Development of Software Using Visual Basic for Learning Aerospace Structure Theory

7/29/2019 Development of Software Using Visual Basic for Learning Aerospace Structure Theory

http://slidepdf.com/reader/full/development-of-software-using-visual-basic-for-learning-aerospace-structure 1/8

Research Paper

10th

National Aeronautical Conference 20-21 April, 2006 PAF Academy Risalpur 101

DEVELOPMENT OF SOFTWARE USING VISUAL BASIC FORLEARNING AEROSPACE STRUCTURES THEORY

Farrukh Mazhar a, Abdul Munem Khan b, Irfan Aziz c and Omar Bashir

a Department of Industrial Engineering, College of Aeronautical Engineering, National University of Science andTechnology, Rawalpindi, Pakistan.

b Department of Aerospace Engineering, College of Aeronautical Engineering, National University of Science andTechnology, Rawalpindi, Pakistan.

c Department of Mechanical Engineering, University of Engineering and Technology, Peshawar, Pakistan.

d Department of Avionics Engineering, College of Aeronautical Engineering, National University of Science andTechnology, Rawalpindi, Pakistan.

AbstractLast Century had seen remarkable changes in the field of Science and Technology;

particularly computers. Computer is no doubt the biggest ever invention of mankind. Advancements in the field of software industry has brought into many revolutionary changes inthe field of computers. Today, the most developments are being done in the field of transformation of engineering concepts into software form. The requirement of simple and easylearnable software was always felt at the undergraduate level at CAE (NUST College of Aeronautical Engineering, Risalpur, Pakistan), for better understanding / application of the coursecontents in structures specialty. To meet these requirements, authors have developed FARST(Farrukh’s Structural Tool) software that can be described as “Computer -based Learning Tool”.Students can use this tool to understand and analyze basic and medium level aircraft structuresproblems. The computer code is written in Visual Basic

®. This language is selected for its user-

friendly environment and easy to use Graphical user interface (GUI).

Keywords: Structures, Software, Computer-based Learning Tool, Aircraft Structures

1. List of symbols

A AreaC ConstantE Modulus of ElasticityI Moment of InertiaM MomentP ForceT TemperatureX Displacement in X axisY Displacement in Y axisZ Displacement in Z axisα Coefficient of Thermal Expansionσ Stress* Modulus Weighted Property

2. IntroductionThis is computer era. Integration of

theoretical concepts into software is theneed of today. Extensive mathematicalcalculations in engineering design / analysishave asked for an enormous requirement of engineering softwares to facilitate andreduce the workload. Same was the aimbehind this paper. It has always been

desired to have a software, which canintroduce the basic concepts of Structures,and perform lengthy calculations in a muchsmaller time at undergraduate level.

FARST®

can be briefly described as“Computer -based Learning Tool”, able tocompute and analyze basic and mediumlevel aircraft structures; covering thestructural aspects of the course contents atCAE. FARST

®is written in Visual Basic

©.

Visual Basic©

language is selected for itsuser-friendly environment and enhancedGraphical user interface (GUI) control.

2.1 Selection of Programming LanguageInitially, FARST codes were planed to

be written in FORTRAN which, however, didnot provide user friendly GUI. Also, the user had to provide several data files whoseformat was not always intuitive and their preparation was sometimes tedious. Thenovice user would find this task rather daunting and may have discouraged himfrom using the software altogether. Thus,the need for a user interface became



Research Paper

10th


apparent. Asking a software developer toadd a GUI application in a commonlyaccepted form to avoid many of the abovedescribed difficulties. Hence, in FARST

®

software development, Visual Basic®

foundto be more helpful and dynamic as far as thesimplicity and user friendly nature isconcerned. Moreover, Visual Basic® provedto be excellent in the development of GUI. InFARST

®all data is inputted and displayed

through the GUI environment and plotted intwo-dimensional graphical format, wherever required.

2.2 FARST’s Aim.FARST

®is developed, with the following

aims in mind:-(a) To develop a software to facilitate thecomputational facilities at CAE.(b) To cover the structural aspects of the

course. Enable students to familiarizethemselves with the modern computationalfacilities.(c) The software has to be as user-friendlyas possible and should be able to cover allthe aspects of modern computationalsoftware.(d) The software should be robust andmulti-dimensional. It should have a widespectrum of application and potential for subsequent development.(e) Gives flexibility to the user in terms of material, geometry, loads selection so that

they can study as well as understand their impact on the results and ultimately assiststhem in subsequent design process in thelonger run.

2.3 Application.FARST

®is capable to perform the

following tasks:-.(a) It can analyze simplified or mediumcomplex structures, used in aircraftconstructions like skin panels, fuselagecells, wing sections and other similar structures.

(b) It can analyze the affect of longitudinalstresses, compression forces, bendingmoments, and thermal loading on all suchstructures.(c) The calculations are performed bydividing the structure into longitudinalmembers, and nodes for simplicity.(b) Performs lengthy calculations on suchstructures in seconds with reliable results

and therefore helps in structural levelunderstanding / diagnostics.(d) It also displays step-wise results as wellas graphical representation of the results for ease of comprehension.

2.4 Sequence of Development of FARST ®

Following sequence is followed duringthe course of FARST

®development;

(a) Understanding of the Course material.(b) Learning of Visual Basic

®programming

[4], [5] and [6].(c) Integrating theoretical concepts inFARST

®in the form of code and GUI

development [4], [5] and [6]. .

3. Theoretical Aspects of FARST ®

FARST

®deals with application of the

theory /analysis of bending / extensions of the beams and structures.

The theory of elasticity results intopartial differential equations and the solutionto these equations exists only for a relativelyfew cases. Approximate solution can befound by the Rayleigh-Ritz or FiniteDifference methods; but such computationsare very lengthy and intricate. FARST

®is

therefore, based upon concepts given inreferences [1] and [2], a brief introduction isgiven in the following paragraphs.

3.1. Stress Resultants. Assume that the force and moment

resultants of the stress are acting upon thecross sections of the beam, as shown in thefigure 1. The stresses on the differentialarea dA at point B with co-ordinates (x, y, z)

are xx, xy, and xz. The resultant of thesestresses on the cross section consists of aforce and a moment, whose components areaxial component P, and shear componentsVy

and Vz, and the moment components are

tortional moment Mt, and bending momentsMy, and Mz, which are about axes their parallel axes. The outcome of all calculationcomes out to be following equation (the

detailed equations development may foundout as given in reference [1]):-

z I I I

I M I M y

I I I

I M I M

A

P

E

E

yz zz yy

yz z zz y

yz zz yy

yz y yy z

xx 22

1 *)(**

****

*)(**

****

*

*

3.2. Modulus Weighted Section properties

The coordinates of modulus -weightedcentroid are given as:-



Research Paper

10th


Which reduces ton

i

iio A y A

y1

0*

*

1*

n

i

iioo A z A

z 1

**

1*

Also

)(2

11

*

ii y y

in

i

y y A z I E

E I

iooo

)(2

11

*

ii z z i

n

i

z z A y I E

E I

iooo

)(11

*

iii z yi

n

i

z y A y z I E

E I

iooo

And

**)(**2 A z I I o y y yy oo

A y z I I

A y I I

oo z y yz

o z z zz

oo

oo

****

**)(** 2

3.3 Buckling and Principal Force calculationThe second part of FARST

®deals with

the calculation of critical force of Bucklingand calculation of stress resultants inprincipal and oblique planes from equationsgiven in [1], [2] and [3].

4. Solved ExampleThe figure 2 is a simplified representation

of the construction used in the aerodynamicsurfaces of flight vehicles. The beam is

subjected to the temperature and a bendingmoment of 10 6

in-lb.The assumption is that the compression

skin remains unbuckled. To simplify thecalculation the structure is idealized intolongitudinals that carry only axial stressesand webs that sustain only shear stresses.

The skin and spar webs are divided intosegments and lumps the area of eachsegment at its centroid (fig 3). A largenumber of segments are to obtain a goodapproximation of the moment of inertia withthis method. The various inputs to thestructure are:

(a) The coefficient of thermal expansion is1.26E-5

oF

(b) The initial temperature of the structureis 70

oF

(c) The external load is zero.(d) The moment about x-axis is 1E6 in-lb.(e) The moment about Y axis is zero.(f) The net area A*= 1.797E+1 in

2 .

(g) The coordinate of centroid are(20.90in and 5.215in).(h) The values of the moment of inertiaabout different axes are ;

I xx *= 4.247E+2 in4,

I yy *= 7.063E+3 in4,

I xy

= -4.705E+2 in4

The equivalent thermal loads areP* = P + P T = 6.943E+5 lb.M x *=M x + M xT = 1.445E+6 in-lbM y *=M y + M yT = 1.146E+5 in-lb

The constants areC 1= 3.863E-3C 2 = -2.622E-5 C 3= -3.693E-4

The value of xx/E is given as

xx /E = C 1 +C 2 x I +C 3y I - T

The detailed results are given in table 1and table 2. It may be highlighted that theresults are verified to be accurate to almostdouble in accuracy as compared to manualcalculations or calculations done by Excelspreadsheet; since the code is programmedusing double precision (64 bits long)numerals.

5. Organization of FARST ®

5.1. Introduction

FARST software consists of three major parts as:

(a) Shell Stress Analysis (Core of thesoftware)(b) Buckling Analysis(c) Principal Forces calculation

5.2. Splash Screen. The first screen of FARST is following splash screen.

5.3. Title page. It is the menu selectionscreen, giving three options to the user:-

(a) Main Menu

(b) Tutorial(c) Exit

5.4. Main Menu. It gives following choices tothe user based upon the type of analysis.

(a) Shell Stress Analysis(b) Buckling Analysis(c) Principal Force



Research Paper

10th


5.5. Input Form. It selects the no of nodes of the structure (limit is 20 nodes).

5.6. Data Input Forms. It enables the user toinput coordinal data along with appliedforces.

5.7. Result Form. It displays the finalresultant stresses at each node. Step bystep results of calculation along with the plotof structure can also be displayed usingfollowing options:-

(a) Detailed Analysis(b) Plot(c) Back

5.8. Detailed Analysis Form. It displays thestep by step calculation results.

5.9. Buckling Analysis. It calculates the

critical force of buckling to buckle a beam asper end conditions.

5.10. Principal Forces. It calculates theprincipal stresses and stresses in obliqueplane.

6. ConclusionIn this paper, the integrated software

FARST®

(Farrukh Structural Tool) has beenpresented that enables the user to developan understanding of medium advancedaircraft structures analysis. As over the

period of time a dire need of a software wasfelt which can familiarize the students withthe computational / analytical aspects of thecourse, since the equations involved arevery complex and intricate and to solve asingle problem number of classes would berequired leaving behind the analyticalaspects untouched. For practical utility of theconceptual approach of the course contents,it is deemed necessary that a GUI interfaceto be designed to enable the handling of

massive amounts of data inputs andgraphical displays of output. In particular,the GUI presented for the FARST

®program,

has been written in an object-oriented formatusing Microsoft Visual Basic

®Language.

Microsoft Visual Basic®

was chosen since itis powerful and flexible and produces aninterface with the familiar Windows look andfeel.

Although detailed code of FARST®

wasnot presented in this paper due to limitedspace, however, the software was tested for several problems and results obtained werealso authenticated manually and usingMicrosoft Excel

®spreadsheets, validating

software’s double-precision accuracy; sincecode is programmed using double precision(64 bits long) numerals.

Like all other software this effort is notthe end and there is still a lot of room for

future growth and development in FARST, interms of its course contents coverage aswell as applications.

7. References

[1] Rivello, Robert M., “Theory and Analysisof Flight Structure”, McGraw-Hill, 1969.

[2] Higdon, Archie, “Mechanics of Materials”, John Willie & Sons, 1985.

[3] Coultas, H. W., “Theory of Structures”,Pitman and Sons Ltd., 1963.

[4] Michelle Moore, “Learn Visual Basic®

Today”, IDG Books, 1995.

[5] Cornell, Gary, “Visual Basic®

for Windows Handbook”, McGraw-Hill, 1993.

[6] Petroutsos, Evangelos, “MasteringVisual Basic

® 6”, Sybex

Computer Books, 1998,



Research Paper

10th


Fig: 1 Stresses and Stress resultants on abeam cross section

Fig: 2 Actual Structure on the top andidealized structure at the bottom

Fig: 3 Idealization of a web

Node Ai

in2

Xcood

xi in

Ycood

yi in

T0F

E/E* A*

in2

Ax

in3

Ay

in3

Asqx

in4

Asqy

in5

Axy

in6

X

in

Y

in

Tt0F

1 3 0 12 300 0.95 2.85 0 34 0 410.4 0 -20.94 6.78 230

2 0.49 0 9.47 275 0.96 0.47 0 4.5 0 42.186 0 -20.94 4.25 205

3 0.49 0 2.54 275 0.96 0.47 0 1.2 0 3.0348 0 -20.94 -2.67 205

4 2.5 0 0 375 0.92 2.3 0 0 0 0 0 -20.94 -5.21 305

5 1.09 5.07 0 500 0.8 0.872 4.4 0 22.41 0 0 -15.87 -5.21 430

6 1.09 18.93 0 500 0.8 0.872 17 0 312.5 0 0 -2.011 -5.21 430

7 1.09 29.7 0 475 0.83 0.905 27 0 798 0 0 8.75 -5.21 405

8 1.09 42.93 0 475 0.83 0.905 39 0 1667 0 0 21.98 -5.21 405

9 1.5 48 0 325 0.94 1.41 68 0 3249 0 0 27.05 -5.21 255

10 0.22 48 1.27 250 0.97 0.213 10 0.3 491.7 0.3442 13 27.05 -3.94 180

11 0.22 48 4.73 250 0.97 0.213 10 1 491.7 4.7744 48.5 27.05 -0.48 180

12 2 48 6 300 0.95 1.9 91 11 4378 68.4 547 27.05 0.78 230

13 1.23 42.93 6.63 350 0.93 1.144 49 7.6 2108 50.282 326 21.98 1.418 280

14 1.23 29.07 8.37 350 0.93 1.144 33 9.6 966.7 80.138 278 8.12 3.15 280

15 1.23 18.93 9.63 375 0.92 1.132 21 11 405.5 104.94 206 -2.01 4.41 305

16 1.23 5.07 11.37 375 0.92 1.132 5.7 13 29.09 146.29 65.2 -15.87 6.15 305

Table 1 : Detailed Resultant (Part :A)



Research Paper

10th


T E Tpsi

E TAlb

E TAxin-lb

E TAy in-lb C2x C3y xx /E xx psi

2.90E-03 2.89E+04 86722.6 -1816097.5 588719.68 0.000525 -0.00239 -9.926E-4 -9.926E+3

2.58E-03 2.60E+04 12757.9 -267169.96 54330.182 0.000525 -0.0015 2.566E-4 2.592E+3

2.58E-03 2.60E+04 12757.9 -267169.96 -34082.44 0.000525 0.000942 2.815E-3 2.844E+4

3.84E-03 3.71E+04 92808.4 -1943542.9 -483668.1 0.000525 0.001838 2.493E-3 2.419E+4

5.42E-03 4.55E+04 49607.2 -787337.99 -258526.3 0.000398 0.001838 7.855E-4 6.598E+35.42E-03 4.55E+04 49607.2 -99782.085 -258526.3 5.04E-05 0.001838 4.221E-4 3.545E+3

5.10E-03 4.45E+04 48475.1 424572.64 -252626.8 -0.00022 0.001838 4.712E-4 4.099E+3

5.10E-03 4.45E+04 48475.1 1065899.3 -252626.8 -0.00055 0.001838 1.078E-4 9.379E+2

3.21E-03 3.17E+04 47568.4 1287134 -247901.4 -0.00068 0.001838 1.865E-3 1.846E+4

2.27E-03 2.31E+04 5081.90 137509.09 -20030.16 -0.00068 0.00139 2.341E-3 2.388E+4

2.27E-03 2.31E+04 5081.90 137509.09 -2446.765 -0.00068 0.00017 1.063E-3 1.085E+4

2.90E-03 2.89E+04 57815.1 1564393.2 45589.186 -0.00068 -0.00028 -3.563E-5 -3.563E+2

3.53E-03 3.45E+04 42374.6 931756.99 60109.866 -0.00055 -0.0005 -7.653E-4 -7.500E+3

3.53E-03 3.45E+04 42374.6 344444.6 133841.72 -0.0002 -0.00111 -1.044E-3 -1.024E+4

3.84E-03 3.71E+04 45661.7 -91846.035 201758.04 5.04E-05 -0.00156 -1.559E-3 -1.512E+4

3.84E-03 3.71E+04 45661.7 -724717.99 281209.5 0.000398 -0.00217 -1.838E-3 -1.783E+4

Table 2 : Detailed Resultant (Part :B)

Fig 4 : Block Diagram of FARST ®

Splash Screen

Main Menu

Shell Stress Analysis Buckling Analysis

Result

Normal and Shear Stresses

Coordinate Input

Node Selection

Detailed Result

Plot

End Conditions

Data Input

Result

Principal stress Oblique Plane

Data Input

Result

Data Input

Result



Research Paper

10th


Fig 5 : Splash Screen

Fig 6 : Title Page of FARST ®

Fig 7 : FARST ®

Main Menu

Fig 8 : Node input

Fig 9 : FARST ®

Data input

Fig 10 : Result Window



Research Paper

10th


Fig 11 : Detailed Structural Analysis

Fig 12 : Plot of Structure

Fig 13 : Selecting End Conditions For Buckling Analysis

Fig 14 : Principal Stresses

Documents

Development of Software Using Visual Basic for Learning Aerospace Structure Theory