executive

which

Executive

allow

to

basic

allowing

For

engineer

with

quickly

interface

then

analysis

two

mode

Control

which

and

with

application

process.

provided

and

ease

_pplication-_erived

to

Complete

executive

the

first,

to

EASIE

execution

sufficient

execution,

OF

users

menu-driven

and

design

MODES

provides

operations. a

programs

engineering

EASIE

is

utility

of issued Various

WAS interface without

files, via

provides requiring

directories, menu

levels

or

selections of

menus,

available.

2

or

the

flexibility

the

user

data. typed

display,

to

In

CCE,

in

via

and

of

help

an

track

a

commands a

command text

are

2.

A COMPARISON

BETWEEN

AND THE DESIGN

To

design

number

of

human

error

2.1

factors

above

model,

of

the

have

been

portion

help

fully

is

to

error

recovery,

memorization.

in

[REF

8]. significant

in

let the

good

feedback,

buried

problems,

a

ensure

provides

utility

consider

provide

minimize

EASIE

respect

interface

menu

position at

a

within

logically

us

the

current

consider

EASIE

each

interface.

and

commands

such

can as

consistent.

fixed

be

used

Help,

always

menu,

and when

characters whenever

Status,

conceptual

hardware in

binding

the

output

displayed

in

the

same

is

being

Cancel

can

portion same

messages

are

codings

are

the have

input

the

input, be

in

the

considering always

text and

3

The

system-status

place,

addition,

keyboard

and

example,

are the

In

EASIE,

function

For

items

employed. of

is

sequencing,

uniform.

the

relative

always

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functionality,

EASIE,

shown

more

these

with

and

to

CONSISTENT

First,

EASIE

levels,

this

see

to

provide

discussed

however, To

BE

are

have

consistent,

above,

interface. the

be

skill

described

we

which

possibilities,

are

functionality;

interface,

design:

multiple

As

of

a

principles

user

human

principles

in

accommodate These

good

design

minimize

EASIF. SYSTEM

PRINCIPLF

a

factors

THE CURRENT

same global

invoked

ab

any

time,

are

provided

EASIE

and

generic and

can

PROVIDE

FEEDBACK

Feedback

can

corresponding

as

Hove,

to

any

type

applied

EASIE

be

to

functional

of

interface

sequencing

is

Copy, of

and

Delete

object

in

example,

user

when

2.3

MINIMIZE

an

Users of

The

system

the

the

Cancel, provides

thus

EASIE

provides

some

word

of

provide

is

the

accepted

functional

input by

the

feedback,

communicated

to

the

processing.

input

tries

to

there

may

Correct. Cancel

not

input,

etc.)

acknowledgement

errors

interface

important

the

each

the

POSSIBILITIES

ERROR

and

when

and

Currently,

keyboard

object,

does no

to

levels,

sequencing,

satisfied. as

is

make

user

PROVIDE is

is

ERROR

how,

It

EASIE

operation

will

job

matter

such

there

possible

design.

restricted

position,

However,

three

hardware-binding,

is trivially

(command,

system.

at

user-interface

feedback

language

given

the

levels

hardware-binding

2.4

be

such

system.

2.2

for

commands

to

minimize be

some

in any

minimize the

system, error

errors

error

as

occurred

and

it

is the

possibilities. possible. in

the

No

future.

RECOVERY to

provide

error

Unfortunately, feature.

recovery: EASIE

Undo, currently

Abort, only

2.5

ACCOMMODATE User

interface

accommodate help,

multiple

not

skill

some

not

does

which

the

about

how

a

interface

use

commands.

to

extensibility

which

functionality

to

combinations

new

does

users

productive options, going

2.6

EASIE

final

principle

memorization.

on

facility. full

user

a add

primitive additional

new

commands the

which to

down

For

explanation

offer

and

used

these

EASIE

can

allow

start

with

specialized

as

doing

specifying commands,

or

procedures.

MEMORIZATION

system

commands

interface

hiding

bogged

start-up

EASIE

Finally,

commands

infrequently

the

defining

complexity

becoming

complicated

MINIMIZE

by

basic

without

learning

The

not

work

through

minimize

learn

but

a

commands.

provide

next,

give

the

provides

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does

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interface

interaction it

help

not

EASIE

existing

not

to

detailed

means

the

of

interface

Thirdly,

does

however,

faster

to

help

prompts,

Secondly,

what

sufficiently

to

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are

ones.

suggest

EASIE

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accelerators,

which

sufficient.

offer

example,

to

be

complexity.

slower

is

can are

hiding

replace

generally

not

which

accelerators

that

prompts

LEVELS

levels

and

provide

techniques

SKILL

methods

extensibility,

does

are

MULTIPLE

seems a

of The

to

complicated

be

user

interface

original

redundant. menu

to

economic.

5

configuration A

get

design

new

what

user is

is

to

of has

needed.

to

the read It

is

3.

TWO OBJECTIVES

There

are

selecting the

menus

3.1

using

of

a

structures

this

project:

windowing

redesign

system,

according

to

the

and

the

reorganize

design

principles

above.

REDESIGN

THE

Redesign

of

(CCE)

mode

OSF/M0tif

SELECTING the

will

be

skill

to

_omplete

the

in

the

initial

This

EASIE

X

we allow hide

_xecutive

window

menus

will

system:

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the

selection,

windows.

in

the

implemented

numerical

be

level

of

Since

with

menus

MENUS

menus

version.

alphabetical those

objectives

by

selecting

outlined

of

two

OF THIS PROJF.,C'T

system,

of

CCE

want

to

the

mode

are

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complexity

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have

a

the

user. Window-based feature

of

expect

all

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most

computer

The of

software

X

user

that

the

to

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window

X

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relinking

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protocol application.

6

beginning

to

Massachusetts

industry-standard to

portable

and

common

user-friendly at

an

addition, text

X

are

programmers

In

the

become

polished

is

that

containing

users

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allows

protocol.

windows that

have

(MIT),

interfaces

7]

and

System,

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sophisticated supports

to

Technology

system

[REF

systems,

applications

interfaces. Institute

interfaces

to

X

allows

develop any

programs

graphics without X

system

on

any

modifying,. is

based

on

a

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that The

toolkit

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of

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to

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on

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the

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behavior.

It

writers

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the

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style

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the

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TPL,

Selection Edit system editor for certain operations. /tmp_mnt/home/tsai_c/project/proc.PROC types: LOG, PROC, TPL

Change Description Used to change a file description of the indicated object by using the system editor. Form: CD Example: CD TPL /tmp_mnt/home/tsai_c/project/tpl.TPL Allowable object types: APPL, CFG, ITPL, OTPL, PROC, TPL, WS

Orqanize CP

at

as the template.

Used to invoke a Form: ED Example: ED PROC Allowable object CD

file

database. program, "view" of is defined

Example: Allowable

-

PROC

Review

Used to read a workspace, program Form: RD

ED

TPL,

Used to review data from the configuration This command invokes the interactive "REVIEWER" and will display for possible modification a configuration database. A view of a database

Read

Update

CFG,

/tmp_mnt/home/tsai_c/project/proc.PROC types: LOG, PROC, BAT, FILE

Form: RVU Example: RVU IDB Allowable object types: RD

WS,

Selection

Form: Example: Allowable RVU

N WS object

Copy Used Form:

Selection

to

copy one CP

file to

another. 19

a

Example: CP CFG /tmp_mnt/home/tsai c/project/cfg.CFG /tmp mnt/home/tsaic/project/configuration.CFG Allowable object types: APPL, CFG, PROC, TPL, WS, RM

FILE

- Remove Used to remove a file from the user's file directory. Form: RM Example: RM CFG /tmp_mnt/home/tsai_c/project/cfg.CFG Allowable object types: APPL, CFG, PROC, TPL, WS, FILE

SA

- Save Used to save the Form: SA Example: SA PROC Allowable object

CN

work.

- Change Name Used to change the name of a file as indicated. Form: CN Example: CN TPL /tmp_mnt/home/tsai c/project/tpl.TPL /tmpmnt/home/tsai_c/project/template.TPL Allowable object types: APPL, CFG, PROC, TPL, WS,

Execute EX

indicated object for the later /tmp mnt/home/tsaic/project/proc.PROC types: PROC, WS

-

Selection

Execute Used to execute procedure command Form: EX Example: EXAPPL Allowable object

SUB

FILE

an indicated application program file. /tmpmnt/home/tsaic/project/appl.APPL types: APPL, PROC

or

-Submit Used submit a job for batch processing. Form: SUB Example: SUB APPL /tmp mnt/home/tsai_c/project/appl.APPL Allowable object types: APPL

Print PR

Selection

- Print Used to print an indicated file at a local printer. Form: PR Example: PR LOG /tmp_mnt/home/tsai_c/project/log.LOG Allowable object types: LOG, PROC, BAT, FILE

PRVU

- Print Review Used to print a template Form: PRVU Example: PRVU IDB Allowable object types:

or

a view

IDB,

ODB,

2O

of

TPL

the

hard

database.

copy

5.

CONCLUSION

EASIE the

is

needs

alone of

of

consisted

conceptual

engineering

the

EASIE

and

the

well-organized. give

a

considered

in

system,

a

design

is

At concept principles,

the

the

redesign

to

hide

reader mode

to

general and

Although

stand-

selecting

selecting of

menu

users.

menu

menu

this

are

project

This

implemented

the

the

in

not is

to

project the

X

of

the

introduction

current of

and

from minimize concept

some we

paper

EASIE this

By

the

system

is

window

EASIE and

project,

of

menus the

EASIE

this

reorganize

the

and

an

user.

using To

the we

some

a

general

to

the

design

some

flaws.

got are

to

windowing

system

the

Finally, modified

redesign

structures.

reorganize

we

EASIE

is

selecting give

the

system

did.

functionality 21

a

selecting

memorization. about

reader

project

the by

the

comparing

current

improvements enhance

gives

system.

that

selecting

complexity

a

is

objectives

menus

is

the

objectives

EASIE

two

the

structures

the

many

meet

alphanumerical

purpose

by

this

found

selecting

the

the

to

project.

we

Therefore,

and

between

beginning,

about

To

for

two

this

the

EASIE

organized

comparison

of

of main

needs

Since are

the

programs

who

programs.

mode,

principles,

outline

utility

version.

paper

system,

CCE

CCE

of

engineers

structures

to

OSF/Motif This

the

end

set

interface

Thus,

front

a

design

analysis

original

selection,

of

to

the

current

in

EASIE in

system

this

in

project.

format;

does

not

suggest

that

we

may

level widget

be of as

more

mode,

the

the

can

still file

will

minimize

the if

not

menus

to

choice

be of

menu.

22

put

in

the

of

the

buttons

first

level

correct This

Second,

pull-right

choices

bugs

well.

checking.

some

the

be

potential

perform

levels

we

some

must

file-existence

organizing

the

are

input

system

provide

pull-right pushing

there

First,

otherwise,

project

It

CCE

in in of

menus. the the

second pop-up

pull-right

we

REFERENCES

[REF Inc., for 1990

i] X XlI,

...... Toolkit release

[REF 2] Foundation,

, by the Intrinsics 4,

Staff of Reference

Volume

five,

O'Reilly Manual,

O'Reilly

...... , OSF/Motif Style Prentice-Hall, Inc., New

[REF 3] A1 Kelley C, second edition, Inc., California,

and The 1990

[REF 4] Brian W. Proqramminq Lanquaqe, Jersey, 1988

[REF 5] Brian W. Kernighan Environment, Prentice-Hall, [REF 6] Dan Heller, Version, Volume Six, Inc., 1991

& Associates,

Guide, Jersey,

Ira Pohl, A Book Benjamin/Cummings

Kernighan second

Software

On C Proqramminq in Publishing Company,

Pike, The New Jersey,

Proaramminq edition,

[REF 7] Douglas A. Young, The Applications with xt, OSF/MOTIF New Jersey, 1990 [REF 8] James D. Foley, and John F. Hughes, Practice, second edition, U.S.A., 1990

Open 1988

Inc.,

and Dennis M. Ritchie, The C edition, Prentice-Hall Inc., New

and Rob Inc.,

Motif Motif

and Associates, second edition

X

UNIX Proqramminq 1984

Manual O'Reilly

Window edition,

For OSF/MOTIF & Associates,

System Proqramminq Prentice-Hall,

and Inc.,

Andries van Dam, Steven K. Feiner, Computer Graphics: Principles and Addison-Wesley Publishing Company,

[REF 9] James L. Schwing, Lawrence F. Rowell, and Russell E. Criste, The Environment for Application Software Integration and Execution fEASIE) Version 1.0 Volume III Proqram Execution Guide, NASA TM-I00575, National Aeronautics and Space Administration (NASA) Langley Research Center, Hampton, Virginia, April 1988 [REF i0] Software,

Joseph Prentice

S. Dumas, Hall, New

Desiqninq Jersey,

[REF ii] Samul P. Harbison and Guy Manual, 3rd edition, Prentice-Hall, [REF 12] William M. Newman and of Interactive Computer Graphics, Book

Company,

U.S.A.,

1979

23

L.

User

Interfaces

1988 Steele Jr., A Reference Inc., New Jersey, 1991

Robert F. Sproull, second edition,

Principles McGraw-Hill-

for

Master's Project Report

Application

Driven Interface for EASIE

Advisor-

Generation

Dr. James L. Schwing

Apri_2Z, 1992 Department of Computer Science Old Dominion University Norfolk, VA 23529 - 0162

ABSTRACT The Environment interface

for Application

and a set of utility programs

programs

about

execution.

a central

relational

Software

which support database.

One of them is a menu-driven

(ADE),

which

provides

execute

an application

(CCE),

provides

with sufficient program.

an extended

Integration

the rapid integration

EASIE

execution guidance

and Execution,

provides

mode,

called

to review

interface

which

and execution with two

a menu

called Complete

allows

provides

basic

Application-Driven

data, select

The other mode of execution, executive

users

EASIE,

a user

of analysis modes Execution

action-item, Control

in depth

control

techniques

only.

of

and

Execution

of the

design

process. Currently, of this project in a window

the EASIE system to extend system.

in the generation

is based alphanumeric

the flexibility

Secondly,

of an ADE

of the EASIE

a set of utilities application.

interaction system

in the ADE

will be developed

mode

It is the purpose

by implementing

to assist the experienced

engineer

it

Table

of Contents

1. Introduction 2. EASIE:

ADE-modc

2.1 Concepts 2.2 Sample

Considerations

of EASIE system Session

for ADE mode

2.3 Menu Manipulation 2.4 The Drawbacks 3. Principles

in ADE mode

of EASIE in ADE mode

of Interface

4. Modification

Design

of EASIE in ADE mode

4.1 W'mdow System: 4.2 Design

and Construction

OSF's MOTIF

Considerations

4.3 Demonstration

for ADE Facilitator

of the ADE Facilitator

5. The General Stmcmm

of Solution

5.IData Structure 5.2 Mechanisms 5.3 Capabilities

and Limitations

6. Conclusions 7. References Appendix:

program

Listing

of ADE Facilitator

I. Introduction The Environment for NASA

for Application

by Old Dominion

Branch of NASA

Langley,

the task of coordinating EASIE provides and execution with two

engineering

called Complete

Control

in depth control

of the design

directly typed.

known

In general,

process.

system.

the EASIE

study through

system addresses

represents

the execution

to this evaluate

the design

"EASIE

users"

system

programs

against

a final solution

easily

programs

its objectives.

are responsible

used in the engineering engineers".

design

a basic

viewing,

manage

[1].

EASIE

sufficient

program.

provides mode,

guidance

The other mode

executive

interface

can be issued

access

and analysis

system

users called

to review

of execution, which allows

via menu

system,

the EASIE

programs

EASIE

will be referred

its input

selection

or

it also is complicated via the menw-driven

the design

They

of users who be involved

design

to this group as

these users are only interested

system

in

[1]. programers"

and improvement

EASIE

experts

the design

of data required

will refer

to as "application

process.

are the

and the generation

documentation

for the development design

Tiffs group conducts

In general,

and output variables

method

used by engineers applications

user tools

and editing

classes

of modeling

documentation

with respect

or "experts". and

will refer to this

to particular

application

[1].

Considerations

through successive

provides

programs,

with

the engineer/designer/analyst.

aided by EASIE

2. EASIE : ADE-mode

EASIE

to ease

system.

into an EASIE

and can defines

The predominant

design

installed

as "experienced

programs

utility program

execution

of an operating

or, more often, as "designers".

already

group

programs

group

users

the needs of two different

of modeling

These programers/engineers analysis

database

commands

the flexibRity

Analysis

which support the rapid integration

an extended

Most users currently

and Vehicle

is a menu-driven

an application

In CCE,

developed

as ADE.

The first classification

A second

Corporation

which

codes.

provides

(CCE), provides

in the buildup and use of an engineering

executing

of them

which

CCE provides

to use like an operating mode

One

EASIE,

and a set of software

and analysis

and execute

Execution

Although

Sciences

about a central relational

(ADE),

a menu action-item,

and Execution,

and a set of utility programs

of execution.

Execution

Computer

design

programs

modes

Integration

with a methodology

a user interface

Application-Driven dam, select

University,

provides

of analysis

basic

Software

which

of program

environment

and data with the existing

is the iterative

of analysis support

data.

by providing environment.

techniques

the selection

EASIE

technique.

to increasingly and

also provides

the ability

One processes

execution tools

to quickly

ref'med data. of application

for a design

integrate

to

new

team t_ analysis

2.1 Conceptsof EASIE system Conflmn'atlon l)nts: Configur_ion in_facc

data is stored in a systc_

dmbase.

is that data held in the database are anatomically

appUcadon program in an appropria_ made, a copy database

of this "master"

is provided

for review, database

formal

database

on a "read

communicated

is placed

only" basis.

m either a user or an

in a controlled

project

directory.

That is, the users may display

only by the design

user

Once the basic dam definitions and values have been

or they may make copy of the database

can be entered

An advantage of the F._Sm

for their personal

manager

Access

to this

the configuration

files.

Updates

dam

to the master

[1].

Reviewer: The EASIE software

interface

data. Based upon an indicated REVIEWER, to retrieve

provide analysis

using information the necessary

a program program

contained

called the "REVIEWER"

or other dataset in the database

in the database,

input and present

which can access

can then make

any

for a designer,

the appropriate

the

selection

that data at the terminal

Rm.._.ii_tteg The software data templates.

screen forms used to control A data template

by a given Frogram EASIE

process

a list of all data required for input (or supplied

as output)

modify

access

data formats.

to these

the variables

Since

data templates

in the database

data templates

arc generated

is used in conjunction

when

presented

by

with the

during the Review

[1].

FORTRAN

the Formatter

subroutine allowing

2.2 Sample Menu

Session

displayed

interaction

for ADE during

code, called Forma_r data or store

Derived

It consists among

an ADE session

code,

the automatic

generation

of

which can be placed in the application

data into the database

during program

Executive

are typically

of steps to conduct

(ADE)

mode.

for a given application.

these programs

created by experienced some particular

user can easily learn to manipulate

of four short programs

Within the concepts

to enable

execution.

mode

an introductory

with EASIE

relationship

uses the data templates

the proper sequence

such an interface, the AppLication

source

it to retrieve

new users through

system

Finally,

to directly

A final utility called

program

are ca/led

along with their required

utility program.

REVIEWER

is basically

the flow of data to and from the database

Now

we look

This example

that define

and draw

design

activity.

data and execute at an example

illustrates a box.

engineers

capabilities Figure

to guide Given

programs

to describe

in an

of the EASIE

1 represents

the basic

and their data.

of the EASIE system,

we can realize this figure

in a straight forward manner.

Default (pmtecled)

Drawlt ........i:_/iiiilj

Dmwin

tal_s x,y.z

.. .-.

Drsw

!

Boz Progrsm

Boxout t

Figure

.z

vo_umo

I.

Flow

Diagram

For

Sample

Z

Session

Using

EASIE

:'