MSC 1982 World Users' Conference Proceedings

The conference proceedings for the 1982 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).

MSC/NASTRAN STATUS REPORT (Acrobat 18.1MB) #0182, 29pgs.
R.H. MacNeal -- The MacNeal-Schwendler Corporation

A PowerPoint presentation.

MSC/NASTRAN AT THE UNIVERSITY OF MICHIGAN (Acrobat 1.15MB) #0282, 14pgs.
W.J. Anderson -- The University of Michigan

ABSTRACT: The University of Michigan's Engineering College was the first university group to sign up for MacNeal-Schwendler's new University Program which allows use of MSC/NASTRAN for educational purposes. Since implementation of the code on the University's Amdahl V-8 in April of 1981, a sequence of courses, television tapes and engineering summer conferences has been based on the use of MSC/NASTRAN. This has required the development of lecture notes, audio-visual aids and laboratory materials. Student reaction has been very favorable. MSC/NASTRAN has allowed completion of a number of student projects, including analyses of race car bodies, hydrofoils, sailboats and rocket motor cases. A total of 223 engineers will have been trained with MSC/NASTRAN in the 1981-1982 school year, including engineering summer conferences.

MSC/NASTRAN IN THE UNIVERSITY ENVIRONMENT (Acrobat 470K) #0382, 7pgs.
Victor Genberg -- University of Rochester

ABSTRACT: The availability of MSC/NASTRAN on campus meant that the simple textbook finite element programs were no longer necessary in the graduate finite element course. This highly popular course, which is open to seniors, has homework problems of textbook form, as well as actual NASTRAN assignments.

AN MSC/NASTRAN-CAD APPLICATION IN ORTHOPEDICS (Acrobat 2.02MB) #0482, 10pgs.
Nancy J. Lambert -- A.O. Smith Corporation

ABSTRACT: Much attention is focused on the combination of interactive computer graphics with large scale engineering analysis systems such as MSC/NASTRAN. The productivity increase from this combination of technologies has indeed been dramatic. A particularly interesting aspect of the synergism is the insight offered to the analysis of unusual structural design interation is described.

ELECTRICAL AND THERMOSTRUCTURAL ANALYSES OF POTTED HIGH-VOLTAGE ELECTRONIC DEVICES (Acrobat 2.30MB) #0582, 24pgs.
Donna K. Archipley-Smith and Henry H. Fong -- PDA Engineering

ABSTRACT: This paper presents the results of a nine-month 1981 study aimed at understanding the electrical and thermostructural behavior of a potted gun assembly of a traveling wave tube (TWT) used in a communications satellite.

SEISMIC ANALYSIS OF COUPLED FLUID-STRUCTURE RESPONSE (Acrobat 3.24MB) #0682, 41pgs.
Hiroshi Saito and Masaaki Watanabe -- Mitsubishi Research Institute

ABSTRACT: To predict the dynamic characteristics of structures with containment fluid, finite element representation of the pressure field within the fluid is employed. A moderate DMAP modification with MSC/NASTRAN makes a convenient analysis procedure for this purpose. Numerical examples as well as discussions on lumped/consistent formulation of fluid-structure coupling are presented.

USING MSC/NASTRAN TO SOLVE SYMMETRIC STRUCTURES WITH NONSYMMETRIC LOADS
(Acrobat 1.58MB) #0782, 17pgs.
Thomas G. Butler -- Butler Analyses

KINETIC ENERGY DMAP FOR MODE IDENTIFICATION (Acrobat 2.59MB) #0882, 30pgs.
G.R. Parker and J.J. Brown -- Hughes Helicopters, Inc.

ABSTRACT: The ability to solve large dynamic finite element problems of high modal density has increased the difficulty of modal identification. As an aid in overcoming this difficulty, the concept of kinetic energy of modes is utilized. With this aid, structural as well as local modes can be quickly isloated. This paper presents the DMAP alter package and examples of how this method was applied to the NASTRAN dynamic analysis of the Hughes Advanced Attack Helicopter.

THE BEHAVIOR OF PRESSURE VESSELS WITH VARYING THICKNESS (Acrobat 1.41MB) #0982, 24pgs.
Joe E. Longwell --Vought Corporation

ABSTRACT: The motor case for an air-launched missile was analyzed using MSC/NASTRAN's SOL 64. The shell was thickened at the top for support purposes and caused large positive radial deformations to occur at the top and bottom and negative radial deformations to occur at the sides when burst pressures were applied. The non-circular shape of the motor case cross section had a significant influence on the stiffness of the structure which exhibited geometric non-linear behavior. Several NASTRAN models, including a solid element model and several plate element models, were used to analyze the motor case.

MSC/NASTRAN SUPERELEMENT ANALYSIS (Acrobat 3.61MB) #1082, 44pgs.
Paul A. Larkin and Michael W. Miller -- Fairchild Space and Electronics Company

ABSTRACT: This paper describes a practical application of the use of multilevel/external superelements using MSC/NASTRAN through a typical example and Fairchild's related experience. The objective is to demonstrate the effectiveness of superelement analysis with regard to time and cost savings through an analysis by parts approach. This paper does not address the theoretical development and/or use of superelements, that information is plentiful and readily available. Several sources of superelement theory have been listed in section 9.0 at the end of this paper for those who are interested.

PLY AND RUBBER STRESSES AND CONTACT FORCES FOR A LOADED RADIAL TIRE
(paper not available)
Michael J. Trinko -- Goodyear Tire and Rubber Corporation

ABSTRACT: A multi-layer geometric non-linear finite element model of a 215/75R15 steel belted radial tire is subjected to inflation and footprint loading, and the resulting stresses in both the rubber and the plies are presented. Assumptions include fixed boundary conditions at the bead-flange interface, linear material property representation and symmetry with respect to the diametrical and tread centerline planes. The footprint loading is simulated by enforcing vertical displacements at selected nodes of the model to yield a contact path force distribution. In-plane patch forces are not included. Experimental results are given showing comparisons with the analytical predictions. Advantages of this approach over models which have been given earlier are the capability to extract information from each layer and to apply displacements directly to the contact patch rather than using a Fourier approach. The model is exercised using the MSC/NASTRAN program. The straight-forward restart capability along with the ability to include/exclude nodal points in the patch contact set during the iteration process make the MSC/NASTRAN program convenient to use for this class of problem.

ROTOR-DISK SYSTEM GYROSCOPIC EFFECT IN MSC/NASTRAN DYNAMIC SOLUTION
(Acrobat 1.42MB) #1282, 21pgs.
Herand Bedrossian and Nicholas Veikos --Avco Lycoming Division

ABSTRACT: The analysis examines the nonlinear equations of motion governing a rotating structure and determines how they can be accurately represented using MSC/NASTRAN dynamic solutions. In particular, methods are developed and described which generate a skew-symmetric matrix and couple this to the MSC/NASTRAN analysis using direct matrix input in order to simulate the disk gyroscopic effect. These techniques will now allow for the analysis of nonsynchronous as well as synchronous whirl in a rotor-disk system using MSC/NASTRAN. The techniques are demonstrated using three different NASTRAN solutions - NORMAL MODES (SOL:3), DIRECT COMPLEX EIGENVALUE (SOL:28), and DIRECT FORCED RESPONSE (SOL:26). The results show excellent correlation with closed form solutions for forward and reverse precession as well as nonsynchronous whirl frequencies.

EXTENSIONS OF MSC/NASTRAN TO SOLVE FLEXIBLE ROTOR PROBLEMS
(Acrobat 1.13MB) #1382, 19pgs.
I.U. Ojalvo --Perkin-Elmer Corporation

ABSTRACT: The general dynamic equations associated with rotating flexible bodies differ from those used to analyze nonrotating structures in a number of ways. Besides accommodating the usual mass and stiffness matrices, an appropriate finite element code for such problems must be capable of including Coriolis and centrifugal acceleration terms. These latter terms arise from the use of a rotating coordinate system which nominally follows the flexible body as it rotates. If part of the structure does not rotate, such as with a rotor housing, the computer program must also accommodate multiple rotating and nonrotating coordinate systems. In this paper, the additional rotor acceleration terms are derived and their implications are discussed from both a physical and computational point of view. Particular attention is devoted to flexible bearing, dynamic shift of initial imbalance, Coriolis and centrifugal effects. Interpretations of the steady-state forces on both the rotor and housing are presented and the requirements for using the MacNeal-Schwendler Corporation modified version of NASTRAN (MSC/NASTRAN) on such problems are given. In addition, a low speed iterative solution approach is described and tested on simple examples for which the exact solutions are known. By comparing the known exact solutions with the approximate ones, the proposed iterative solution accuracy and convergence rates are heuristically inferred.

COUPLED BLADE-DISK VIBRATION ANALYSIS BY SUPERELEMENT AND CYCLIC SYMMETRY METHODS (Acrobat 512K) #1482, 6pgs.
Leo K. Lu -- Westinghouse Electric Corporation

ABSTRACT: When blades of reasonable length are attached to a disk, the characteristics of the resulting vibratory system are more complex. The modes of the combined system do not, in general, correspond to the modes of the components of the system, that is, the blades and the disk. Very often 'long' turbine blades are shrouded "harmonically." It is important to analyze the situation when the number of blade groups in a row do not coincide with the resonant harmonic. In this study, typical blade-disk assemblies are analyzed using the NASTRAN Finite Element Program. Because of the repetitive pattern of the blade groups, substructural modal synthesis and cyclic symmetry approaches are used. The agreement in output illustrates the validity of both methods. The results are then discussed.

MESH OPTIMIZATION FOR MODELING NOTCH STRESSES (Acrobat 1.36MB) #1582, 27pgs.
Paul D. Ruffle -- Honeywell, Inc./Defense Systems Division

ABSTRACT: A parametric study has been done to determine the best finite-element mesh, using QUAD8 elements, to predict the stress distribution adjacent to the notches in the plastic sabot used on a 25mm projectile. A sabot is a sleeve of low-density material used to support a subcaliber projectile in a gun barrel and then break up at muzzle exit. The objective of the study was to find the most efficient mesh to model the sharp stress gradient that exists at the apex of the notch when the projectile is subjected to a high angular velocity causing circumferential tensile stresses in the sabot. Ten different cases were analyzed and several were found to give good results.

EVALUATION OF CERAMIC SUBSTRATES FOR PACKAGING OF LEADLESS CHIP CARRIERS
(Acrobat 437K) #1682, 8pgs.
Alson E. Hatheway -- Alson E. Hatheway, Inc.

ABSTRACT: AEH is performing extensive analysis and test work to develop analytical tools for predicting stress levels and thereby prevent failures in electronic assemblies composed of ceramics, metals and glass reinforced plastics when exposed to high level random vibration environments. The task is to determine a simple modeling procedure which will provide accurate results and which will be easy to verify during tests. The early work has been reported previously. Although the reported results were acceptable, it was felt that limitations on the software routines being used were handicapping the accuracy of the results. The initial work used the SAPV2 software package which (1) would not accept orthotropic materials properties, (2) would not accept damping as a function of frequency, and (3) would not calculate random responses. Subsequently, it was decided to adapt the model to MSC/NASTRAN to determine the extent to which the software handicaps influenced the results.

ADVANCES IN NONLINEAR ANALYSIS IN MSC/NASTRAN (Acrobat 657K) #1782, 18pgs.
D.N. Herting -- The MacNeal-Schwendler Corporation

ABSTRACT: New capabilities and improvements to existing code have been added to the nonlinear system for MSC/NASTRAN Version 62. The goal of the continuing project is to provide an advanced, general-purpose tool for nonlinear analysis using existing MSC/NASTRAN elements, constraints, and modeling conveniences. Major new features include three-dimensional nonlinear elements, transient analysis with geometric and material nonlinearities, and new Quasi-Newton solution methods. Several interesting test problems are presented to illustrate the system capabilities.

FMC NASTRAN INTERFACE SYSTEM (Acrobat 2.06MB) #1882, 22pgs.
Joel Gerdeen -- FMC Corporation

NASTRAN INPUT DATA PREPARATION USING THE FEM EDITOR (Acrobat 367K) #1982 6pgs.
Malcolm W. Ice and Frank J. Robl -- Boeing Computer Services Company

ABSTRACT: A software development project currently under-way at BCS is the FEM Editor, which provides special-purpose preprocessing capabilities for creating and modifying NASTRAN input data. Card image forms, one each NASTRAN card type, are displayed on a color graphics screen, along with descriptions of the card fields. Data input consists of filling out the form, tabbing from field to field, and editing and data generation using a command menu. The user selects the specific card form either through a menu traversal or by explicitly keying in the NASTRAN card name.

AOS/GRAFAX INTERACTIVE PROCESSING OF MSC/NASTRAN DYNAMIC RESULTS (Acrobat 7.15MB) #2082, 20pgs.
James E. Webster and Vern O. Overbye -- A.O. Smith Corporation

ABSTRACT: AOS/GRAFAX, the commercially-available interactive graphics system for pre- and post-processing MSC/NASTRAN, has been adapted to the requirements of dynamic analysis. A MODES case control card allows the display of element stress results by subcase for each output time request. Similar results may be obtained for grid data, such as deformed plots and loads. A small model is used to illustrate conventional and Superelement solutions for normal modes, buckling and modal transient analysis. Color stress contour plots and practical applications of these features are also presented.

BCS IMPLEMENTATION OF THE SDRC GRAPHICS SYSTEM (Acrobat 1.21MB) #2182, 13pgs.
Frank J. Robl and Malcolm W. Ice -- Boeing Computer Services Company

ABSTRACT: A BCS software development project currently under way will result in a unique implementation of the SDRC Graphics System (SGS). SGS includes SUPERTAB, which is an interactive graphics processor which creates finite element geometry, node and element loads, and boundary conditions. It also includes OUTPUT DISPLAY for postprocessing of NASTRAN command board consisting of a preprinted command menu mounted on a digitizing tablet. The menu contains the entire SUPERTAB and OUTPUT DISPLAY command repertoire. SGS is controlled by a succession of picks from the command board. In addition, two display screens are utilized, with graphics and labeling information written to a high resolution storage tube device, and textual information to the color raster screen.

FUTURE MSC/GRASP DEVELOPMENTS (Acrobat 431K) #2282, 10pgs.
D.L. Herendeen -- The MacNeal-Schwendler Corporation

ABSTRACT: The current status of the newly released MSC/GRASP post-processing system is briefly discussed. Planned developments for the next year, including automated mesh generation, text and graphics editors, new features, user interfaces, additional graphic devices and new host computers, are then outlined.

ABSTRACT: As MSC/NASTRAN finite element models increase in size and complexity, the demand on computer software, hardware and other resources may exceed those initially allocated for the project. Successful completion of a large finite element analysis often requires understanding resource utilization as measured in terms of computation time, volume of data handled and stored, cost, and human endurance.
The engineer is usually relieved of the resource management task by MSC/NASTRAN's sophisticated program structure and data management technology. The program has the capability to estimate the necessary CP time, I/O time, primary and secondary storage, compare against resources available on the particular computer model, and then automatically trade off certain limiting resources against others. For large problems, however, situations arise when the NASTRAN user is forced to intervene. He find it more efficient to schedule resources to match requirements. This competence is especially useful when computers with different characteristics are at one's disposal.
Several MSC/NASTRAN problems were run on Boeing Computer Services Company CYBER 760 and CRAY-1S computers. The results provided some interesting insights into MSC/NASTRAN's numerical algorithms, its relative performance on the above computers, and its utilization of vector processing on the CRAY.