MSC 1981 World Users' Conference Proceedings

The conference proceedings for the 1981 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 334K) #0181, 10pgs.
R.H. MacNeal -- The MacNeal-Schwendler Corporation

Slide Presentation.

MSC/NASTRAN ON THE CRAY COMPUTER (Acrobat 471K) #0281, 11pgs.
C.W. McCormick -- The MacNeal-Schwendler Corporation

Charts and graphs.

DYNAMIC ANALYSIS OF AN ENGINE-TRANSMISSION ASSEMBLY - SUPERELEMENT AND COMPONENT MODE SYNTHESIS (oral presentation only) #0381
V.G. Philippopoulos -- Ford Motor Company

ABSTRACT: Automotive down sizing needs have offered finite element analysis techniques fresh opportunities to make a significant impact on the development/manufacturing of highly efficient modern powerplant designs by becoming an integral part of the design process. Efficient use of material in engine-transmission design calls for a thorough understanding of the dynamic behavior of the system. Due to the complexity of these parts, the finite element representation is usually a large model consisting of several thousand grids and elements. One single step eigen-solution approach is not practical to obtain vibration modes and frequencies. Superelement methods along with Guyan reduction is a possible solution technique. However, it is not a trivial task to select suitable ASET points in such systems to obtain reasonably good results. Component mode synthesis, on the other hand, would give acceptable results provided proper boundary conditions and adequate modes are selected for the components. This presentation examines Guyan reduction and component mode synthesis application to engine-transmission systems. Experimental results are expected to be available in time for the presentation.

SORTED OUTPUT IN MSC/NASTRAN (Acrobat 1.03MB) #0481, 23 pgs.
Howard J. Yang -- Teledyne Ryan Aeronautical

ABSTRACT: MSC/NASTRAN offers the capability to sort both forces and stresses. This capability will be demonstrated for static superelement output - DMAP1. Five sorting options exist. These options are : 1. SORT1 vs. SORT2 output, 2. selection of a specific stress or force to be sorted, 3. subcases to be sorted, 4. element set to be sorted, and 5. type of sort.

ARCHITECTURE OF NONLINEAR ANALYSIS FOR MSC/NASTRAN VERSION 61 (Acrobat 946K) #0581, 13pgs.
R.L. Harder, K.K. Karlsten, D.N. Herting, R. Narayanaswami -- The MacNeal-Schwendler Corporation

ABSTRACT: The development of non-linear analysis methods for a large-scale finite element system involves much more than transcribing analytic equations into computer codes. A large-scale system such as MSC/NASTRAN must be required to efficiently solve a diverse range of non-linear applications, ranging from soil mechanics to automotive crash dynamics, with problem sizes ranging up to thousands of degrees of freedom. Many types of material and geometric non-linearities must be considered along with the many types of finite elements currently required for the different applications. This paper describes the new nonlinear system which will provide a unique framework for these applications.

THREE-DIMENSIONAL ELECTROSTATIC FIELDS OF A HIGH VOLTAGE TRANSMISSION LINE
(Acrobat 1.0MB) #0681, 15pgs. John R. Brauer -- A. O. Smith Corporation

ABSTRACT: MSC/NASTRAN's heat transfer capability can be used to calculate electrostatic fields in three-dimensional regions of variable permittivity. This paper presents calculations of the electrostatic fields along a pole-type three-phase high voltage transmission line. Graphical displays of contours of constant voltage are presented at various locations along the line.

AN ALTERNATIVE METHOD FOR MODE ACCELERATION DATA RECOVERY IN MSC/NASTRAN (Acrobat 883K) #0781, 12pgs.
Christopher C. Flanigan -- General Dynamics Convair Division

ABSTRACT: An alternate method for mode acceleration data recovery has been developed for MSC/NASTRAN. Physical responses are recovered as a summation of their transient and steady-state contributions. The steady-state portion is calculated using static deflection analyses of the entire finite element model with inertial relief effects automatically included as required. The transient portion of the response is recovered from the modal responses of the truncated dynamic model. The alternate method for mode acceleration data recovery is substantially more efficient than MSC/NASTRAN's standard mode acceleration method for certain types of problems. In addition, data recovery is selective by employing the matrix method recovery module. Accuracy and efficiency comparisons are included. The alternate method has been implemented in MSC/NASTRAN using standard DMAP statements. Example problems are provided.

DYNAMIC STRUCTURAL RESPONSES TO RIGID BASE ACCELERATION (Acrobat 1.82MB) #0881, 31 pgs.
Thomas G. Butler -- Butler Analyses

ABSTRACT: NASTRAN has rigid formats which determine dynamic structural responses to excitations which are specified in terms of force time histories, but they do not address themselves to those cases for which the excitation is specified in terms of motion time histories, e.g. accelerations. A method is presented herein which is based on modifying the existing rigid formats with DMAP ALTER packets and/or using preprocessors or by composing DUMMOD's in new rigid formats. Only particular cases of motion time histories can be handled in the method being presented. The method restricts the excitations to rigid base accelerations. This implies that all input accelerations be synchronous and all excited points satisfy rigid body relationships. Methods are developed for responses to steady sinusoidal or transient accelerations to be solved by either direct integration or by the modal method. Specifically, modifications are provided to enable solutions via R.F.'s 8, 9, 11, and 12. This technique will hand most cases of support motion such as ground motion to building foundations, motions to bases of machinery, and shaker motion input to a test article.

USER DEVELOPED QUADRILATERAL SHELL ELEMENT FOR RF6 IN MSC/NASTRAN (Acrobat 880K) #0981, 14pgs.
Lawrence A. Larkin -- A. O. Smith Corporation

ABSTRACT: At the 1980 Conference, A. O. Smith presented newly developed RF6 elastic-plastic capability in MSC/NASTRAN. This new capability was a thin-wall beam element and a triangular shell element which would yield and deform plastically under bending loads. In the following will be presented a third elastic-plastic element - a quadrilateral shell element. The addition of this element has greatly enhanced our shell modeling RF6 analysis. The quad element is the principal 'workhorse' element because there are fewer elements required and because the element has much better in-plane or membrane stiffness characteristics than the triangular element.

DYNAMIC ANALYSIS OF OPTICAL SCAN SYSTEMS USING MSC/NASTRAN (Acrobat 1.0MB) #1081, 11 pgs.
William J. Nowak -- Xerox Corporation

ABSTRACT: This paper describes practical dynamic modeling and analysis of optical scan systems using MSC/NASTRAN. Simple spring and mass finite elements are used to represent the dynamic behavior of the system. Frequency and transient response solutions are presented based on representative dynamic loads induced during scan and re-scan operation. System response is characterized by image motion during image scanning and represented in the dynamic model by multi-point constraint equations. Linearization of the dynamic model, determination of representative forcing functions, and calculation of image motion coefficients are described along with listings of the actual NASTRAN data decks.

SIMPLE MODELING TECHNIQUE FOR DISTORTION ANAYSIS OF STEEL BOX GIRDERS
(Acrobat 1.36MB) #1181, 26 pgs.
Geerhard Haaijer -- U.S. Steel Corporation

ABSTRACT: Box-girder bridges are popular around the world because of aesthetics and because of the structural advantages resulting from the high torsional rigidity of box sections. However, thin-wall steel box sections tend to distort when subjected to asymmetric loads across the width of the structure. The distortion of the cross section results in transverse bending stresses and longitudinal normal warping stresses. To reduce these distortional stresses to acceptable levels, internal bracing with diaphragms or cross frames is commonly used in composite steel-concrete box girders. Analysis of the distortion by classical methods involves considerable mathematical effort that is beyond the scope of most design calculations. Specific bracing requirements could be established with the aid of complex finite-element models in which each component is modeled with appropriate elements such as MSC/NASTRAN QUAD4, BAR and ROD elements. The complete model, however, would have many degrees of freedom and would be costly to run. The present paper demonstrates a simplified approach that requires little computing effort. The concrete deck, webs, and bottom flange of the girder are each represented by a separate string of BAR elements. Through the use of multipoint constraint equations, the displacements of the strings are coupled to satisfy compatibility conditions at the junction of the webs to the concrete deck and bottom flange. Interior bracing members act as supports for the individual BAR strings. The procedure is illustrated by establishing the required spacing of cross frames for a typical mass-transit railway bridge.

PLANT TROUBLESHOOTING WITH MSC NASTRAN (Acrobat 1.56MB) #1281 23pgs.
Steven G. Masters -- E.I. Du Pont De Nemours & Company, Inc.

ABSTRACT: This paper deals with three troubleshooting cases where the use of Finite Elements played a major role. The Du Pont Engineering Department's workhorse structures program, MSC NASTRAN, was used in all three of the problems. Although these case histories may not be unique as far as analysis is concerned, it is hoped that the applications and modeling strategy will prove interesting and useful. All three examples involve diagnosing and correcting problems with existing equipment. One involves pressure pulsation in a fluid system; one deals with dynamic loading from an explosion; and one covers buckling of a tank support structure.

OVERVIEW OF MSC/NASTRAN HEAT TRANSFER CAPABILITIES (Acrobat 2.05MB) #1381, 40 pgs.
Rifat Keribar and J.C. Shang -- Gard Inc. / GATX Corporation

ABSTRACT: This paper outlines and appraises NASTRAN's heat transfer capability. The range of applicability of NASTRAN heat transfer is defined. Modeling techniques, input generation, computational accuracy and efficiency, and pre/post processing requirements are explored. This is accomplished through discussion of sample demonstration problems.

TRANSIENT THERMAL ANALYSIS OF A FUEL ROD CASING (Acrobat 839K) #1481, 12 pgs.
Jeffrey J. Bradford and William J. Treytl -- FMC Corporation

ABSTRACT: The application of the NASTRAN thermal analysis capabilities of the prediction of material strength after high thermal loading is presented. The investigation into the materials' strength involved a two-step analysis. The first step was to determine the materials transient thermal profile, which was followed by an elastic/plastic/creep analysis using the thermal profile as the structural loading. This paper presents only the thermal analysis phase of the investigation.

"COMMAND" ANALYSIS OF THE SHUTTLE THERMAL PROTECTION SYSTEM TILES (Acrobat 1.35MB) #1581, 18 pgs.
A.D. Dobrowski and J. Rowe -- Rockwell International

ABSTRACT: The Space Shuttle is protected thermally during atmospheric entry by approximately 31,000 silica tiles individually bonded to the substructure. The tile system must remain intact during all phases of the flight, sustaining loads imposed during ascent and descent in order to ensure a successful mission. The large quantities of complexly shaped tiles dictated the development of specialized, analytical approaches. This paper presents the computer program developed to analyze these tiles and automate the analysis of the Shuttle thermal protection system.

A STUDY OF THE EFFECT OF CONTROL SURFACE AERODYNAMICS ON FLUTTER ANALYSES (Acrobat 824K) #1681, 24 pgs.
Dr. Daniel Turner and Donald C. Astle -- Beech Aircraft Corporation

ABSTRACT: The subsonic unsteady aerodynamic computer programs tend to over predict the aerodynamics at the wing/control surface interface. In the past when using strip theory aerodynamics to insure that this effect was not critical to the flutter analysis, parameter studies were made using reduced aerodynamics on the control surfaces. To study the effect of using a matrix reduction technique with the MSC/NASTRAN Doublet-Lattice program, an analytical model of the Forsching, Triebstein, and Wagener experimental model was developed. A comparison of the various configurations were made. Additional configurations were analyzed and the effects of the various methods of modeling the wing/control surfaces on the flutter analyses are noted.

FINITE ELEMENT ANALYSIS: ADVANCED GRAPHICS SOFTWARE (Acrobat 1.57MB) #1781, 39 pgs.
John Jakovich -- Structural Dynamics Research Corporation

Slides and graphs.

INTRODUCTION TO THE GRASP SYSTEM (Acrobat 675K) #1881, 14 pgs.
David L. Herendeen and Jeffrey San Marco -- The MacNeal-Schwendler Corporation

ABSTRACT: This paper describes the GRASP system currently under development at MSC. The specific capabilities of this new interactive pre- and post-processing system, designed to provide interactive support for MSC/NASTRAN, are discussed and illustrated with examples taken from a typical engineering analysis.

INTEGRATION OF DEDICATED VAX/NASTRAN AND DISTRIBUTED INTERACTIVE GRAPHICS
(Acrobat 1.14MB) #1981, 18 pgs.
R.L. Ingle -- McDonnell Aircraft Company

ABSTRACT: The development of MSC NASTRAN on minicomputers offers users another alternative for engineering computer processing. This paper describes the ongoing distribution of the McDonnell Aircraft Company NASTRAN system. The latest addition to this distributed processing transformation is VAX/NASTRAN with DECNET communications. A Digital Equipment VAX 11/780 computer dedicated to NASTRAN with DECNET communications was tested. The test description and results are presented.

MODELING STRATEGY AND SEMI-AUTOMATED CONNECTIVITY CHECKING FOR LARGE SIZE FINITE ELEMENT MODELS (Acrobat 2.55MB) #2081, 44pgs.
L.I. Nagy and G.C. Campbell -- Ford Motor Company

ABSTRACT: This paper outlines modeling strategy for finite element analysis of large size problem. A semi-automated method is presented to assembly component models, tear down over-all model into arbitrary sub-assemblies or Super Elements, and verify the correctness of connectivities. The utilization of the method is demonstrated throughout a simple example problem. The listing of the employed computer codes are also included.

FINITE ELEMENTS ANALYSIS AND COLOR GRAPHICS (Acrobat 1.41MB) #2181, 11 pgs.
Robert G. Belie -- Air Force Weapons Lab / ARAC

ABSTRACT: Computer generated graphics has become an important part of finite element analysis. Mesh plots and deflection plots are both accepted as standard tools of the trade, yet over the last ten years, computer speed and memory and the sophistication of programs like NASTRAN have far out distanced the capabilities of the man-machine interface. The addition of color to computer graphics is now becoming economically practical and has the potential to span this gap between man and machine.

AOS/GRAFAX INTERACTIVE PROCESSING OF MSC/NASTRAN SUPERELEMENTS (Acrobat 1.49MB) #2281, 25pgs.
Erin L. Riley, James L. Webster, and Vern D. Overbye -- A. O. Smith Corporation

ABSTRACT: AOS/GRAFAX, the commercially-available interactive graphics system for pre- and post-processing MSC/NASTRAN, has been expanded to accommodate multilevel superelements. The VIEW function now has the following additional features: 1. prepare GRID card SEID for user-selected substructures, 2. create secondary superelement exterior GRIDs and CSUPER card, 3. plot and add undeformed and deformed superelements by SEID sets. A new function reorders exterior GRIDs optimally for cost-effective boundary and residual-structure superelement solutions. Practical applications of these features are presented.