MSC 1989 World Users' Conference Proceedings

The conference proceedings for the 1989 World Users' Conference are now available on-line in Adobe Acrobat PDF format. (The Adobe Acrobat Reader software is available for free download from Adobe's web site at www.adobe.com.) When printed, these PDF files will produce a better quality image than the one shown on your computer screen.

OVERVIEW OF MSC'S PLANS AND PROJECTS (Acrobat 430K) #0189, 4 pgs.
Joseph F. Gloudeman, President and Chief Executive Officer--The MacNeal-Schwendler Corporation

ABSTRACT: A most important piece of news for this 1989 World Users Conference is that MSC has delivered production versions of software that we have promised you in the past. I will give you a broad overview to serve as an introduction to the following presentation and share with you the strategic thinking behind our corporate thrusts.

STATUS OF MSC/NASTRAN #0289 (No Text Available)
M.A. Gockel, VP, Technical Operations--The MacNeal-Schwendler Corporation, Los Angeles, California

ABSTRACT: A brief history of the evolution of Version 66 of MSC/NASTRAN is given. Each enhancement is discussed, including the new executive system and the new design optimization capability. Computer and operating system types which MSC supports are listed. Plans for future versions of MSC/NASTRAN in the areas of integration with other MSC products, enhancements in basic capabilities, and porting to new computer architectures are discussed.

To obtain the text, please contact the author directly:
Mr. M.A. Gockel
The MacNeal-Schwendler Corporation
815 Colorado Blvd.
Los Angeles, CA 90041-1777

MSC ELECTROMAGNETIC PRODUCTS #0389 (No Text Available)
Dr. Robert Bodine, Director, E/EAD--The MacNeal-Schwendler Corporation, Milwaukee, Wisconsin

ABSTRACT: The status of current electromagnetic analysis capabilities will be reviewed with respect to functional capabilities and some types of applications. The thrust of new development efforts will be summarized, including comments on some prospective applications. The presentation will begin with a brief perspective on the relation of electromagnetism and theoretical mechanics.

To obtain the text, please contact the author directly:
Dr. Robert Bodine
The MacNeal-Shwendler Corporation
Engineering/Electromagnetic Applications
9076 N. Deerbrook Trail
Milwaukee, WI 53223

MSC/XL #0489 (No Text Available)
Don McLean, VP, Advanced Projects--The MacNeal-Schwendler Corporation, Los Angeles, California

ABSTRACT: One of the major tools from MSC for the 90's will be MSC/XL. We recently announced this product as a pre- and postprocessor for MSC/NASTRAN. The future for this tool is to integrate the analysis packages from MSC--MSC/NASTRAN, MSC/DYNA, MSC/EMAS, and others with a common, easy-to-use, interactive graphical tool.

To obtain the text, please contact the author directly:
Dr. Don McLean
The MacNeal-Schwendler Corporation
815 Colorado Blvd.
Los Angeles, CA 90041-1777

MSC/DYNA AND EXPLICIT TRANSIENT DYNAMIC ANALYSES #0589 (No Text Available)
Samuel W. Key, Chen S. Tsay--The MacNeal-Schwendler Corporation, Los Angeles, California

ABSTRACT: MSC/DYNA is a computer program designed for the analysis of highly nonlinear transient dynamic events in three dimensions. MSC/DYNA is a proprietary adaptation of DYNA3D, developed by Dr. John Hallquist of the Lawrence Livermore National Laboratory. MSC/DYNA is based on the December 1988 version of DYNA3D. Dr. Hallquist has provided technical help to MSC throughout the project and has been instrumental in its success.

To obtain the text, please contact the author directly:
Dr. Samuel Key
The MacNeal-Schwendler Corporation
815 Colorado Blvd.
Los Angeles, CA 90041-1777

RECENT ELEMENT DEVELOPMENTS (Acrobat 842K) #0689, 16 pgs.
Richard H. MacNeal, Chairman--The MacNeal-Schwendler Corporation, Los Angeles, California

ABSTRACT: Recent developments with regard to the MSC/NASTRAN elements include a new four-noded membrane element, which is delivered with Version 66, and a companion three-node membrane element which is in the breadboard testing phase. In addition, the entire 2D and 3D element library is under review with an eye toward the elimination of such design deficiencies as locking and failure to pass the patch test by the incorporation of recent theoretical advances.

The paper summarizes these recent advances and indicates how they have been applied to the design of the QUAD4R and TRIA3R membrane elements. Test results are presented which show the improvement in accuracy of the new elements over the older QUAD4 and TRIA3 elements.

MSC/XL #0789 (No Text Available)
Paul A. Zelenski--The MacNeal-Schwendler Corporation, Los Angeles, California

To obtain the text, please contact the author directly:
Paul A. Zelenski
The MacNeal-Schwendler Corporation
815 Colorado Blvd.
Los Angeles, CA 90041-1777

USER EXPERIENCES WITH MSC/XL #0889 (No Text Available)
NKF Engineering, Inc., Reston, Virginia

To obtain the text, please contact the author directly:
NKF Engineering, Inc.
1220 Sunrise Valley Dr.
Reston, VA 22091

CAE DIALOGS FOR MSC/NASTRAN (Acrobat 1382K) #0989, 16 pgs.
Darryl G. Chong, Salvatore M. Vicari--IBM Corporation, San Jose, California

ABSTRACT: Finite-element analysis is becoming increasingly widespread in engineering design as general-purpose programs have become more available. However, further improvements in ease-of-use are still needed for many popular finite-element analysis codes. This paper describes the CAE Dialog environment for MSC/NASTRAN developed for the IBM-MVS host at the IBM General Products Division in San Jose, California. The interactive dialogs use the ISPF/PDF Program Product to enable the analyst to communicate to MSC/NASTRAN through a set of user-friendly panels, or screens, displayed to the computer terminal. The dialogs illustrate how the required tasks can be simplified for programs that require both a formatted input file and job stream control for batch job submission. To create the input data stream, selections from a library of data macros are interactively merged into the input file by menu selection. This library is customized to solution requirements of the local user community. Dialog panels are used to select job features and define input-output files for MSC/NASTRAN execution, preprocessing, and postprocessing tasks. The selections are stored in a job profile, from which the job stream is automatically created. By making MSC/NASTRAN easier to set up and execute, less prior computer knowledge is required. Application utilities are provided for printing, plotting, program interfaces, file management, job status, and output review. An on-line news facility and user forum provide for convenient dissemination of application news and encourages communication among users remotely located from one another. By creating similar sets of ISPF dialogs for related CAE analysis software, a fully integrated environment is presented to the engineering analyst.

FINITE ELEMENT MESH GENERATION IN THE FRAMEWORK OF AN EXPERT SYSTEM (PRE-POST PROGRAM "SCOPE"- INTERFACE TO MSC/NASTRAN) (Acrobat 1071K) #1089, 16 pgs.
Koichi Mikami, Yoshio Iwahashi, Osamu Murakawa, Tsuneo Sakato--Sumitomo Heavy Industries. Ltd., Japan

ABSTRACT: This paper describes an expert system to automatically generate finite elements which is a subsystem of finite element pre-processing system named "SCOPE".

In SCOPE, the geometric shape of analysis model is represented as a collection of bicubic parametric surface patches and finite elements are generated through the mapping of mesh divisions in the parametric space. The task of selecting the number of division for each surface patch is carried out by an expert system. The problem is formulated as multiobjective optimization with respect to the total number of elements, element aspect ratio and element size. The actual optimization process is implemented by using the concept of the Generalized Problem Solving as applied to a robot planning.

The effectiveness of the approach is demonstrated by several examples and the potential expansion of the method is discussed.

INDIVIDUAL MODAL ACCELERATIONS AS THE RESULT OF A SHOCK RESPONSE SPECTRA INPUT TO A COMPLEX STRUCTURE (Acrobat 663K) #1189, 11 pgs.
Fred Cutting--Honeywell Avionics Division, Clearwater, Florida

ABSTRACT: An MSC/NASTRAN finite element model was developed and dynamic analysis was accomplished for a ring laser gyro guidance system designed to function on a steerable reentry warhead. This model contains approximately 1200 nodes, 6500 dof, using 44 ELAS2, 1017 QUADA, 677 BAR, 8 HEXA and 4 TRIA3 elements. Generalized dynamic reduction was used with the modified Givens technique to obtain 102 eigenvalues from DC to 3 KHz. Sixty-three (63) eigenvectors were calculated.

Ring laser gyros (RLG) are mechanically dithered to avoid laser lock-in. These gyros are dithered at 600 to 750 Hz with low power peizo-electric devices. It is important that no chassis resonance in this frequency range couple into the gyro dither frequency. Therefore, the chassis must be very stiff.

The RLG is sensitive to acceleration as a function of frequency because of internal resonances with high transmissibilities. For this reason, a unique DMAP "alter 1050" was developed to provide the resultant accelerations for each mode shape for the specified shock response spectra input. (SOL63)

PROPELLER/NACELLE WHIRL FLUTTER ADDITION TO MSC/NASTRAN (Acrobat 1806K) #1289, 29 pgs.
William P. Rodden, Ted L. Rose--The Macneal-Schwendler Corporation, Los Angeles, California

ABSTRACT: A preprocessor has been developed to include propeller/nacelle aerodynamic and gyroscopic forces in MSC/NASTRAN flutter analysis with SOL 75. The propeller is assumed to be rigid. The effects of wing downwash on the propeller forces are also included. The equations of motion are presented along with two example problems. The first example is a simple two degree of freedom propeller and correlations with wind tunnel data are shown. The second example is the cantilevered BAH wing with a nacelle, propeller and rotor added. The whirl flutter speed is shown along with the effects of the propeller/nacelle on the wing flutter and divergence characteristics. The effects of the wing downwash are also shown. The inclusion of propeller wake effects on the wing loads by using correction factors is discussed.

ROTOR DYNAMIC ANALYSIS WITH MSC/NASTRAN VIA THE IMPORTANT MODES METHOD (Acrobat 1028K) #1389, 14 pgs.
R.A. Barnes, R. Schmidt, H.C. Adrick--GE Aircraft Engines, Cincinnati, Ohio

ABSTRACT: This paper describes an MSC/NASTRAN solution procedure by which the problem size of a free or forced complex modes rotor dynamics analysis may be substantially reduced with minimal loss of accuracy. Strain and kinetic energies in the system normal modes are calculated for user-designated groups of elements with the engine. Then, the "importance" of each mode is assessed based on whether or not the elements in the rotors contain a preselected small percentage of energy relative to the entire system energy content. The complex eigenvalue solutions are then formulated containing only these "important" normal modes. It is predicted that these modes which are judged to be active based on energy content will be affected by gyroscopic moments and rotor unbalance loads.

DMAP alters were written for inclusion in Solutions 63, 70, and 71. The DMAP alters for Solution 63 direct that mass, eigenvalue, eigenvector and strain energy data be output into binary files for subsequent processing. The alters for Solution 70 and 71 use DMI entries in the bulk data to choose which of the normal modes are to be used in the complex solution and to direct that the above data be output for further processing. Post-processing programs were created to calculate the desired strain an kinetic energies, to tabulate the energies by engine component, and to prepare data for subsequent graphical presentation.

A PRACTICAL SOLUTION TO MODE CROSSING PROBLEM IN CONTINUOUS ITERATIVE PROCEDURE #1489 (no text available)
Tienko Ting--University of Bridgeport, Bridgeport, Connecticut. Timothy L.C. Chen, William Twomey--Sikorsky Aircraft, Stratford, Connecticut

ABSTRACT: In a continuous iterative procedure, which requires a sequence of normal mode reanalyses, the mode ordering may change, resulting in an inconsistent correspondence between the results of two consecutive analyses in terms of mode numbers. This paper suggests a practical way to accommodate the problem and will demonstrate a method by using a numerical problem involving modal correlation of a large-scale structure. The Modal Assurance Criterion (MAC) is used to determine the correct correspondence between the mode numbers and mode shapes of successive runs. This method eliminates complex mathematical treatments and requires only two consecutive sets of eigenvectors from the corresponding analysis results, and is a practical and economical way of handling the mode crossing problem.

To obtain the text, please contact the author directly:
Tienko Ting
University of Bridgeport
221 University Ave.
Bridgeport, CT 06601

or
Timothy L.C. Chen or William Twomey
Sikorsky Aircraft
6900 Main Street
Stratford, CT 06601

NON-LINEAR DEFLECTION ANALYSIS OF A SPACE SUIT WAIST BEARING (Acrobat 1547K) #1589, 22 pgs.
J.C. Lambert, W.M. Merritt--United Technologies Corporation, Windsor Locks, Connecticut

ABSTRACT: A deflection analysis of a space suit waist bearing has been conducted using MSC/NASTRAN. The space suit waist bearing is a ball bearing, about 15.5 inches in diameter, subject to axial point loading due to suit pressure and man loads. Using CGAP elements and SOL66, the nonlinear stiffening effects of this bearing were considered. Evaluation of these non-linear stiffening effects is necessary for proper calculation of radial and axial deflections which are important in the design of space suit seals.

This paper outlines the complexities of the space suit waist bearing and the analysis technique used to investigate its behavior. It also highlights the results of the analysis and demonstrates, under various load conditions, how changes in ball contact angle affect overall bearing stiffness. This analysis technique enables designers to understand the behavioral characteristics of deflection sensitive bearings without costly prototype development.

A NON-LINEAR FINITE ELEMENT APPROACH TO GEAR TOOTH LOAD SHARING PROBLEM (Acrobat 119K) #1689
Raymond J. Drago, Ravi N. Margasahayam--BOEING Helicopters, Philadelphia, Pennsylvania

ABSTRACT: Increased emphasis on lightweight, high power-to-weight ratio requirements in modern day helicopters, has led to improved materials and lubricants, as well as advances in gear design and manufacturing technology.

In the area of gear design, increasing load-carrying capability has been achieved by going from low to high contact gears. Here, gear mesh and the pairs of teeth in contact alternates from one for low contact ratio gears, to two or three for high contact ratio gears. By distributing the load among more than one tooth, and with due consideration to pitting and scoring, one can increase the load carrying capacity with little or no weight penalty in most instances.

Manufacturing tolerances, tooth errors, profile modifications, and system misalignment will significantly influence the proper distribution of load among the teeth in contact. Perfect load sharing, of course, can only occur with perfect accuracy and tooth modification. Lack of load sharing, implies that one has to modify the geometry factor (which evaluates the shape of the tooth, the amount of load sharing between teeth, and root stress concentration effects, used in gear strength computations.

Accurate calculation of load sharing among meshing tooth pairs, especially for lightweight, thin-rimmed gears, is one of the main problems facing gear designers. The present paper formulates the gear tooth load sharing problem into a static, geometrically non-linear model, in an attempt to predict the load carrying capability including the effect of load induced gear and rim deflections.

Distribution of load across the gear face, as well as among the gear teeth (Load Sharing), were computed using Gap elements and Sol 66 of MSC/NASTRAN.

A PREVIEW OF MSC/EMAS #1789 (No Text Available, oral presentation only)
B.E. MacNeal, N.J. Lambert--The MacNeal-Schwendler Corporation, Los Angeles, California

RADIATION HEAT EXCHANGE IN A HIGH TEMPERATURE INDUCTION FURNACE
#1889 (No Text Available)
C.C. Chao, D.P. Hill, J.P. Kalejs, and S. Rajendran--Mobil Solar Energy Corporation, Billelica, Massachussetts. Vern Overbye--The MacNeal-Schwendler Corporation, Milwaukee, Wisconsin

ABSTRACT: A high temperature (2000 C) induction furnace used to grow hollow silicon polygons is modeled as an axisymmetric structure. MSC/MAGNETIC is used to predict induced power loss in furnace materials and melt due to a surrounding high frequency coil. A radiation matrix is constructed by subdividing the furnace cavities into several radiation zones and using the MSC/NASTRAN VIEW module to obtain view factors within each zone. Nonlinear Steady State thermal analysis (SOL 74) is then performed with temperature dependent material properties to predict temperature distribution, especially in critical solidification zone. Color graphics (including MSC/GRASP) display temperature within the furnace.

Experience with REV-option surface elements in the VIEW module (including manual balancing of RADMIX columns) is summarized. Suggestions are made for improvement of radiation thermal analysis in future MSC finite element programs (previewed at the 1988 World Users Conference).

To obtain the text, please contact the author directly:
Vern Overbye
The MacNeal-Schwendler Corporation
Engineering/Electromagnetic Applications Dept.
9076 N. Deerbrook Trail
Milwaukee, WI 53223

FINITE ELEMENT ANALYSIS APPLIED TO AVIONICS MOUNT (Acrobat 2815K) #1989, 24 pgs.
James D. Sampica--Rockwell International Corporation, Cedar Rapids, Iowa

ABSTRACT: A major concern in the commercial avionics industry is how equipment that is placed throughout an aircraft, reacts during inflight conditions. This equipment includes panel mounted instrumentation, remote rack mounted black boxes, and antennas that are mounted on the outside of an aircraft. All of the equipment is susceptible to a variety of conditions: temperature, humidity, salt, vibration, rain, shock, and altitude are just a few of the environmental concerns to an avionics engineer in designing a product.

APPLICATION OF MSC/NASTRAN SENSITIVITY ANALYSIS AT NISSAN MOTOR COMPANY (Acrobat 758K) #2089, 8 pgs.
Kazuo Nagabuchi, Ichiro Hagiwara, Akira Arai--Nissan Motor Company, Ltd., Yokosuka, Japan

ABSTRACT: A pre-post processing system for MSC/NASTRAN sensitivity analysis has been developed. The effectiveness of the sensitivity analysis has been well recognized. However it is difficult for many designers to use it. This system creates MSC/NASTRAN design sensitivity data. With this system, the analytical results can be estimated easily. Some application examples are presented in this paper.

APPLICATION OF DESIGN SENSITIVITY ANALYSIS TO IMPROVE CORRELATIONS BETWEEN ANALYTICAL AND TEXT MODES (Acrobat 1582K) #2189, 18 pgs.
John M.W. Lee--Hughes Aircraft Company, El Segundo, California. Grant R. Parker--The MacNeal-Schwendler Corporation, Los Angeles, California

ABSTRACT: A procedure is presented for obtaining better correlation between analytical and test modes. MSC/NASTRAN Modal Design Sensitivity Analysis was employed for this application. The derivatives of the constraints, in this case the eigenvalues, with respect to the design variables (such as cross sectional properties) indicate the significances each design variable has on all the modes of interest. This procedure eliminates the necessities for performing costly multiple trial and error mode runs. The Bell AH1G model was used for this particular study. This work was performed during the fourth quarter of 1987 under a Bell Helicopter Textron Inc. contract study as part of the NASA BAMVIBS program. The results were presented at NASA Langley Research Center in May of 1988 under contract NAS1-17496. This task represented a six man-week effort. In addition, design sensitivity can be an excellent tool for providing quick inputs for design modifications during flight test stages of typical aircraft programs.

DESIGN SENSITIVITY FOR MODAL ANALYSIS #2289 (No Text Available)
Gopal K. Nagendra, David N. Herting--The MacNeal-Schwendler Corporation, Los Angeles, California

ABSTRACT: For calculating Sensitivity derivatives in Modal formations (Modal Frequency Response, Model Transient Response), the derivatives of eigenvector are usually required. For large structures with many modes the calculation of eigenvector derivatives is a fairly expensive operation. A new method is presented which no longer requires the calculation of eigenvector derivatives, resulting in substantial efficiency improvements. The important response terms are displacements, stresses, forces, etc. while eigenvector derivatives are only an intermediate step. Introduction of intermediate variables using the mode shapes as Rayleigh-Ritz shape functions results in simplified equations for calculating the Sensitivity derivatives. Test problems illustrate the improved efficiency and minimal loss in accuracy.

To obtain the text, please contact the author directly:
Gopal K. Nagendra or David N. Herting
The MacNeal-Schwendler Corporation
815 Colorado Blvd.
Los Angeles, CA 90041-1777

GRID SENSITIVITY ANALYSIS USING MSC/NASTRAN (Acrobat 1663K) #2389, 22 pgs.
Gopichand Somayajula--Ford Motor Company, Dearborn, Michigan. James E. Bernard--Iowa State University, Ames, Iowa

ABSTRACT: This paper presents a method to compute the sensitivities of displacements and natural frequencies to the changes in grid locations. The sensitivities are computed within MSC/NASTRAN using the semi-analytical method via a DMAP program. New software was developed to assist in the selection of design variables, and plot the spatial variation of the sensitivities on the finite element (FE) model using PDA/PATRAN. Two example problems demonstrate the technique.

A FINITE ELEMENT TECHNIQUE FOR TAPE-HEAD INTERACTION PROBLEMS IN HIGH SPEED RECORDING: THE STEADY-STATE CLAUSE (Acrobat 773K) #2489, 14 pgs.
Arturo O. Cifuentes, Timothy L. Bock, Robert N. Coppolino--The MacNeal-Schwendler Corporation, Los Angeles, California

ABSTRACT: This paper presents a finite element technique to model the steady-state response of a flexible tape during high-speed recording. The tape is modeled as a flexible plate, including geometric nonlinearities due to large deflections. The air film pressure field is described using a modified version of Reynolds equation for compressible fluids. A new nonlinear finite element that couples both air-film and tape mechanics is described in detail. This element, which has been incorporated into a standard finite element code (MSC/NASTRAN), allows one to determine the pressure field and the air-film thickness due to tape-head interaction. An example demonstrates the usefulness of this technique.

APPLICATION OF FLANIGAN'S MODE ACCELERATION IN MSC/NASTRAN VERSION 66 (Acrobat 1223K) #2589, 16 pgs.
Thoms G. Butler--Butler Analyses, Baltimore, Maryland. John C. Muskivitch--The MacNeal-Schwendler Corporation, Rockville, Maryland

ABSTRACT: Twice before Chris Flanigan has briefed our MSC finite element community on an alternate approach to improve transient solutions using the modal method. Not until his 1988 paper did he present his material in so convincing a fashion that everyone was forced to sit up and take notice. What made his approach so imperative was the situation that the analyst faces when solving his modal transient problem using superelements.

EIGENVALUE REANALYSIS USING SUBSPACE ITERATION TECHNIQUES (Acrobat 1069K) #2689, 16 pgs.
Gopichand Somayajula, Joseph Stout, John Tucker--Ford Motor Company, Dearborn, Michigan

ABSTRACT: During the process of designing dynamic elastic systems, it is often necessary to determine the effect of various design changes on the system dynamic characteristics, e.g., natural frequencies and mode shape. Reanalysis techniques analyze changes with less computational effort. One such technique is a reduced basis method. This method is limited to design changes that do not significantly alter the resultant mode shapes. The proposed method, subspace iteration, allows for large changes in the mode shapes. This technique iterates the baseline solution until certain convergence criteria are met and is executed inside MSC/NASTRAN using a DMAP alter with user-specified parameters. An example demonstrates the accuracy and computational savings of the method.

THE COMPUTER AIDED DESIGN ANALYSIS AND STRUCTURAL OPTIMIZATION OF ENGINE ACCESSORY COMPONENTS (Acrobat 1274K) #2789, 10 pgs.
R.I. DeVries, H.V. Radziwon, P. Aghssa--Ford Motor Company, Dearborn, Michigan

ABSTRACT: This paper describes the integration of computer graphics, finite element analysis including design sensitivity analysis, and structural optimization technology to automate the design analysis and design optimization of engine accessory components. By use of MSC/NASTRAN's design sensitivity analysis and structural optimization methodology, the design of vehicle components is facilitated to achieve both design improvement and a significant increase in engineering efficiency.

The application of this technology to two typical engine accessory brackets for minimum weight design subject to constraints on stresses due to applied loads as well as natural frequencies is described.

SHAPE OPTIMIZATION WITH MSC/NASTRAN #2889 (No Text Available)
M. Chargin -- NASA Ames Research Center, Moffett Field, CA
I. Raasch and R. Brun -- BMW, Munchen, West Germany
D. Deuermeyer -- Cray Research Inc., Mendota Heights, Minnesota

ABSTRACT: Structural optimization is almost as old as the Finite Element Model (FEM). Whereas FEM found its way to real life applications very quickly, structural optimization remained a topic of interest in the research community for many years. However, there have been a number of attempts recently to develop general purpose program systems for property optimization. For shape optimization, there is no general purpose code currently available that can solve realistic problems. This paper will describe a method of calculating shape sensitivities within MSC/NASTRAN, in a simple matter, without resort to external programs. Once the shape sensitivities are obtained, the shape optimization process can proceed in a manner similar to property optimization.
The key concept is the use of natural design variables to define the shape changes in a given structure. The design variables are the magnitudes of enforced displacements applied to the structure. The displacements produced by these variables are added to the initial shape to obtain a new shape. This approach can be computationally intensive and since one shape variable is independent of another, multiple CPU's can be used to significantly reduce the solution time.
Two examples are solved to demonstrate the capability of these techniques. The first is a cantilever beam with holes loaded by a point load at the free end. The shape of the holes as well as the thickness of the beam are selected as the design variables. The second example is the shape optimization of a BMW engine connecting rod subjected to several different loading and boundary conditions.

To obtain the text, please contact the author directly at the following address:
M. Chargin
NASA Ames Research Center
Moffett Field, CA 94035

ON THE SHAPE OPTIMIZATION OF LARGE STRUCTURES (Acrobat 381K) #2989, 7 pgs.
Dr. Dirschmid -- AUDI AG, Ingolstadt, West Germany

ABSTRACT: A method is presented which achieves an optimized shape of a structure with very many degrees of freedom, by a global consideration and by neglecting local effects.

SHAPE SENSITIVITY DERIVATIVES: FINITE DIFFERENCES VERSUS ANALYTICAL APPROACHES #3089 (No Text Available)
Y.K. Shyy and C. Fleury -- University of California, Los Angeles

ABSTRACT: Recent published results indicate that the semi-analytical aproach to sensitivity analysis is subject to serious accuracy problems, particularly when shape design variable are involved. In this paper, the three most commonly used sensitivity analysis methods are compared on the basis of their accuracy, as well as their efficiency: overall finite differences, semi-analytical, and analytical methods. The sources of errors in these three methods are clearly identified and explained. The analytical approach is shown to be the most efficient, accurate, and reliable method. Its only drawback is that it requires a significant effort in implementation. The analytical method is then extended to calculate second order sensitivity derivatives in the context of the p-version FEM. Some classical shape optimization problems are solved by using conventional optimizers, based only on first order sensitivity derivatives. Next, various second order optimization strategies are experimented in order to improve convergence. Finally, a very effective shape optimization procedure, which fully utilizes the advantages of the p-version FEM, is derived from this study.

To obtain the text, please contact the author directly at the following address:
Y.K. Shyy or C. Fleury
Mechanical, Aerospace and Nuclear Engineering Dept.
University of California, Los Angeles
Los Angeles, CA 90024

SHAPE AND MESH OPTIMIZATION USING GEOMETRIC MODELING METHODS
#3189 (No Text Available)
D. Liefooghe and C. Fleury -- University of California, Los Angeles

ABSTRACT: In shape optimal design problems it is essential to control the validity of the finite element mesh whenever the boundaries of the domain are modified. The ultimate goal is to optimize simultaneously the external shape as well as the internal mesh density, so that the FEM results remain sufficiently accurate to drive the optimum shape toward a realistic and meaningful design.
The geometric model that we have devised is characterized by two different sets of design variables. The "shape variables" define the positions of control nodes along specified move directions. They govern the geometry of the boundaries as done in our previous research projects. An additional set of "mesh variables", running along the boundary curves, has been introduced, which controls the density of the finite element mesh. We currently can handle effectively geometric constraints on the internal angle in each element, as well as more complicated constraints on the error in the FEM stress results.
Turning to the optimization strategy, we have initially adopted a simple sequential approach, where a shape optimization is first accomplished for a given set of mesh variables, followed by a mesh optimization for a given set of shape variables. Next an integrated approach has been implemented, where shape and mesh variables are treated simultaneously. The paper will provide a comparison between these two approaches.
Although the current implementation is restricted to two-dimensional elastic structures meshed with isoparametric eight-node elements, the same concepts could clearly be employed to deal with more complicated design problems, such as those routinely analyzed by MSC/NASTRAN.

To obtain the text, please contact the author directly at the following address:
D. Liefooghe or C. Fleury
Mechanical, Aerospace and Nuclear Engineering Dept.
University of California, Los Angeles
Los Angeles, CA 90024

EVALUATING STRESSES IN ADHESIVE BOND LINES (Acrobat 855K) #3289, 13 pgs.
Alson E. Hatheway -- Alson E. Hatheway Inc., Pasadena, California

ABSTRACT: Adhesive bond lines are difficult to model in structural analysis because their small dimensions, typically .003 to .010 inches thickness, are so small with respect to the dimensions of a normal structural model that the analyst becomes trapped between computational accuracy and problem size. This paper presents a technique used recently to evaluate the adhesive bonded joints in an aluminum sheet metal structure.
The solution includes an analysis of the important causes of high bond stresses and detail modeling of typical bond line constructions. The paper includes guidelines the author found useful to avoid computational problems in this kind of analysis.

A NEW CADAM CAE WORKSTATION PRODUCT (Acrobat 350K) #3389, 6 pgs.
Henry J. Schultz -- CADAM, Inc., Burbank, California

ABSTRACT: CADAM, INC, a leader in the CAD/CAM/CAE market place for over 20 years, is now positioned to increase its strong presence with the development of a new full featured workstation CAE product. At the core of this new product will be direct support of MSC NASTRAN including the latest release. As this new product is not a derivative of the old CADAM 3D Mesh product, but a completely new development, it will be able to take advantage of the latest hardware and software support. This paper provides a comprehensive overview of this product.

GENERATING STIFFNESS MATRICES, GENERAL ELEMENT INPUT AND ROTATED MATRICES USING MSC/NASTRAN (No Text Available)#3489
P.F. Martin -- MIT Lincoln Laboratories, Lexington, Massachussetts

COMPUTATION OF THE EIGEN-FREQUENCIES OF ACOUSTIC CAVITIES: A NEW PENALTY METHOD (Acrobat 570K) #3689, 12 pgs.
Arturo Cifuentes and Robert Coppolino -- MSC, Los Angeles, CA

ABSTRACT: A new penalty method for determining the natural frequencies and normal modes of acoustic cavities is presented. The acoustic medium is described in terms of the displacement field. A new easy-to-implement penalty function method is employed to enforce the irrotationality condition. This new method has significant advantages when compared to classical penalty function methods since it is more stable with respect to the penalty parameter.

INTEGRATING FINITE ELEMENT ANALYSIS WITH QUASI-STATIC LOADINGS FROM A LARGE DISPLACEMENT DYNAMIC ANALYSIS (Acrobat 1173K) #3789, 10 pgs.
Patrick Ryan Turner -- Schlumberger Technologies, Ann Arbor, Michigan

ABSTRACT: A method for capturing mechanical loads (both joint and inertial) from results produced by a large-displacement elasto-dynamic analysis program and directly applying them to a finite element model is presented. This procedure allows the analyst to perform a quasi-static equilibrium analysis without regard to actual boundary conditions. Errors are minimized and productivity increased by automating the transfer of "complete" and "consistent" date between different analysis types. In fact, total design analysis accuracy is increased over standard practices because approximation in the transfer of load information is eliminated.
The importance of model consistency required between the two analysis types, and how to assure it, is presented. The method for transferring the mechanical and inertial loads was found to be independent of the particular element type used in the finite element analysis. The theory required to understand the process will be briefly outlined along with suggestions for checking the accuracy/consistency between the ADAMS model and the FE model. The focus of this paper is a process that dramatically reduced the work needed to "accurately" model the loading conditions of a mechanical part undergoing dynamic motion.

MSC/NASTRAN VERSUS SINDA, A NONLINEAR THERMAL TRANSIENT STUDY
#3889 (No Text Available)
Sasan C. Armand -- NASA Lewis Research Center, Cleveland, OH

To obtain the text, please contact the author directly at the following address:
Sasan C. Armand
NASA Lewis Research Center
Cleveland, OH

SIMULATION OF SMALL STRUCTURES-OPTICS-CONTROLS SYSTEM WITH MSC/NASTRAN (Acrobat 1194K) #3989, 19 pgs.
Ernest B. Paxson Jr. -- Generagl Atomics, Kirtland Air Force Base, New Mexico

ABSTRACT: This paper explains the implementation of MSC/NASTRAN as applied to the analysis of a Small Structures-Optics-Controls System, a sketch of which is shown in Figure 1. The SSOCS comprises a Beam Steering Mirror (BSM) supported by two Voice-Coil Actuators (on structural support springs "8" and "9") which changes the position of the BSM, a Disturbed Mirror, a Sensor which monitors translational and angular misalignments in the beam path, and a Controller which receives the error signals from the Sensor and sends correction signals to the VCA's. The response of the SSOCS to a step function disturbance applied to the structure of the DM via F7(t) through M7 (between springs "7" and "57") was calculated by MSC/NASTRAN; and, the results were compared against those computed for the SSOCS by a general purpose dynamics analysis program called TIMRSP. The agreement between the results of MSC/NASTRAN and TIMRSP was considered excellent.

DYNAMIC ANALYSIS WITH GAPS (Acrobat 377K) #4089, 8 pgs.
Viktor Wilhelmy, Ph.D. -- Structural Dynamics Research Corporation, Milford, OH

ABSTRACT: During the 1988 MSC World User's Conference User Forum, a number of delegates addressed the issue of dynamic analysis of structures with variable connectivity or boundary conditions. In this presentation, a very effective and versatile alternative to using gap elements, where some difficulties have been reported, is illustrated using NOLIN "elements" in the dynamic analysis of industrial machinery.
A variety of nonlinear effects can be modeled by combining the NOLIN tables with linear springs and other elastic elements. The examples include results obtained using a modal model together with numerical integration.

APPLICATIONS OF A SELF-ADAPTIVE ALGORITHM TO NONLINEAR FINITE ELEMENT ANALYSES (Acrobat 842K) #4189, 26 pgs.
Sang H. Lee, Steve S. Hsieh, and Rongfu Ou -- MSC, Los Angeles, CA

ABSTRACT: The accuracy and effectiveness of a nonlinear finite element solution rely upon several critical procedures: spatial discretization, material modeling, incremental time (or load) stepping, and equilibrium iteration. Performance and user friendliness can be improved if these procedures have intelligence to cope with any numerical difficulties without requiring user discretion. Adaptive mesh generation and refinement has become a major research topic to automate finite element modeling or spatial discretization. MSC/NASTRAN facilitates the adaptation of the constitutive relations by using a subincremental scheme in the material processing. This paper focuses on the adaptive incremental and iterative solution technique.
A self-adaptive algorithm for the time-stepping and equilibrium iteration was recently implemented for the nonlinear transient analysis in MSC/NASTRAN. This algorithm adopts Newmark's one-step integrator, which is suitable for the adaptive implicit integration. Before each step of direct integration, a proper time increment is estimated based on the dominant frequency of vibration. Equilibrium is attained by the Newton's iteration process at each time step. The iteration method employs expedient procedures such as the quasi-Newton update and line search technique. Divergence problems are overcome by the systematic stiffness matrix update and the bisection process. This adaptive procedure is also applicable to static analysis by simply ignoring the inertia and damping effects.
Several numerical examples are illustrated to demonstrate the applicability of the present method to a wide variety of nonlinear analyses. Geometric nonlinear effects are included in a shallow dome with an apex load, an elliptic cylinder subjected to an internal pressure, and a column excited with an axial follower force. A contact problem is introduced in an elastic rod subjected to an impact in the longitudinal direction. The material nonlinearity is combined with the geometric nonlinear effects in an elasto-plastic beam subjected to an impulse and a z-shaped frame loaded with a static force. The last example is a static problem which is analyzed without inertia and damping effects, and the automatic time step adjustment is bypassed.

LIMITATIONS OF CURRENT NONLINEAR FINITE ELEMENT METHODS IN DYNAMIC ANALYSIS OF SOLAR ARRAYS (Acrobat 836K) #4289, 14 pgs.
Paul A. Bosela -- Cleveland State University, Cleveland, Ohio

ABSTRACT: Deployable solar arrays consist of a "blanket" of solar collectors, and a mast. The blanket is stretched into position when the array is deployed. The stiffness of the array is a function of the rigidity of the mast as well as the tension in the blanket. Current finite element frequency analysis consists of using MSC/NASTRAN solution 4 to obtain the tangential stiffness matrix of the array. This matrix is then input, using DMAP alters, into MSC/NASTRAN solution 63 to obtain the natural frequencies of the array. The author has found that pseudo-forces are developed, however, at the element level due to limitations inherent in the geometric stiffness matrices currently in accepted use. In particular the geometric stiffness matrices lack the capability for rigid body rotations, especially when the rotations are large. The author demonstrates the limitations of the analysis, shows where the errors are introduced in the derivation of the geometric stiffness matrix, and examines various techniques either to eliminate the pseudo-force generation and/or improve upon the convergence of the current algorithms. This paper is the product of a NASA/ASEE summer faculty fellowship and an on-going joint research effort between Cleveland State University and the NASA Lewis Research Center.

CONTACT PROBLEMS IN MECHANICAL JOINTS (Acrobat 589K) #4389, 11 pgs.
John Furno, William J. Anderson, and Rui Orlandi -- The University of Michigan, Ann Arbor, Michigan

ABSTRACT: The opening of prestressed bolted joints under harmonic loading is studied. The problem is motivated by the bolted joint between the lower end and main body of an automobile engine connecting rod. This is a preliminary report of a student project currently underway.

EFFICIENT AND ACCURATE PROCEDURES FOR CALCULATING DATA RECOVERY MATRICES FOR SUPERELEMENT MODELS #4489 (No Text Available)
Christopher C. Flanigan -- SDRC, Inc., San Diego, CA

ABSTRACT: A data recovery matrix relates the interior responses of a superelement to the displacements and accelerations of the boundary degrees of freedom. This technique is extremely useful for launch vehicle dynamic loads analysis and other superelement static and dynamic analysis.
Procedures are described for efficiently calculating data recovery matrices for superelement models. Special techniques are employed to minimize the computational effort. The mode acceleration method is included to provide accurate element forces, stresses, and interface loads. Several checks are automatically performed to assess the accuracy of the model and the data recovery matrices. User input is also simplified to make the methods easy to learn and use. The procedures are implemented in two DMAP sequences for single-level and multilevel superelements. The procedures are illustrated in a sample problem.

To obtain the text, please contact the author directly at the following address:
Chritopher C. Flanigan, Director, Aerospace Projects
SDRC, Inc.
11055 Roselle St.
San Diego, CA 92121

USING SUPERELEMENTS FOR RESPONSE SPECTRUM AND OTHER HANDY ALTERS (Acrobat 924K) #4589, 17 pgs.
Ted L. Rose -- MSC, Los Angeles, CA

ABSTRACT: Several DMAP ALTERS are presented to allow the user to use Superelements in MSC/NASTRAN to obtain additional information from their analysis. These ALTERS include using Superelement data recovery in Response Spectrum analysis, performing Response Spectrum analysis without using a SUPORT, performing Superelement level buckling analysis, and using Image Superelements in a Global-Local force method analysis.

INERTIA RELIEF SOLUTIONS OF LARGE FINITE ELEMENT MODELS WITH APPLICATIONS OF MULTIPLE EXTERNAL SUPERELEMENTS (Acrobat 1237K) #4689, 16 pgs.
P. Zavareh and M. McNamee -- United Technologies, USBI, Huntsville, Alabama

ABSTRACT: The Space Shuttle Challenger accident triggered a complete recertification effort by NASA on all components of the Solid Rocket Booster. Stress analysis of the SRB components and assemblies was part of the recertification effort. The subject of this paper is the stress analysis of the Frustrum. The analysis was accomplished by substructuring with the use of superelement techniques and inertia relief method of analysis as provided by MSC/NASTRAN Solution Sequences 61 and 91. The SRB Frustum is designed to provide housing for the forward separation motors which provide the thrust force to separate the SRB from the external tank at SRB burnout. It also provides support for the main parachutes, decelerating subsystem and nose cap thruster firing loads. The Frustum was divided into six superelement of which five were external. All external SE attached to the residual structure boundaries of the primary SE by means of the databases CSUPER cards and DMAP alters. Particular attention was paid to the output coordinate systems at the superelement interfaces. In summary the results of the analysis compared favorably with previously generated Frustum full scale test data.

AN APPLICATION OF NEW TECHNIQUES FOR INTEGRATING ANALYTICAL AND EXPERIMENTAL STRUCTURAL DYNAMIC MODELS (Acrobat 1483K) #4789, 25 pgs.
Dr. John C. O'Callahan, Peter Avitabile, and Robert Riemer -- University of Lowell, Lowell, Massachusetts

ABSTRACT: Several techniques are presented which are used in a variety of ways to integrate analytical and experimental modal data bases. These techniques span the range of correlation of analytical and experimental modal data, estimation of rotational degrees of freedom for experimental modal data to be used in system modelling and modification studies, analytical model improvement based on the measured modal vectors, and nonlinear response techniques using reduced models. General theoretical background is presented for the techniques identified. A simple structure is used for demonstration of the integration of the analytical and experimental modal data bases.

FINITE ELEMENT MODEL UPDATES USING MODAL TEST DATA #4889, (No Text Available)
K.C. Jiang -- Ford Aerospace Corporation, Palo Alto, CA

ABSTRACT: An MSC/NASTRAN DMAP alter package has been written to improve finite element models using modal test data. This DMAP alter package is based on the AMI method developed by Berman and Nagy. The method first calculates the full modes by using test modes and natural frequencies then updates the mass and stiffness matrices. To improve the mass matrix, the AMI method uses the modal orthogonality equation as a constraint and selects an objective function of the difference between the analytical mass and updated mass matrices. The final step is to minimize the objective function and calculate the improved mass matrix by applying Lagrange multipliers with the measured modes. Similar procedures are used to update the analytical stiffness matrix by using the improved mass matrix, measured modes and natural frequencies. The theory of AMI method is briefly introduced. The detailed DMAP alter package to implement the AMI method into MSC/NASTRAN and a numerical example are discussed.

To obtain the text, please contact the author directly at the following address:
K.C. Jiang
Ford Aerospace Corporation
3939 Fabian Way
Palo Alto, CA 94303

STATIC AND DYNAMIC FEM/TEST CORRELATION OF AN AUTOMOBILE BODY
#4989 (No Text Available)
Hadi Rabbani -- Ford Motor Company, Dearborn, Michigan

ABSTRACT: The purpose of this study is to compare the results of static and dynamic finite element analysis with those of tests. Automobile structures are inherently complex and generally difficult to simulate accurately. Using the results of a correlation study, one can determine the validity of a finite element model and establish guidelines for simulating complex structures.
This paper deals with certain areas of vehicle FEM that are responsible for good correlation. For example, correct simulation of spot welds, "crimped" boundaries, joints, and flanges are of extreme importance in FEM/Test correlation. In static correlation, the finite element analysis results for bending and torsion of the full car are compared to those from testing. For dynamic correlation, the frequencies, mode shapes, and frequency response functions or selected points between test and analysis, are studied.

To obtain the text, please contact the author directly at the following address:
Hadi Rabbani
SYSTEM NVH
Ford Motor Company Md4
20,000 Rotunda Dr.
Dearborn, MI 48033

ANALYSIS OF 3-DIMENSIONAL LAMINATED COMPOSITE SOLIDS IN MSC/NASTRAN #5089
(No Text Available)
Hemant Patel and Gopal Nagendra -- MSC, Los Angeles, CA

ABSTRACT: A solid laminated composite brick element has been developed in MSC/NASTRAN. The element specifically addresses the modeling and analysis of arbitrarily laminated anisotropic thick composites where interlaminar shear stresses are critical and 3-D analysis is necessary in determining the stress field. The volume integration of the stiffness matrix is evaluated using a reduced Gaussian quadrature scheme to alleviate excessive element stiffness due to membrane and shear locking. Numerical results are presented for thick laminates under various geometry and loading configuration.

To obtain the text, please contact the author directly at the following address:
Gopal Nagendra or Hemant Patel
The MacNeal-Schwendler Corporation
815 Colorado Blvd.
Los Angeles, CA 90041-1777

SOFTWARE TOOLS FOR STRUCTURAL COMPOSITES ANALYSIS #5189 (No Text Available)
A. Mera and Steve Ward -- Boeing Computer Services, Seattle, Washington

ABSTRACT: BCS has surveyed several Boeing aerospace projects on the role of computer software for composite design/analysis tasks such as micromechanics, macromechanical properties, laminate layup and property optimization, analysis and design optimization, and detailed stress, strain, and strength checking. In addition to using capabilities of MSC/NASTRAN, PDA/PATRAN, I-DEAS and other commercial codes, advanced composite development projects have generated several software tools which now enjoy company-wide utilization.

To obtain the text, please contact the author directly at the following address:
A. Mera
Boeing Computer Services
P.O. Box 24346
M.S. 7L-23
Seattle, WA 98124-0346

ACOUSTIC-STRUCTURAL INTERACTION WITH MSC/NASTRAN: A REVIEW (Acrobat 914K) #5289, 14 pgs.
M. Cavaliere and S. DeRosa -- CIRA, Capua, Italy
L. Lecce and F. Marulo -- University of Naples, Naples, Italy

ABSTRACT: In this paper an attempt to review the acusto-structural interaction analysis capability of the MSC/NASTRAN is made. The pressure formulation and the velocity potential approach, are considered together with a complete assessment of the acoustic analogy from different point of view. Several numerical results are presented showing the comparison between theoretical and numerical applications. The effect of changing finite elements, and some specific parameters of the formulation are shown for both 2D and 3D models, giving some final considerations on the applicability and reliability, both for the theory and its numerical implementations.

CAD INTERFACE #5389 (no text available)
George Debush -- Advanced Design Resources, New Haven, Connecticut

ABSTRACT: The purpose of this paper is to present a procedure for solving a drop test simulation problem. It will present a solution of a real engineering problem of the kind which comes up in the development stage of most consumer products. The object is a tape rule made out of plastics, with a mechanism inside. In real life a tape rule has to withstand the drop from a given height onto a rigid surface and remain functional. Unfortunately, most drop tests are performed after the product is finished. The unfortunate part of it is that many products do not survive the test. That, in turn, entails redevelopment and reworking of expensive molds - a loss of time and money. The basic approach in finite element solution procedure is to transform potential energy into strain energy. The complete geometry of the product, made in 3D, is extracted from the CAD system into the preprocessing unit, whereas the constraints and loads are applied at different strain energy release rates while remaining in the domain of linear elastics.

To obtain the text, please contact the author directly at the following address:
George Debush, M.S.M.E.
Principal, Advanced Design Resources
25 Science Park
New Haven, CT 06511

LapCAD3 - A MODELING PROGRAM FOR MSC/pal AND MSC/NASTRAN (Acrobat 322K) #5489, 8 pgs.
Gert Lundgren -- LAPCAD Engineering, Chula Vista, CA

ABSTRACT: A description of LapCAD3 and an example.

MESHBASE - AN INTERACTIVE GRAPHICS PREPROCESSOR FOR 3-D FINITE ELEMENT MODELS (MESHES) (Acrobat 823K) #5589, 8 pgs.
Shyh-Yuan Kang -- Phoebus Systems, Los Altos, CA

ABSTRACT: Information on a finite element analysis is associated with a node or an element of the underlying finite element mesh. Quick identification of node and element numbers of vital to efficient manipulations of nodal and elemental information. An interactive graphic-interfaced processor, MESHBASE, has been developed on the Macintosh II for quick identification of node and element numbers on visible surfaces. MESHBASE allows a user to prepare, update and document nodal and elemental information such as nodal restraints, material properties, etc. by pointing directly at the hidden-line removed perspective plots of the mesh. Working in conjunction with spread sheet window, information including numerical data, text data, graphics and images can be easily stored, retrieved and updated.
MESHBASE is compirsed of 1) a 3-D graphics display/retrieving system that enables the user to identify nodes, elements, curves and surfaces of particular interest in real time by directly pointing at a 3-D meshplot, 2) a graphics file management system dn, 3) a spread sheet data base management system.. These systems are well integrated with the Macintosh window and system, a fast hidden line removal algorithm, and many unique mesh manipulation utilities for easy and intuitive mesh information processing.
MESHBASE employs an object-oriented approach and the Macintosh "cut and paste" capability for text, graphics and image manipulations. It is a powerful tool for preparing and documenting finite element model and output. It is also an information base for storing and retrieving other information such as experiment results and pictures, design drawings, remarks, assumptions, analysis results and graphics. MESHBASE is a very useful tool for engineering data organization and presentation.

PC STRESS ANALYSIS TOOLS FOR ENGINEERS (Acrobat 589K) #5689, 7 pgs.
Kenneth Ranger and Wai K. Ho -- MSC, Los Angeles, CA

ABSTRACT: A complete stress analysis package for engineers using IBM PCs has been redesigned and released by MSC. New features and enhancements have been implemented into MSC/pal 2 Version 3.5, MSC/cal version 2.5 and MSC/mod 1.5. Special versions of these products for the 80386 based machines have also been released. These new products take advantage of the 32-bit data structure and the extended memory beyond the 640K boundary. Timing comparison among the products are given in this paper.

A USER'S COMPARISON OF FINITE ELEMENT MODELING AND ANALYSIS TECHNIQUES (MAINFRAME VS. MICROBASED) FOR A THIN SHELL MODEL WITH TRANSITION SURFACES #5789 (No Text Available)
Avinash A Kenkare and Dr. Emory W. Zimmers, Jr. -- Lehigh University, Bethlehem, Pennsylvania

ABSTRACT: An identical problem was proposed to a mainframe based finite element modeling and analysis system, and a microbased system. The problem involved developing a thin shell model of a transition hopper between a pie shaped section, and a circular section. The critical modeling problem was that of the transition surfaces on the hopper. The performance of both systems was adequate i.e., the problem was solved by each. Differences existed, however, in modeling techniques, accuracy of results obtained, time required to perform the analysis, ease of results interpretation, and naturally in terms of price. The modeling techniques available with the mainframe based analysis system are considerably sophisticated as compared to the basic modeling techniques of the microbased system. The analysis performed was linear static analysis, and both systems were able to handle the problem at hand easily. A higher risk of error was felt to exist with the microbased system. The processing time for the microbased system was longer, but in terms of a real time comparison given the time-sharing nature of the mainframe, the microbased system performed favorably. The bigget plus identified for the microbased system was its price. This paper is intended to help calibrate the nature of microbased systems, and the trade-offs involved as migration toward microbased systems occur. A grading methodology developed was used to perform a weighted comparison of the two systems and their capabilities.

To obtain the text, please contact the author directly at the following address:
Avinash A. Kenkare
CIM Laboratory, Lehigh University
Harold S. Mohler Building
200 W. Packer Ave.
Bethlehem, PA 18015

DETERMINATION OF INFLUENCE LINES AND SURFACES USING MSC/NASTRAN (Acrobat 598K) #5889, 16 pgs.
Arturo Cifuentes -- MSC, Los Angeles, CA
Mario Pax -- University of Louisville, Louisville, Kentucky

ABSTRACT: This paper presents a simple yet general procedure to determine influence lines and surfaces for frames, beams, trusses, and plates. The method is based on the application for the Muller-Breslau principle and finite elements in combination with standard features of MSC/NASTRAN, a general purpose finite element code.

UTILITY PROGRAMS AT MARTIN MARIETTA WHICH SUPPLEMENT MSC/NASTRAN AND SDRC-SUPERTAB (Acrobat 950K) #5989, 8 pgs.
Roger W. Graves, Ted Anderson, and P. Richard Zarda -- Martin Marietta Missiles Systems, Orlando, Florida

ABSTRACT: Martin Marietta has many man-years of experience with MSC/NASTRAN and SDRC-SUPERTAB. Through constant use of this software, certain utilities, programs, and libraries have evolved that enhance the entire analysis process. It has been found that, collectively, these "utilities" provide a large productivity enhancements to the engineer by providing functions that were overlooked or not provided by SDRC and MSC. This paper documents the concept and function of many of these utilities with the hope that others may benefit by developing similar routines.

EXPERIENCES WITH MSC/NASTRAN AT INTECO #6089 (No Text Available)
G. Polosa -- INTECO, Rome, Italy

To obtain the text, please contact the author directly at the following address:
G. Polosa
INTECO
Rome, Italy

CAD/CAE/TESTING INTEGRATION AT NORTHRUP #6189 (No Text Available)
Shiv Bajaj -- Northrup, Hawthorne, CA

To obtain the text, please contact the author directly at the following address:
Shiv Bajaj
Northrup
8900 E. Washington Blvd.
Pico Rivera, CA 90660

INTERFACE BETWEEN FEM CODES AND PRE/POST PROCESSOR CODES
#6289 (No Text Available)
Mr. Heib -- Daimler Benz, Stuttgart, West Germany

To obtain the text, please contact the author directly at the following address:
Mr. Heib
Daimler Benz
Stuttgart, West Germany

FEM/SINDA: COMBINING THE STRENGTHS OF MSC/NASTRAN, SINDA, SUPERTAB, AND PATRON FOR THERMAL AND STRUCTURAL ANALYSIS (Acrobat 1697K) #6389, 14 pgs.
P. Richard Zarda, Ted Anderson, and Fred Baum -- Martin Marietta Missiles Systems, Orlando, Florida

ABSTRACT: This paper describes the interface/integration between FEM/SINDA, a general purpose geometry driven thermal analysis code, and the FEM software: SUPERTAB, PATRAN, and MSC/NASTRAN. FEM/SINDA brings together the advantages of the finite element method to model arbitrary geometry and anisotropic materials and SINDA's finite difference capability to model thermal properties, loads, and boundary conditions that vary with time or temperature. SUPERTAB and PATRAN thermal entities are directly supported since FEM/SINDA uses the nodes of the FEM model as the point at which the temperature is determined. Output from FEM/SINDA can be used directly by MSC/NASTRAN for structural analysis.