Aircraft design and analysis systems (ADAC)

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1°010)1

Aircraft Design and Analysis System

(ADAS)

Bibliotheek, TU Delft

1111I1111111

C 3021885

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Series 02: Flight Mechanics

02

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Aircraft Design and AnalysisSystem

(ADAS)

C. Bill/F. van Dalen/A. Rothwell

Delft University Pre ss / 1997

2392

331

7

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Published and distributed by:

Delft University Press

Mekelweg 4

2628

CD Delft

The Netherlands

Telephone

+ 31 (0) 15 278 32 54

Fax

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e-mail: DUP@DUP.TUDelft

.

NL

by order of:

Faculty of Aerospace Engineering

Delft University of Technology

Kluyverweg

1 P.O.

Box

5058

2600 GB

Delft

The Netherlands

Telephone

+ 31 (0) 15 278 14 55

Fax

+31 (0)152781822

e-mail: Secretariaat@LR.TUDelft.NL

website: http

:

//www.lr

.

tudelft.nl/

Cover: Aerospace Design Studio,

66.5 x

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Fer Hakkaart, Dullenbakkersteeg

3, 2312

HP Leiden

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The Netherlands

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+

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Copyright ©

1 997

by Faculty of Aerospace Engineering

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No part of the material protected by th is copyright notice may be

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and retrieval system, without written permission from the publisher: Delft

University Press.

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Part 1 Aircraft Design and

Analysis System (ADAS)

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A-43: FXINTL: Interpolate on a polyline AM: FXLENG: Calculate the length of a polyline A-45: SX2000: Interface to B2000 finite element code A-46: SXFINI: Assign attributes to fmite elements A-47: SXFLEN: Generate loading conditions A-48: SXINTH: Initia1ize element thicknesses A-49: SXLOAD: Apply loads to fmite-element model A-50: SXMASS: Create structura1 mass points A-51: SXMA1L: Define material properties A-52: SXPLFR: Plot nodal forces

A-53: SXPLNR: Plot element normal vectors A-54: SXPLOR: Plot element orientation veclOrs A-55: SXPLTH: Plot element thicknesses A-56: SXPRES: Plot pressures on elements

A~57: SXPRMA: Print mesh area data A-58: SXSORT: Son element nodes A-59: SXVONM: Plot Von Mises stresses B-I: Appendix B: Common block descriptions. B-2: Common block CXAIRI

B-3: Common block CXAIRF B-4: Common block CXA TMO B-5: Common block CXCGLO B-6: Common block CXCONN B-7: Common block CXCONS B-8: Common block CXCROS B-9: Common block CXELEM B-I0: Common block CXENG2 B-ll: Common block CXENGC B-12: Common block CXENGD B-13: Common block CXENGF B-14: Common block CXENGL B-15: Common block CXFINI B-16: Common block CXFLEN B-17: Common block CXFNCN B-18: Common block CXFUSC B-19: Common block CXFUSG B-20: Common block CXFUSS B-21: Common block CXffi..DS B-22: Common block CXLOAD B-23: Common block CXLSG I

B-24: Common block CXL VU B-25: Common block CXMASS B-26: Common block CXMA1L B-27: Common block CXMESH B-28: Common block CXNACG B-29: Common block CXORGN B-30: Common block CXPV AR B-31: Common block CXPVNM B-32: Common block CXSKIN B-33: Common block CXSOLN B-34: Common block CXSOLV B-35: Common block CXSTVR B-36: Common block CXWGT2 A-53 A-54 A-55 A-56 A-57 A-58 A-59 A-61 A-62 A-63 A-64 A-65 A-66 A-67 A-68 A-69 A-70 A-7l A-72 A-73 A-75 B-I B-2 B-3 B-4 B-5 B-6 B-7 B-8 B-9 B-IO B-ll B-12 B-13 B-14 B-15 B-16 B-17 B-18 B-19 B-20 B-21 B-22 B-23 B-24 B-25 B-26 B-27 B-28 B-29 B-30 B-31 B-32 B-33 B-34 B-35 B-36

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C-I: Appendix C: AutoPLOT command descriptions. C-2: Command CARI C-3: Command CARP C-4: Command CD (Unix) C-5: Command CONT C-6: Command DAT A C-7: Command DV AR C-8: Command FV AL C-9: Command LPQ (Unix) C-IO: Command LPR (Unix) C-II: Command LPRM (Unix) C-12: CommandLS (Unix) C-13: Command MKDIR (Unix) C-14: Command MV (Unix) C-15: Command PWD (Unix) C-16: Command QillT C-17: Command RM (Unix) C-18: Command SURF C-I C-2 C-3 C-4 C-5 C-6 C-7 C-8 C-9 C-IO C-12 C-13 C-15 C-16 C-17 C-18 C-19 C-20

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1. Introduction.

This manual is a quick-start users guide for the Aircraft Design and Analysis System (ADAS), a computer-based tooi for aircraft design. The ADAS system provides a computer environment wherein design data and analysis methods cao be easily manipuiated. Automated functions for routine tasks speed-up or simplify the design process, while sufticient flex-ibility is retained to make ADAS applieable to a wide range of design problems. This manual refers to tbe ADAS version appropriate for student project work. This version runs on low-cost workstations and does not rely on tbird party software, except AutoCAD or other CAD-sYStemS supporting AutoCAD's Data Exchange Format (DXF).

It is assumed that tbe ADAS-user has average experience in Fortran programming and worlcing witb AutoCAD. Using ADAS effectively also requires basic knowledge ofthe Unix operating system and reiated programs, e.g. file management commands, vi-editor, source-Ievel debugger, etc. Where appropriate tbe user is referred to generally available literature for further information.

This manual bas been updated based on work carried out in the framework of a joint research project between the aircraft design group (A2), tbe structural design groop (C) and the National Aerospace Laboratory (NLR). The objective of this project was to extend the ADAS-system to incorporate preliminary structural design eapability based on tinite-element techniques (refs. 13,14,15,16). New subprograms in this release are subprograms which allow the user to develop a de-sign-specific a fini te-element model generation program based on structural elements specified in the configuration drawing. Subprograms with names starting with SX .... are intended to semp a proper interface between the finite-element model and a structural analysis program, i.e. 82000 (see section 6). These programs have been developed by ir. F. van Dalen. Finaily, this ADAS-version has been upgraded to AutoCAD release 12 (refs. 8,9) and the ADS optimization pro-gram (ref. 20) has been implemented. The next release of this manual will include descriptions of new aircraft design modules which over the years have been developed as part of student thesis work (refs. 17,18,19). These programs have been reviewed and properly documented by E. de Jong.

2. The ADAS system general architecture.

Figure 1 give a schematic representation of tbe ADAS system architecture. It identifies the major ADAS components and

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Executive Program ... Figure 1: ADAS system architecmre.

• DSPROG (design program) is the name of a user-supplied Fortran subprogram which contains the algorithm 10 solve a particuiar design problem. DSPROG may eall subprograms available from tbe program Iibrary. Tbe program Iibrary represents a method base witb standard analysis methods and utility routines which can be used as building blocks to develop more complex design programs. The contents of the program library is regularly upgraded to incorporate new requirements and to accommodate advances in design technology.

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• Geometry infonnation is represented by a3-view configuration drawing created with the CAD-program AutoCAD. An interface program (DXDXFI) is available 10 transfer significant geometry infonnation from the AutoCAD-drawing and the ADAS intemal geometry representation via a Data Exchange Fonnat (DXF)-file. Non-geometry data are stored in regular text files.

• The ADAS Executive Program controls the processing of !he design program DSPROG. The user can select oneof three control modes: analysis mode, parametric survey mode or optimization mode.

• AutoPLOT is a self-contained program that can generate severa! types of XYZ-plots from genera! parametric data. The graphs are reproduced in AutoCAD.

The physical implementation of ADAS in files and directories is shown in Figure 2. All files are read-only for the genera! Ivol/adas

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/common lengine lairfoil

Figure 2: Implementation of AD AS files and directories.

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AutoPLOT adas.(\ adas libadas.a adas.dwg

user. The files denoted with an asteriks (*) are executable programs and can he invoked by simply typing the program name,optionally followed by arguments. To avoid having to give the full pathname it is recommended to append the di-rectory Jvol/adas to the command path defined in your .login file or to create a command alias. To list the files in a didi-rectory type:

Is directory

In the following sections the ADAS system components and their usage will he discussed in more detail. 2_1. The design program (DSPROG).

As mentioned in the introduction, the user provides the computer-program 10 solve the design problem, while !he ADAS-system takes care of the actual execution. In principle, ADAS does not impose a priori restrictions on the structure or com-plexity of the design program. Fortran-77 is used as the standard programming language. Users unfamiliar with Fortran program ming are referred to one of the many textbooks available of the subject, e.g. ref. 6. Sun Microsystems have their own set of Fortran manuals (ref. 7) which are useful for quick reference. The vi-editor is available for textprocessing. The user-supplied design program must he provided in the fonn of a subprogram with a fixed name: DSPROG. The gen-eral structure of this subprogram must he as follows (Figure 3):

subroutine dsprog (fv,obj,co,pv,icall) dimension fv(20),co(20),pv(20)

_____________________________ 1Iii" Fortran statements go here

return end

_____________________________ 1Iii" O!her subprograms may follow

Figure 3: The design program (DSPROG) structure.

It is imperative that one adheres to this convention in order to properly link the design program to the AD AS-system. For example, one can choose different variabie names, but the data types and the order in which they appear in the parameter list must not he changed. The significance of the variables in the parameter list will he discussed in Section 3. The design

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program source code is saved in a file progfile.f in the user directory. The filename is arbitrary but must contain the J suf-fix. This file may optionally contain other user subprograms.

2.2_ The program library.

To avoid having to re-code a design program for commonly used design calculations, the ADAS-system provides a pro-gram library of subpropro-grams which may be referenced within DSPROG. The subprograms are pre-compiled and the ob-ject codes are stored in archive format in the file fvol/adas/libadas.a. To list the contents of the program library type: ar t fvol/adas/libadas.a

The subprograms in fvol/adas/libadas.a provided for general use are described in appendix A. These subprograrns make extensive use of common blocks for inter-subprogram data exchange. The common block definitions are retained in sep-arate files in the directory fvol/adasfcommon. Appendix B contains common block descriptions. To ensure consistency in naming variables and common blocks, it is recommended to use the compiler directive:

inelude 'common'

in the user source code, where common is the file containing the required common block. The compiler will automatical1y insert the specified file before compilation. It is important to correctly setup data interchange otherwise unexpected results may accur. Throughout ADAS standard Fortran conventions are used for variabie names and their associated data types: by default all variables with names beginning with I, J, K, L, Mor N are IN1EGER*4 and allothers are RE AL *4.

2.3. Compile, link and run.

When coding of a design program is completed, it can subsequently be compiled and linked to the ADAS Executive Pro-gram. This is done automatically with the command:

adasdsprog

where dsprog is the name of the file containing the design program source code, but without the .f suffix this time! The design program is compiled and the object code is linked to the ADAS Executive Program resulting in a problem-depend-ent executable file called dsprog in the user directory, as shown in Figure 4. To subsequproblem-depend-ently execute the program, simply

design program source file Program Library executable file

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dsprogJ dsprog.o dsprog

Figure 4: Create a problem-dependent ADAS executable program.

type the name ofthe executable file: dsprog, and the program starts executing instantly. If programming errors were found or extemal references remained unresolved, dsprog wiU not be created or will not run. Correct the errors first.

By default, monitoring output is printed in the window from which the process was initiated. To save output, redirect it to afile, i.e.: dsprog > file (file is overwritten) or dsprog » file (file is appended). Output does not appear on the screen in this case. If you wish to save output and simultaneously view it on the screen, redirect output to the TEE-program with a pipe connection, i.e.: dsprog I teefile

3. ADAS control modes.

Figure 5 gives a flow diagram representation for the ADAS Executive Program. The design program DSPROG is called

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new values for survey variables eaU dsprog icall = 1 yes eaU dsprog ) 0 - -.... 101 icall = 2 no optimizer eaU dsprog

1'40---icall = 3 Mo _ _ _ ....fcall dsprog caU dsprog ieaU= 5 icall = 4

--....;~~ design point ljllalysis mode _ _ .... ~~ optimization mode _ _ ... ~~ parametric survey mode

Figure 5: ADAS Executive Program con trol flow.

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at several 'strategic' locations at each instance with a ditlerent value lor the variabie icall to allow the user to structure computations. For example, input and output operations are typically done once at the beginning and the end of the pro-gram respectively, i.c. for ieaU = 1 and ieall = 5. The user can set the executive propro-gram to run in one of three modes: 1. Analysis mode.

In analysis mode the design program is executed in a single pass. This option is typieally used fordesign-point calcu-lations on a given aircraft configuration.

2. Parametric survey mode.

In parametric survey mode, the design program is successively called withdifferent values for selected design param-eters. Parametric survey mode is generally used to determine the influence or sensitivity of design characteristics (de-pendent variables) with respect to design parameters (independent variables).

3. Optimization mode.

In optimization mode, control is passed to the Automated Design Synthesis (ADS) program (ref. 20) for optimizing a (linear or nonlinear) objective function subject to (linear or nonlinear) constraints by variation of selected design

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pa-rameters (free variables). Contrary to parameter variation, optimization mode results in one (optimum) design. Option 2 and 3 may be combined.

Which control mode to select depends largelyon the kind of design problem, e.g. the number of design parameters, wheth-er sensitivity information is required, the complexity of the analysis methods, the demand on computing resources, etc.

The following Sections will describe how a particular con trol mode can be selected. 3.1. Analysis mode.

ADAS operates in analysis mode by default, i.c. the design program DSPROG is not subject to any special control algo-rithm within ADAS. Anaysis mode is therefore typically used 10 perform design-point calculations on a given aircraft con-figuration.

3.2. Parametric survey mode.

To switch ADAS 10 parametric survey mode, one must supply information on the survey variables. The usual way is 10 read this information from a file with the subprogram DXISRV. The subprogram DXISRV reads the values for the survey variables and sets ADAS automatically to pararnetric survey mode. DSPROG will be called as many times as there are data rows in the input file. With each pass the next row of values is passed to DSPROG through the PV-array. The element-number in PV corresponds with the column-element-number as defined in the input file. ADAS expects DSPROG to return values in the PV-elements associated with the dependent variables. Note that ADAS does not make a distinction between depend-ent and independdepend-ent variables, this should follow from the context in DSPROG.

3.3. Optimization mode.

With numerical optimization an optimization algorithm is invoked which attempts to find the minimum or maximum value of a specified objective function and subject 10 constraints. The independent variables are referred to as free variables. The way-1O select optimization mode is basically similar 10 that of parametric survey mode. An input file must be prepared which contains information on the free variables, constraints and objective function. The subprogram DXIOPT reads the input file and automaticaUy sets ADAS 10 optimization mode. The optimizer will call DSPROG (with icall = 3) as many times as is required 10 reach the optimum, this includes caUs to construct gradient vectors based on finite differences.The values of the free variables for the current iteration step are passed to DSPROG through the FV-array. They may not be changed! ADAS expects DSPROG 10 return the corresponding values of the constraints and the objective function in the CO-array and the OBJ-variable respectively. The optimization program is based on ADS and the user's manual (ref. 10) should be consulted for information on the available optimization strategies.

4. Creating a DXF-file from an ADAS/AutoCAD-drawing.

When an ADAS/AutoCAD-drawing is completed, it can be translated into DXF-format and stored in a file which is ac-cessible by the DXDXFI subprogram. A DXF-file is created with the DXFOUT-command. This command prompts you for additional information:

File name <drawing>:

You must specify a name for the DXF-file 10 be created. AutoCAD automatically adds the suffix .dxf. The default drawing is the name of the current drawing. The next prompt is:

Enter decimal places of accuracy (0 to 16)jEntities/Binary <6>:

You should not specify Binary because the DXF-file must be in ASCII. Select Entities, which gives you the option 10 select particular elements in the drawing. In principle it is only necessary 10 select those entities of which geometry information is required by your analysis program. However, in the unfortunate event that you forget 10 select an essential element the analysis will most probably fail. It is therefore suggested select all elements in the drawing, e.g. by using the window op

-tion. The foUowing prompt is:

Enter decimal places of accuracy (0 10 16)/Binary <6>:

Again, do not specify Binary. Now you can select the accuracy, i.e. the number of decimal digits, 10 represent coordinate values. The default is 6. The selected elements are translated into DXF-format and placed in the specified file.

S. Creating XYZ-plots with AutoPLOT.

The AutoPLOT-program can be used 10 create XYZ-plots from general parametric data. The process of creating a graph requires 3 steps:

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1. Within AutoPLOT parametric data is extracted from a file.

2. One of several available plot types is selected and AutoPLOT creates the graph in the form of a Data Exchange Format (DXF).

3. Within AutoCAD, the DXF-file is read to visualize the graph. The graph cao be edited and plotted as a regular Auto-CAD drawing.

The parametric data must be provided in a file with a tabular format conform Table I. The fust line contains the column headers (S 15 characters) separated by one or more spaces and terminated with a slash (f). The maximum number of col-umns is 20. The following lines must contain the corresponding data values. There may be upto 2 independent variables. Jf there are more, you must reduce the dependency, for example by copying a data subset to a new file with the vi-editor. For certain types of graphs, such as contour and surface plots, only data with 2 independent variables is allowed and f(x,y) must be a rectangular grid fix x ny S 2500, i.e. the same x-values should be present for each y-value. The order in which data values are placed in the input file is not significant as AutoPLOT automatically sons data prior to plotting. To start type:

AutoPLOT

AutoPLOT wil! return with the prompt: AutoPLOT>

At this point the user cao enter any of the following commands: command data quit carp cont earl surf dvar fval description

Extract parametric data from a specified file Exit AutoPLOT.

Create a general plot f(x) or f(x,y). Create a contour plot f(x,y).

Create a plot f(x) versus g(x) or f(x,y) versus g(x,y). Create a 3-dimensional plot f(x,y)

Specify explicit plot boundaries (disable/enable auto-sealing) Specify contour levels for contour plotting.

lf the command is not any of the above listed, AutoPLOT will assume it is an operating system commando The specific

AutoPLOT commands are discussed in detail in appendix C. For convenience a description of the most frequently used Unix commands have also been included. A useful primer for Unix commands is ref. 21.

Jf a plot command is given, AutoPLOT writes out the plotting inslrUctions to the DXF-file with a fixed name: file.dxf in the users directory, wherefile is the file containing the parametric data. Iffile.dxf exists it wil! he overwritten. The DXF-file should subsequently be read into AutoCAD with the DXFIN-command to display the graph.

6. ADAS structures module: description of the analysis or stresses, displacements and constraints. This section describes the analysis of the ADAS finite element model and the post-processing of the results. 6.1. Finite element model generation

In order to create an ADAS finite element model, the subprogram DXCROS is used to create clusters of shell and beam elements (so-called mesh areas) respectively. The syntax is as follows:

call dxcross (nb,kk)

where nb represents the identification label of the generated elements. The designer controls an element 's branch, structure type, structural function and material by selecting the appropriate value of nb. The value of nb affects all the elements in one mesh area. It is assem bied from the following sub-labels:

-Branch number

-Structure type number -S tructural function nr. -Material number (2 digits) (2 digits) (2 digits) (I digit)

In addition, nb may be positive (to indicate'wetted' elements) or negative (to indicate intemal structure). In assembling the identification number, the user may select branch numbers, structure type numbers etc. from the following cataiogue: Branch numbers:

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Ol. 02. 03. 04. 05. 06. 07.

OS

.

Main lifting surface; top side Main Iifting surface; bottom side Fuselage

Vertical fin; top side Vertical fin; lower side Horiwntal stabilizer;'top side' Horiwntal stabilizer;'lower side'

Branch connecting elements Structure type numbers:

Displacement constraint 00

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02 03 04 05 06 07

Blade stringer stiffened skin (awaits implementation) Z-stringer stiffened skin

Hat stringer stiffened skin Stiffened shear web Bar element Truss rib Plate rib

Structure type numbers (continued): 08

09 10

Plain sheet material FIoating frame FIexible sheet material Structural function numbers:

Ol

02 03 04 05 06 12 13 14 15 21 22 23 24 25 31 32 33 34

35

99

Stressed wing skin Wing spar Wingribs Wing leading edge Wing trailing edge Pressilre cabin skin Cabin floor Cockpit floor

Forward pressure bulkhead Rearward pressure bulkhead Stressed fin skin

Fin spars Fin ribs Fin leading edge Fin trailing edge Stressed stabilizer skin S tabilizer spars S tabilizer ribs S'tabilizer leading edge Stabilizer trailing edge Unspecified Material numbers: I 2 Example: A12024-TI A17075-T6

When a mesh area is generated using the label nb = -0204031 this means that all elements in that mesh area will belong to the branch'main lifting surface; lower', that they will he of the stiffened shear web type, that their function will he that of a wing rib, and that they will he made of AL 2024-T3.

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In order to create a finite element model of the physical properties that correspond with the selected structure types and materiaIs, the following subroutines must be called:

SXFINI

SXSORT

SXMA1L

SXIN1H

A short description of these subroutines follows below:

The subprogram SXFINI is similar to subprogram DXELEM. Coincident nodes are removed as in DXELEM, and shell and bar elements are given their element node numbers ij (ne). i2(ne). i3(ne) and i4(ne) where ne is the element number. The mesh area label nb(i) ofmesh area i is broken down into element labels nbr(ne). nSI(ne), nse(ne). nml(ne) and nma(ne)

which identify an element's branch number, SInlCture type, structuraI component, material and the mesh area to which it belongs respectively. Triangular shell elements with 'two coincident nodes are degenerated into proper three-noded ele-ments for which i4(ne) = O.

The subprogram SXSORT corrects the supposedly random element orientation according to the elements ' structuraI com-ponent number. The orientation of element ne is defined by the position of the element nodes relative to each other. SX-SORT first ensures that the vectors between nodes ij (ne )-i2 (ne) and i3 (ne )-i4( ne) oppose each other 's direction (see figure below; this does not apply to three-noded elements). If they do not, the values of i3(ne) and i4(ne) are swapped. The ele-ment normal vectoris defined by the cross product of the vectors between nodes iJ (ne)-i2(ne) and ij (ne)-i4(ne). The ele-ment normal vector should point outward to the wetted side of the skin. If this is not the case, nodes i2(ne) and i4(ne) are swapped. Finally, the vector between nodes iJ(ne)-i2(ne) is aligned with a component's main axis by rotating the nodes around the element (as exact alignment is generally impossible, maximum dot product of element vector with branch axis is used as the a1ignment criterion).

The subprogram SXMATL stores all necessary material data in common block CXMATL. In addition to this, materiaI property modification factors are defined for each available structure type. These modification factors serve, for in stance, to eliminate the shear and transverse stiffness of element layers representing stringers.

The subprogram SXINTH initializes all element thicknesses and stiffener pitches to a non-zero value. Minimum allowable thicknesses are also defined for the benefit of the design process.

6.2. Load analysis

In order to perform a stress analysis of the model, the aircraft loads must first be determined. This can be done by running the following subroutines:

SXFLEN

SXPRES or DX0215 SXMASS

SXLOAD

A short description of these subroutines follows below:

The subprogram SXFLEN generates loading conditions according to FAR23 or FAR25 regulations, for a selected com-bination of aircraft weight and altitude. Both manoeuvring and gust loads are evaluated. For each loading condition nld,

the equivalent airspeed V(nld), the normal load factor n(nld), the fuselage incidence alfa(nld) and the Mach number

rmaeh(nld) are stored in common block CXFLEN. The logical variabie aelive(nld) activates or de-activates each loading condition.

The subprograms SXPRESS and DX021S both calculate the statie aerodynamic pressures press(i.lde) acting on element i, for each loading condition lde which is active. However. SXPRESS is based on the simple Died erich's Iifting line meth-od, while SX021S is a relatively involved panel method. For aerodynamically conventional designs, it is recommended to use the much faster SXPRESS subroutine, but when for instance a canard configuration is analysed, SX0215 is required to account for the interaction of multiple Iifting surfaces.

The subprogram SXMASS breaks down the mass of each element into discrete nodal masses pmass(in) and evaluates the various inertia properties of the model.

The subprogram SXLOAD applies the pressures press(i.lde) to the finite element model, to create loading condition lde.

Four-noded elements are temporarily broken down into two three-noded elements, the nonnal vectors of which are calcu· Iated, and the pressure is converted into discrete nodal forces P(inj.lde) where in indicates the node number,j indicates the X, Y or Z-component of P, and lde indicates the loading condition number. Inertia forces are applied to all nodal masses

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evaluated in SXMASS, in order to ereate statie equilibrium. 6.3. Analysis

or

stresses and displacements

Stresses and displacements may be analysed by a eall to subprogram SX2000. The subprogram SX2000 ereates an input file ftlename.inp for tbe finite element programme 82000, containing eommands for element generation and loading as specified by tbe user witb various AD AS subroutines. One tbing the user does NOT have to define is the way in which the model is supported. SXGFfS automatically applies symmetry conditions to nodes on tbe piane of symmetry, and supports the foremost and reannost points on tbe plane of symmetry to prevent rigid body motion. Whenfilename.inp has been completed, an optimization input file will be generated autornatically so that tbe structure optimization module B20PT rnay be run. The arguments in tbe caII to SX2000 control which B2000 modules are run or whether instead analysis results are simply being read from a previously generated B2000 database. In either case, SX2000 will read the stresses and

dis-placements from the B2000 data base and store them in the eommon block CXSOLN. .

6.4. Post-p~ocessing

For tbe graphical representation of the finite element results, a number of subprograms are available that write graphieal data in DXF format.

The subprogram SXVONM writes,tbe deformed structure to the currently opened DXF file,. The elements are given a eolour that represents the Von Mises stress criterion in the required element layer (skin or stringers).

The subprogram SXPLFR writes tbe forces aeting on the structure in a particular loading case to the eurrently opened DXF file. The loads are represented by red lines.

The subprogram SXPLNR writes the normal vector on each element to the currently opened DXF file. The normal vectors are indicated by yellow lines. If the subprogram SXSORT has been used, all normal vectors should point to the outside of the aircraft model.

The subprograrn SXPLOR writes the orientation vector (defined as running from node I to 2) of each element to the cur-rentlyopen DXF file. The orientation vectors are indicated by green lines.

The subprogram SXPLTH writes the structure model to the currently opened DXF file, with each element given a color that represents the total equivalent thickness (skin plus stringers) of the element.

Should the user require numerical data on a particular mesh area, such as stresses, thickness etc., these may be obtained by a caII to subprogram SXPRMA. This subprogram will write all data concerning a given mesh area to the screen. 7. Rererences. 1. Bil, C.: 2. Bil, C.: 3. Bil, C., Middel, J.: 4. Bil,C.: 5. Bil,C.: 6. Merchant, Ml.: 7. An.: 8. An.: 9. An.: 10. Kent, Dorothy

Aerodynamic Analysis Integration in a Computer-Based Aircraft Design System, paper 3A-3, proceedings International Aerospace Congress, Melboume 1991.

ADAS: A Design Systemfor Aircraft Conftguration Deve/opment, Al AA-paper 89-2131, Seat-tie 1989.

Some new developments on the Aircraft Design and Analysis System (ADAS), ICAS-paper 90-2.6.4, Stockholm 1990.

Applications of Computer-Aided Engineering to Subsonic Aircraft Design in a Universiry En-vironment, ICAS-paper 86-3. l.l , London 1986.

Development and Application of a Computer-Based Systemfor Conceptual Aircraft Design, ISBN 90-6275-484-8, Delft University Press, Delft 1988.

Fortran 77, Language and Style, ISBN 0-534-00920-4,Wadsworth Publishing Company, Bel-mont 1981.

Sun Fortran Manual Set, part land Il, Sun Microsystems, March 1990.

AutoCAD release 12 Command Reference Manual, AutoDesk Publication 00104- 010200-5020, Autodesk Ltd., Guildford, 19 August 1993.

AutoCAD release 12 User's Guide, AutoDesk Publication 00104-010200-5160, Autodesk Ltd., Guildford, 24 June 1993.

AutoCAD Reference Guide, ISBN 0-934035-02-4, New Riders Publishing, Gresham, Oregon,

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1991.

11. Chasen, S.H. Geometrie Principles anti Procedures for Computer Graphic Applications, ISBN

0-13-352559-7, Prentice-Hall, Inc., Englewood Cliffs, New Jersey, 1978.

12. Hordijk, R.R.: Inleiding in het gebruik van AutoCAD, Handleiding LR-I09, Faculteit der Luchtvaart- en

Ruimtevaarttechniek, Technische Universiteit Delft, Delft 1992.

13. Boer, A. de: Modifications in B2000 for the benefit of ADAS, NLR CR-92246L, National Aerospace

Labo-ratory NLR, The Netherlands, 16 June 1992.

14. C. Bil, et al. Structural Optimization in Preliminary Aircraft Design: - A Finite-Element Approach -, NLR

1P-92459L, National Aerospace Laboratory NLR, The Netherlands, 5 November 1992.

15. Arendsen, P. The B2000 Optimization Module: B20PT, NLR TP-94116L, National Aerospace Laboratory

NLR, The Netherlands, 18 March 1994.

16. Arendsen, P. et al. Finite-Element Based Preliminary Design Procedures for Wing Structures, NLR TP-94450L,

National Aerospace Laboratory NLR, The Netherlands, 1 November 1994.

17. Reijm, M.M. Ontwikkeling van een ADAS-subroutine om operationele kosten, return on investment en

min-imaal benadigde inkomsten te berekenen, Afstudeerverslag, Faculteit der Luchtvaart- en Ruimtevaarttechniek, Technische Universiteit Delft, Juni 1993 (in Dutch).

18. Sepulveda H, S.A. ADAS implementatie van een semi-empirische methode voor de berekening van draagkrachts

-, weerstands- en momentencoefficient bij getrimde of ongetrimde condities, Afstudeerverslag, Faculteit der Luchtvaart-en Ruimtevaarttechniek, Technische Universiteit Delft (in Duteh).

19. Paulzen, K. Gewichtsschattingsmethodes voor subsone verkeersvliegtuigen voor het ADAS-

onlWerpsys-teem, Afstudeerverslag, Faculteit der Luchtvaart-en Ruimtevaarttechniek, Technische Univer-siteit Delft, augustus 1994 (in Duteh).

20 .

Vanderplaats, G.N. ADS - A Fortran Programfor AutomatedDesign Synthesis. Version 2.01, Engineering Design

Optimization, Inc., Santa Barbara (CA), January 1987.

21. Haanschoten, M. Users Quick Reference Guide: Unix on Sun Workstations, intemal document, Faculty of

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A-I: Appendix A: Sub program descriptions

By convention, ADAS subprogram names have 6 characters. Subroutine names start with DX •••. , real functions start with

FX ..•. and integer functions start with IX .•.. Each subprogram description contains the calling sequence a short explanation of its purpose and a description of the global variables, i.e. those in the parameter list and in the common blocks. Local

variables are not listed. For each variabie, its name, data type and a short description is given. Input variables (I) must

have a value at the time the subprogram is referenced. Output variables (0) will have a value upon return of the

subpro-gram. For variables in common only the common block name is given. Refer to the appropriate common block description

for information on the variable.

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A-2: DXAFEM: Write finite-element model to a DXF-file

Syntax: call dxafem

Purpose:

The subprograrn DXAFEM saves a FE-model in the DXF-file currently open, i.e. the DXF-file must already be open at the time DXAFEM is called. To open aod close a DXF-file use the subprograrn DXDXFO aod DXDXFC respectively.

The image cao subsequently displayed with AutoCAD.

VariabIe Type IlO Description

fx /cxmesh/ fy /cxmeshl fz /cxmesh/ nb /cxmesh/ nbr R*4 Substructure index. nd /cxmesh/ ni /cxmesh/ nj /cxmesh/

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A-3: DXAIRG: Read airfoil geometry from a DXF-file

Syntax:

caIl dxairg (file,n,m)

Purpose:

The subprogram DXAlRG reads the contour coordinates Ia,ya,wa of airfoil section n in lifling surface m from a DXF-file, where wa are the corresponding curve fit factors and na are the number of points read .. The upper (k = I) and lower

xa(i,n.m,k)

upper contour (Ic = I) ya(i,n,m,k)

i= 1 i = na(n,m,k)

(0,0)

lower contour (Ic = 2)

Figure I: Airfoil geometry definition.

(k = 2) contour Hne must be separate POLYLINE-entities placed in layer AlRC_I and AlRC_2 respectively. The airfoil

geometry must be defined in the World Coordinate System (WCS) with the nose point (i

=

I) at (0,0). You can subse-quently use the subprogram DXAIRS to scale the airfoil coordinates according to the local chord length of Hfling surface m.

Variabie Type 110 Description

file CH*(*) 1 DXF-file with airfoil geometry.

m 1*4 1 Lifting surface number.

n 1*4 1 Airfoil number. na 0 /cxairl/ wa 0 /cxairl/ xa 0 /cxairl/ ya 0 /cxairl/ A-3

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A4: DXAlRP: Write airfoil section geometry to a DXF-file Syntax:

call dxairp (n,m)

Purpose:

The subprogram DXAIRP writes the contour lines XlJ(i,n,m.k),ya(i,n,m,k),wa(i,n,mk),i = l,na(n,m,k) of airfoil section n

in lifting surface m to the DXF-file currently open, i.e. the file must already be open at the time DXAIRP is called. The upper (Ic = I) and lower (Ic = 2) contour lines are joined and are represented by a single closed POLYLINE-entity. The POLYLINE is placed in layer O. In addition, a TEXT-entity is written to the DXF-file with insen point at xls(n.m). zl-s(n,m) in view mir(m). The text string is airf(n,m) and is rotated with respect to the insen point by lW(n,m). The TEXT-entity is placed in layer AIRF _Mmm.

Varia bie Type IlO Description

m 1*4 mir n 1*4 na tw wa xa xls xrf ya yrf zls

Lifting surface index. /cxlsgl/

Airfoil section index. /cxairl/ /cxairl/ /cxairl/ /cxairl/ /cxlsgl/ /cxorgn/ /cxairl/ /cxorgn/ /cxlsgl/

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A-S: DXAIRS: Scale an airfoil section Syntax:

eaU dxairs (n,m)

Purpose:

The subprogram DXAlRS seales the coordinates (xa,ya) of airfoil n according to the local chord length of the

corre-sponding lifting surface m.

VariabIe Type 110 Description

m 1*4 1 Airfoil index.

n 1*4 1 Lifting surface index.

na 1 IcxaiIll np 1 Icxlsgll xa IlO Icxairll xls I Icxlsgll ya IlO Icxairl/ A-5

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· '~.~ ,I . . . ~_ . .

A-6: DXAMSH: Read a FE-model from a DXF-file Syntax:

call dxamsh (file) Purpose:

The subprogram DXAMSH opens the DXF-file and reads (part ot) a finite elemenl model. DXAMSH is essentially the

reverse of the subprogram DXAFEM. DXAMSH provides the option lO define a finile elemenl mesh area nd using

stan-dard AutoCAD drawing editing functions and reading il inlo the ADAS internal FEM data struclurefx(i,nd)fy(i,

nd)fz(-i,nd), i

=

l,ni(nd)*nj(nd). If mesh area nd already exisl it will be overwritten, otherwise the mesh area will be added 10 the finite element model. The DXF-file must contain mesh areas represented by a 3D MESH entily and a 3D POLYLINE entity for shell and beam elements respectively. Each entity much have a layer name as SHELL_ruUd or BEAMS_n-d_id, where nd is a 4-digit integer defining the mesh area number and id is a 7-digit integer number representing the cor-responding element lype number. The size of a mesh area is limited 10 ni(nd) x nd(nd) < 65, where nj(nd) = 1 for 3D POLYLINEs. VariabIe

ex

fy fz nb nd ni nj file Type 110 CH*(*) /cxmesh/ /cxmesh/ /cxmesh/ /cxmesh/ /cxmesh/ /cxmesh/ /cxmesh/ Description

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A-7: DXATMO: Calculate atmospheric properties Syntax:

eaU dxatmo (at,ap,ad,ag,as,av,h) Purpose:

The subprogram DXATMO computes ambienl properties al altitude h in the Standard Atmosphere.

ad R*4 ag R*4 ap R*4 as R*4 at R*4 av R*4 h R*4 Subprograms called: exp sqrt 0 Density. 0 Gravitational acceleration. 0 Pressure. 0 Speed of sound. 0 Temperature. 0 Kinematic viscosity. I Altilude. A-7

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. '

,

,-A-8: DXCHST: Write optimization history to a file Syntax:

eaU dxchst (file) Purpose:

In optimization mode, ADAS automatically samples the values of the free variables, constraints and objective function for eaeh major iteration step. The subprogram DXCHST can be used to write out this information to aftle.IC ADAS is used in a combination of parametric survey mode and optimization mode, DXCHST will also write out the current val-ues of the survey variables pv(i,kvc),i = l,npa where kvc is the currenl survey number. The maximum number of iteration steps written is ix < 100. The first line in the file constaints the column headers terminated by a slash (j). The first column is named iteration then followd by the names of the survey variables pn(i),i = l,npa, the names of the free variables fn(i),i

=

l,nfv, the names ofthe constraints cn(i),i

=

I,nc and the name of the objective function on (in that order). The fOllowing linesj = l,ix contain the corresponding values j; pv(i,kve),i = I,npa; fh(ij),i = l,nfv; eh(ij),i = l,ne and oh(j) repectively. Variabie ch en fh file fn ix

kve

ne nfv nob npa oh on pn pv Type CH*(*) 110 /cxchstl /cxcnnm/ /cxchstl Description

Filename 10 write convergence history data. /cxfncn/ /cxehstl /expvar/ /exnfnc/ /cxnfnc/ /cxnobb/ /cxpvar/ /cxehstl /cxfncn/ /cxpvnm/ /cxpvar/

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A-9: DXCROS: Create a new mesh area in a finite-element model Syntax:

eaU

dxcros(nbr,kk) Purpose:

The subprogram DXCROS generaleS a mesh a10ng a surface area (patch) defined by 4 boundary curves using Coons technique.The procedure is illustrated in Figure I: The boundary curvesj

=

1,4 are defined by their point coordinales

inlemalnode

;I

60~ '100 ')-c~rv e ot

Figure I: Definition of a Coons mesh area enclosed by 4 given boundary curves.

x(ij),y(ij),z(ij),i

=

l,nnU) with nn(l)

=

nn(2) and nn(3)

=

nn(4). DXCROS computes the coordinates ofthe inlemal

mesh points by using the subprogram FXCOON to interpolale on the x, y and z-coordinates of the boundary curves respectively. If nn(3) = 1 then DXCROS crealeS a beam element. DXCROS adds the new mesh area to the current mesh areas fx(i),fy(i)/z(i),i

=

ni(nd)+I,ni(nd+l) where ni(nd+ I)

=

ni(nd) + nn(I)*nj(nd+ I) and nj(nd+ I)

=

nn(3). DXCROS sets the mesh area identification number nb(nd+ I) = nbr and increases the total number of mesh areas nd = nd + I. The possible values for nbr are given in section 6.

Variabie fx fy fz kk nb nbr nd ni nj Type 1*4 1*4 110

o

/cxmesh/ /cxmesh/ /cxmesh/ Description

Number assigned 10 mesh area.

/cxmesh/

User label 10 be assigned 10 mesh area. /cxmesh/

/cxmesh/ /cxmesh/

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nn x y z Subprograms called: fxcoon R*4 minO 1*4 /cxcros/ /cxcros/ /cxcros/ /cxcros/

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A-IO: DXCURV: Construct 2 circular arcs between 2 points with given tangents Syntax:

call dxcurv (xl,dxl,yl,dyl .x2,dx2,y2,dy2,xi,yi,wl,w2) Purpose:

The subprogram DXCURV COnsbUclS 2 circular arcs between 2 points (xl,yl) and (û,y2) with given gradienIS

(dxl ,dyl) and (dx2,dy2) respectively. DXCURV iteratively computes an intennediate point (xi,YIJ until me 2 arcs are

blended and returns me corresponding curve fit factors wl and w2.

dxl R*4 dx2 R*4 dyl R*4 dy2 R*4 wl R*4 w2 R*4 xl R*4 x2 R*4 xi R*4 yl R*4 y2 R*4 yi R*4 I I I I 0 0 I 0 I I 0 Gradient dx at point 1. Gradient dx at point 2. Gradient dy at point 1. Gradient dy at point 2.

Curve fit factor for arc I. Curve fit factor for arc 2. X -coordinilte point 1.

X-coordinate point 2.

X-coordinate intennediate point.

Y-coordinate point I.

Y-coordinate point 2.

Y-coordinate intennediate point.

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A·U: DXDXFC: Close

a

DXF·file

Syntax:

calI dxdxfe

Purpose:

The subprogram DXDXFC doses tbe DXF-file eurrently open and automatically writes tbe 4 standard trailing lines required in a DXF·file before dosing ie

o

ENDSEC

o

EOF

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A-12: DXDXFI: Read a design configuration from a DXF·file

Syntax: call dxdxfi (fiJe)

Purpose:

The subprogram DXDXFI reads aircraft geometty infonnation from a DXF·file. The usual procedure to define an aircraft configuration is by creating a 3-view Jayout drawing with AutoCAD, translating the drawing into a DXF·file and the read· ing geometty infonnation from the DXF·file into ADAS with the subprogram DXDXFI •. DXDXFI only extracts geometty infonnation of elements with aspecific Jayer name, allother elements are ignored. Coordinates are automatically re!ated to the appropriate view origin. When DXDXFI finds a significant element it reports the current Jayer name. If DXDXFI fails at some point, this infonnation should make it easy to trace it back to a particular element in the ADASI AutoCAD-drawing.

A typical ADAS/AutoCAD drawing contains a schematic aircraft configuration represented in 3 orthogonal views: top view, side view and front view (Figure 1). The aircraft must be drawn in real-world dimensions (mm), re!ative to the

prop-Figure 1: Example ofan ADAS/AutoCAD design configuration drawing.

er view origin (0,0) indicated by a special symbol (BLOCK-element). To start a new ADAS/AutoCAD-drawing retrieve the drawing /vol/adas/adas.dwg (the suffix .dwg does not have to be specified), which contains these BLOCK-elements at default locations. You are free to move them to make sure the views do not overlap.The aircraft must be defined according to a specitic protocol which stipuJates drawing conventions for each individual element, e.g. layer names, point sequence in a line, maximum number of points, etc. When the drawing is completed a DXF-file is made. The subprogram DXDXFI scans the DXF-file in sequential (top-down) order and makes use ofpre-defined layer names to 'recognize' basic drawing elements, e.g. LINE, POLYLINE, TEXT, etc., as significant aircraft components. Geometty infonnation is stor.ed in com-mon blocks for access by other subprograms. The following section gives a detailed description of the drawing conventions, but first some genera! remarks. As already mentioned, in this context the !ayer name is an important attribute. An ADAS-specific !ayer name is composed from a keyword optionally followed by a string of one or more digits. For

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example, the layer name AIRF _nm is used for airfoil sections where AIRF is the keyword an,d n and m are integer numbers which refer to airfoil section n in lifting surface m. The number of digits allocated for n and m depends on their maximum value. As I $ n $ 11 and I $ m $ 10 the maximum number of digits is 2 for both variables. However, in order to unam-biguously distinguish n and m it is important to use a fixed number of digits for n, e.g. n = Ol for a root airfoil. Since it is the last number in the row this is allowed, but not required, for m, so AIRF _011 = AIRF_O 10 I , but AIRF _11 would be AIRF _1100 which is Dot correct. As a reminder such Iayer names will be given as AIRF _nnmm in this manual. Where indicated, smooth POLYLINEs may be created using the AutoCAD fit-option under PEDIT which constructs piecewise circular are segments passing through user-defined fOints. The user also has control over the local tangents at these points. The curve fit procedure generates an additional control point between each pair of user-defined points, which are not visible to the AutoCAD-user, except with the Iist-command, but will appear in the'DXF-file and consequently will be read by the subprogram DXDXFI. Where the maximum number of points allowed is restricted, these control,points must be included. A curve fit factor w(i) is associated with each point i which controls the shape of the arc segment be-tween point i and point i+ 1. w(i) ::i

°

results in a linear segment. AutoCAD refers to w(i) as the 'bulge' factor. Lifting surfaces geometry and airfoil type definiüon.

A lifting surface is represented by a planform outline drawn in top or side view and airfoil sections defined in side and top view respectively, as shown in Figure 2. The planform of lifting surface m is defined by a POLYLINE xls(i,m),yls(i,m),i

I'

,"(i,m) ,I

1-xls(n,m) yls(i,m) layer: AIRF _nnmm

__

~t_

tw(n,m) >

°

~~==~~~----f

= l,np(m) (common block/cxlsgll) with np(m) $ 22. The sequenceofpoints starts at the apex (i

=

I) and then runsalong the leading and back along the trailing edge. Each point in the leading edge must have a corresponding point in the trailing edge withequal spanwise coordinate yls(i,m). The layer name must be SURF _mm, where m (m $ 10) is defined as fol-lows:

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m = 2: horiwntal tailplane.

m = 3: vertical taiJplane. m = 4: canard.

m = 5: engine pylons (top view) m = 6: engine pylons (side view) m = 7: engine pylons (side view).

Airfoil section n in lifting surface m is defined by placing a TEXT-element in the viewplane perpendicular to the corre-sponding planforrn viewplane. The TEXT-element must have a layer name as AIRF _nnmm. The number of airfoil sections n

'5.

np(m)!2 with n = 1 for!he root airfoil. The coordinatesxls(n,m) and zls(n,m) (common block /cx1sgl/) is taken relative to the lext string reference point To define a twist angle tw(n,m) (common block IcxaiII/), relative to the horizontal, rotate the TEXT-element. The text string is the airfoil designation airf(n,m) (common block /cxairf/). Note that an ADAS/ Au-toCAD drawing only contains a reference to an aiIfoil section. The subprograrn DXAIRG is available to read airfoil con-tour coordinates from a specified DXF-file. How to create such a file is explained in the following section.

High-lift devices geometry definitioo aod positioning.

Within a lifting surface planforrn !he outline of high-lift device n can be defined by a POLYLlNE xhld(i,n),yhld(i,n),i

=

1,4 (common block /cxhlds/), as shown in !he following figure. The maximum number of high-lift devices is n

'5.

10. The

xhld(i,n)

Figure I: High-lift devices geometry and positioning. layer name must be as HLDS_nn.

Cootrol surfaces geometry and positioning.

Within a lifting surface planforrn the outline of control surface n can be defined by a POLYLlNE xco(i,n),yco(i,n),i

=

1,4 (common block /cxcons!), as shown in Figure 10. The maximum number of control surfaces is n < 10. The layer name must be as CONS_nn.

Fuselage geometry definition.

A fuselage is represented by 4 profile lines in top and side view and cross-sections defined in front view as shown in Figure 11. The profile lines xf(i,k),y/(i,k),wf(i,k)i

=

I,nf(k) (common block /cxfusg/) are POLYLINEs with the crown profile line (k = 1) andkeel profile line (k = 2) defined in side view (in the plane of symmetry) and the waist profile line ZX-projection (k = 3) and XY-projectiQn (k = 4) defined in side and top view respectively. The significanee of the waist profile line will be discussed in section. Fuselage profile lines must have a layer name as FUSL_k. The maximum number of points for each profile line is nf(k)

'5.

50. Fuselage cross-sections are defined in front view. A cross-section is a POLYLlNE ycr(i,m),zcr(i,m),wcr(i,m),i

=

1,9 (common block /cxfusc/). Foreach cross-~tion m with (m :5; 25) the corresponding fu-selage station xec(m) must be defined by avertical LINE-element drawn in side view. A POLYLlNE in a cross-section must have a layer name as FUSC_mm while the corresponding LINE-element must have a layer name as FUSX_mm.

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layer: CONS_nn xco(i,n)

yco(i,n)

Figure 2: Con trol surfaces geometry and positioning. ycr(i,m)

waist profile line (XY-projection) (k

=

4)

I_

xf(i,k) •

I

~~---~---xcr(m)

/ crowri profile line (k = 1)

keel profile line (k = 2)

Figure 11: Fuselage geometry definition. Eogioe type detinitioo aod positiooiog.

Similar to airfoil sections, engines are defined by a TEXT-element placed in top and side view. The TEXT -element defines the reference point location xnlo(n),ynlo(n,k) (common block Icxengll) of engine nacelle n with k = 1 for the top view and k = 2 for the side view, as shown in Fig)lTe 12 .. The maximum number of engine groups is n $; 3, i.e. aircraft configuration with up to 6 engines can be defined. The TEXT-elements may be rotated to define tilt angle ti(n) and toe angle torn) (com-monblock /cxeng2). The text string contains the engine designation engf(n) (common block /cxengfl). Note that an

ADAS/AutoCAD drawing only contains a reference to a particular engine type. The subprogram DXENGG is available

10 read engine nacelle geometry information from a specified DXF-file. The folJowing section explains how such a file should be created.

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I'

xnlo(n)

.

~---...,

to(n) > 0

I

yolo(nJ<)

Fe-u

_-J

fb

'---

k=1

'"

xnlo(n)

1

Ia,or.

ENG_,",

b

ynlo(n,k) _k=2

-/---re

34 - - .... -

,

_ti(n)_<₀

'-

I

-

- - - ---------~

Figure 12: Definition of engine type and location. Undercarriage geometry definition and positioning.

The undercarriage is represented by drawing the wheel outlines in top and side view for each undercarriage support strut assembly, as shown in Figure 14. In top view (k = I) the wheel outline is defined by a single POLYLINE Xlr(i,n),ytr(i,n),i

xtr(i,n)

, Iayer: GEAR_nnk

bS-~l

bh

'=2

X

~$_

= 1,3 (common block Icxucg2f). In side view (k = 2) a CIRCLE-element may be defined of which the centerpoint indicates the ztr(n) coordinate of the wheel assembly. The layer name is GEAR_nnk. The maximum number of wheels is nn $; 10. Lifting surface skin panels.

A skin panel n in lifting surface mis defined by a POLYLINE xskn(i,n,m),yskn(i,n,m),i = 1,4 (common block Icxskinf)

within the planform outline, as shown in Figure 16 .. The corresponding layer name is as SKIN_nnmm. The maximum

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xskn(i,n,m)

~

_ _ _ _ _ _ -'-yskn(i,n,m)

number of skin panels is n $ 5U. The subprograms DXLMSH and DXCKOS create a regular n x m grid for the skin panel. Fuselage skin panels.

Fuselage skin panel n is defined by drawing à POL YLINEs xss(i,n),zss(i,n),i = I,nss(n) (common block /cxfuss/) wim lin-ear segments in side view, as shown in Figure 17. The skin panel n (n ~ 25) left and right sides are defined by POLYLINE

~

layer: FUSS_nn

I

~--~-ri

---I I I zss(i~n) Z

I

: : I

I I I I I I I I I I "....-t---+-L.--+---I

n and n + 1 respectively. The layer name must be as FUSS_nn. The maximum number of points nss(n) ~ 5. The subpro-grams DXFMSH and DXCROS ereate a fuselage skin panel.

airf 0 /exwrf/

engf 0 /exengf/

file CH*(*) I Name of DXF-file with geometry data.

mes 0 /cxcons/ mir 0 /cxlsgl/ nf 0 /cxfusg/ nflp 0 /cxflps/ nled 0 /exleds/ np 0 /cxlsgl/ npc 0 /exnpax/ nps 0 /exnpax/ npx 0 /cxnpax/ nskn 0 /cxskinl

(41)

nslt 0 /exslts/ nspl 0 /exspls/ nss 0 /exfuss/ nsta 0 /exfusc/ ntr 0 /exueg2/ ntre 0 /cxtres/ nws 0 /exfdws/ to 0 /exeng2/ tw 0 /exairl/ wer 0 /exfusc/ wf 0 /exfusg/ xer 0 /exfusc/ xcs 0 /cxcons/ xdr 0 /cxdors/ xf 0 /exfusg/ xhld 0 /cxhlds/ xls 0 /exlsgl/ xnlo 0 /exengl/ xrf 0 /cxorgn/ xskn 0 /exskin/ xspl 0 /cxspls/ xss 0 /exfuss/ xst 0 /exseat/ xtr 0 /exueg2/ xtre 0 /extres/ xvv 0 /exview/ xws 0 /exfdws/ yer 0 /cxfusc/ yes 0 /cxeons/ ydr 0 /cxdors/ yf 0 /cxfusg/ yhld 0 /exhlds/ yls 0 /cxlsgl/ ynlo 0 /exengl/ yrf 0 /cxorgn/ yskn 0 /cxskin/ yspl 0 /cxspls/ ytr 0 /cxucg2/ ytre 0 /cxtres/ yws 0 /cxfdws/ yzv 0 /exview/ zer 0 /cxfusc/ zls 0 /cxlsgl/ zss 0 /cxfuss/ ztr 0 /cxucg2/ Subprograms called: dxline dxpoly fxgrea R*4 A-20

(42)

A-I3: DXDXFO: Open a DXF-file Syntax:

eaU dxdxfo (file) Purpose:

The subprogram DXDXFO opens a file for writing DXF-infonnation. IC file already exislS it will be overwritten. DXDXFO automatically writes the 4 standard header lines for the ENTITIES-section required in a DXF-file af ter open-ing ie

o

SECTION 2 ENTITIES

To close file use the subprogram DXDXFC.

(43)

A-14: DXELEM: Scan finite element model for coincident nodes Syntax:

caU dxelem (nbr .file) Purpose:

The subprogram DXELEM scans the intemal FE-model for coïncident nodes within a branch and resolves that condi-lion. Only those mesh areasj for which nb(j)

=

nbr are considered, i.e. coincident nodes between different branches are not affected. For each node i in mesh areaj with node number id(ij) the model is scanned for nodes which have equal node coordinali!sfx(id(ij»fy(id(ij»fz(id(ij» (within a cenain tolerance) but which have different node numbers. If sueh a node is found, the eorresponding node number is set to id(ij). Note that the duplicali! node is not removed but rather not used, this procedure may therefore result in a discontinuous node numbering.

fx Icxmeshl fy Icxmeshl fz I Icxmeshl id IlO fcxmesh/ nb I /cxmesh/ nbr I /cxmesh/ nd I /cxmesh/ ni I /cxmesh/ nj I Icxmesh/ A-22

(44)

A-IS: DXENGD: Read engine performance data from a file Syntax:

call dxengd (file)

Purpose:

The subprogram DXENGD reads engine perfonnance data from file. The first line contains the column headers in the order indicated. The following lines contains perfonnance data, i.e. thrust, fuel flow and mass flow as function of engine rating, Mach number and altitude, as a function. Engine rating, Mach number and altitude must be monotonie increasing, oherwise no restrictions are imposed.

Varia bIe Type 110 Description

engd 0 /cxengd/

erx 0 /cxengd/

file CH*(*) I Name of file with engine perfonnance data.

hhx 0 /cxengd/

na! 0 /cxengd/

nhx 0 /cxengd/

nmx 0 /cxengd/

(45)

A-16: DXENGG: Read engine geometry from a DXF-file

Syntax:

call dxengg (file,n)

Purpose:

The subprogram DXENGG reads nacelle geometry information for engine n from DXF-file. The geometrie definition of an engine nacelle is basically similar to !hat of the fuselage. DXENGG scans the DXF-file and reads the entities shown in Figure. 1. POLYLINE-entities placed in Iayer NACLjc represent profile lines xn(i.k.n).yn(i.k.n).wn(i.k.n) with k =1

~ e::l~W~'="~~4)

(0.0)

layer: NACX_mm

crown profile Jine (k

=

1)

(O.o)II--K:-1----+-+-.h~

=

3)

keel profile line Ck

=

2)

for the crown !ine, k

=

2 for the keelline, k

=

3 for the waist line projection in side view and k

=

4 for the waist Jine pro-jection in top view. The numberofpoints in eaeh profile line is returned in nn(k,n). in xn(i.k.n).yn(i.k.n).wn(i.k.n).i

=

1.nn(k.n). The eross-section lines are stored in xee(ij.k.n).zee(ij.k.n).wee(ij.k.n).i = 1,5 with} < nee. k = 1 for the upper section and k = 2 for the lower seetion.

file CH*(*) Name of DXF-file with naeelle geometry data.

n 1*4 1 Engine number. nee 0 /exenge/ on 0 /exnaeg/ nnr 0 /exenge/ wee 0 /exenge/ wn 0 /exnaeg/ xee 0 /exenge/ xn 0 /exnaeg/ yee 0 /exenge/ yn 0 /exnaeg/ zee 0 /exenge/ A-24

(46)

A-I7: DXENGP: Write engine geometry to a DXF-file Syntax:

caIl dxengp (n) Purpose:

The subprogram DXENGP writes nacelle geometry information of engine n to the DXF-file open on unit 10. i.e. the file

must already be open at the time DXENGP is called. DXENGP places the engine name engf(n) in top and side view

with layer ENG_nI and ENG_n2 respectively. The profile lines are drawn with layer O.

engf /cxengf/ n 1*4 Engine number. on /cxnacg/ wo /cxnacg/ xn /cxnacg/ xnlo /cxengl/ xrf /cxorgn/ yn Icxnacg/ ynlo /cxengl/ yrf /cxorgn/

(47)

A-IS: DXFEMA: Write vector-coded FE-model to a DXF -file Syntax:

call dxfema (scl ,sc2) Purpose:

The subprogram DXFEMA writes instanees (INSERTs) of the BLOCK entity named ARROW to the OXF-file open on unit 10. The OXF-file must be opened before DXFEMA is called. e.g. using the subprogram DXDXFO. DXFEMA essentially creates a vector field by orienting 30 arrow symbols according to a specified vector solution xvU). yvUJ and zv(jJ and placing them at the centroid of the corresponding 4-node element j. The vector is scaled as a function of the

solution scalar SCü

J.

as follows:

(sc(j) -scmin) (sc2-scI)

scale = dl x (sc 1

+

. )

scmax - scmm

where scmin and scmax are the minimum and maximum value of sc respectively. Because the arrow symbols are drawn

in world coordinates the maximum average diagonallength dl of all elements in the model is used as a sealing reference.

It may be necessary fust to define the BLOCK entity ARROW by inserting the file /voVadas/arrow.dwg before applying

OXFIN on the OXF-file.

Variabie iJ i2 i3 i4 ne scl sc2 xe xv ye yv ze zv Type R*4 R*4 110 /cxelem/ /cxelem/ /cxelem/ /cxelem/ /cxelem/ Description

Minimum scale factor.

Maximum scale factor.

/cxelem/ /cxsolv/ /cxelem/ /cxsolv/ /cxelem/ /cxsolv/ A-26

(48)

A-19: DXFEMC: Read finite element model geometry description from a file Syntax:

caII dxfemc (file)

Purpose:

The subprogram DXFEMC reads a FE-model geometry description from afile. The required data format is similar to

that produced by the subprogram DXELEM, except that a solutiOll scalar andlor vector may be associated with each

ele-ment for post-processing, for example:

BRANCH = 1 NODES 1 19192.699 0.000 3082.9001 2 19719.102 0.000 3020.8899 3 20242.398 0.000 2959.3700 4 20458.600 0.000 2898.8999 5 18710.381 0.000 2742.4600 6 19266.420 0.000 2679.2500 7 19821.629 0.000 2616.5900 8 20051.170 0.000 2555.1499 9 18172.539 0.000 2355.4700 10 18764.520 0.000 2294.4600 11 19357.770 0.000 2233.9600 12 19603.549 0.000 2173.3540 13 17600.180 0.000 1934.6300 14 18228.209 0.000 1874.8900 15 18859.910 0.000 1815.6600 16 19121.861 0.000 1756.3401 17 20882.600 -184.022 3275.8601 18 20878.799 -129.707 3246.5000 19 20882.400 0.000 3276.3601 20 20879.299 0.000 3246.8999 21 19692.801 -184.265 3504.9800 22 19684.900 -158.966 3424.9399 23 19692.701 0.000 3504.9500 24 19684.500 0.000 3424.8799 25 20089.100 -183.374 3379.7700 ELEMENTS 556 17 18 20 19 10101 135.53 557 21 22 24 23 10101 5.08 558 21 22 24 23 10101 5.08 559 21 25 27 22 10101 102.87 560 25 26 28 27 10101 542.71 561 26 17 18 28 10101 192.61 562 17 18 20 19 10101 135.53 563 21 22 24 23 10101 5.08 564 21 22 24 23 10101 5.08 565 21 25 27 22 10101 102.87 566 25 26 28 27 10101 542.71 567 26 17 18 28 10101 192.61 568 29 30 34 33 10101

3.44

569 30 31 35 34 10101 2.24 570 31 32 36 35 10101 3.72

Aircraft design and analysis systems (ADAC)

1°010)1

Aircraft Design and Analysis System

(ADAS)

1111I1111111

Series 02: Flight Mechanics

02

Aircraft Design and AnalysisSystem

(ADAS)

C.

Bill/F. van Dalen/A. Rothwell

Delft University Pre ss / 1997

2392

331

7

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Part 1

Aircraft Design and

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Table of Contents

t::=~

=

==:1

l