MSC 1979 World Users' Conference Proceedings

The conference proceedings for the 1979 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). These papers are listed alphabetically.

APPLICATION OF A SUBSTRUCTURE TECHNIQUE FOR STS/PAYLOAD COUPLED MODAL ANALYSIS (Acrobat 1.04MB) #0179, 17 pgs.
Allan R. Cohen and Robert M. Laurenson--McDonnell Douglas Astronautics Company

ABSTRACT: A procedure is presented for substructure modal analysis in which models of the components are initially incompatible. Such incompatibility exists when model generation and component modal reduction are performed by different organizations on different computer systems. The solution technique uses MacNeal-Schwendler Corp.'s version of NASTRAN (MSC/NASTRAN) to perform the analyses. The specific application discussed is the case where the substructures are the Space Transportation System (STS) and its payload. Theoretical development is discussed, along with a brief description of results. These results include comparison of substructured and unsubstructured coupled system frequencies and mode shapes for an example problem, and frequencies obtained from an actual STS/payload coupled analysis.

APPLICATION OF COMPONENT MODES TO THE ANALYSIS OF A HELICOPTER (Acrobat 957K) #0379, 18 pgs.
John R. Halcomb--MSC.Software Corporation

ABSTRACT: The now rather familiar helicopter model was used to compare the method of static condensation vs. the method of component mode synthesis. The helicopter model has developed along with MSC/NASTRAN. Originally the conventional solution, rigid format 3, normal modes was used for the analysis. The model was redefined using the superelement technique, fist as a single level substructing model and then into a multilevel substructuring model. Up to this point the Guyan method of static condensation was used to reduce the model from an original medium size static model to an acceptable size for normal modes analysis. With the development of the generalized dynamic reduction capability, the helicopter was reanalyzed using both superelements, generalized dynamic reduction and component mode synthesis.

APPLICATIONS OF NASTRAN IN AEROELASTIC ANALYSES AT NORTHROP (Acrobat 1.40MB) #0279, 20 pgs.
Ashok K. Singh--Northrop Aircraft, California

ABSTRACT: The NASTRAN finite element program has been actively used at Northrop since 1972 for static and dynamic analyses. Flutter and gust analysis capability was added to NASTRAN by MacNeal-Schwendler Corporation (MSC) under a NASA contract in 1976. The subsonic aeroelastic feature was acquired by the Advanced Structural Computer Methods (ASCM) group at Northrop in 1978 for evaluation. The group has been actively evaluating and exercising the various NASTRAN dynamics analyses features and the aeroelastic package for several months. The integrated NASTRAN flutter analysis is presently being used on several selected projects at the Company. The supersonic aerodynamic package will be evaluated as soon as it is made available to Northrop. This will probably take place in the early 1979.

A CRITIQUE OF THE MSC/NASTRAN FLUTTER ANALYSIS CAPABILITY (Acrobat 763K) #0579, 13 pgs.
Allen Deerhake--Convair Division of General Dynamics

ABSTRACT: Flutter analysis requirements of the cruise missle program demanded use of three dimensional aerodynamic theory. User of the solution 45 flutter analysis available within MSC/NASTRAN provided convenient access to the doublet lattice aerodynamic theory, since al the finite element models used for modal analyses had been constructed using NASTRAN.

CURRENT PLANS FOR MSC/NASTRAN (Acrobat 406K) #0679, 12 pgs.
C.W. McCormick--MSC.Software Corporation

ABSTRACT NOT AVAILABLE

DRAG METHOD AS A FINITE ELEMENT MESH GENERATION SCHEME (Acrobat 585K) #0479, 4 pgs.
S. Park and C.J. Washam--Control Data Corporation, Minnesota

ABSTRACT: The "drag mesh" method for automatic generation of finite elements is presented. Highlights of the techniques are;(1) simple, efficient element and node generation in regions of a structural model where a similarity of cross section is maintained; (2) exact model coordinate computation for surfaces and volumes of revolution and for many other doubly curve regions;(3) flexible user control of element and node numbering; (4) simultaneous of 1- 2-, and 3-dimensional elements.

GRAFAX- INTERACTIVE PRE AND POST-PROCESSOR FOR MSC/NASTRAN (Acrobat 3.68MB) #0879, 67 pgs.
J.L. Lambert--Engineering Systems Department, Wisconsin

ABSTRACT: GRAFAX is an interactive graphics system developed by A.O. SMITH Corporation. It is a proprietary computer program designed for use with MSC/NASTRAN. Pre and post-processing of FEM (Finite Element Model) data can be done at any location through the use of a graphics or RJE terminal connected to a time sharing system. GRAFAX is also available to run on some mini-computers.

IMPLEMENTATION OF SUPERELEMENT AT THE PRODUCTION LEVEL (Acrobat 1.23MB) #0979, 15 pgs.
David T. Zemer--The Northrop Corporation

ABSTRACT: In order to increase engineering productivity by more efficient use of computer resources the MSC/NASTRAN superelement capability was tested on an actual production model.

Comparisons made with the single structure approach have shown that the superelement technique is comparable in costs for a single run on large finite element models. This testing program has proven that the superelement method can result in substantial cost benefits for re-design or modification of any separate superelement structure. However, the testing program has also pointed out that it is extremely important for the analyst to understand and control the computer environment in which he works.

INCORPORATION OF MSC/NASTRAN, INTERACTIVE GRAPHICS AND DATA MANAGEMENT TECHNIQUES FOR COMPUTER AIDED DESIGN OF GAS TURBINE COMPONENTS (Acrobat 2.5MB) #1079, 21 pgs.
J. Kane and M. Propen--Avco Lycoming Division, Connecticut

ABSTRACT: The increased capabilities of modern computers and commercial analysis codes have made possible the complex and detailed analysis required to develop efficient and reliable turbine components subject to extreme mechanical and thermal loading. The major problems associated with utilizing this technology are concentrated in three areas:

• Generating efficient finite element models of complicated turbine structures.
• Organizing and condensing, into a manageable unit, the information resulting from detailed analyses.
• Ability for rapid modification and iteration based on the results obtained.

The paper describes an ongoing project at AVCO Lycoming which incorporates MSC/NASTRAN into an integrated turbine analysis system utilizing computer graphics. The initial phase of this work included software development to utilize MSC/NASTRAN's capability to output any user selected information involved in the course of an analysis to a data file. Geometry connectivity, displacement and stress output to tape, can be accessed and displayed by this software, allowing the engineer to interrogate in great detail complicated 3-dimensional structure models in a brief interactive graphics terminal session.

A case study is presented which illustrates the payoff associated with these methods.

INTERLAMINAR STRESSES IN A LAMINATED ANGLE BRACKET (Acrobat 3.25MB) #1179, 40 pgs.
W.F. Rahhal--Hughes Helicopters
J.Shek Ng--U.S.Army Aviation R&D Command
Satinder S. Sethee--Multiple Access, Inc

ABSTRACT: The interlaminar stress problem in an advanced composite laminated tension joint angle fitting has been investigated with the help of finite element, theoretical, and experimental methods. The finite element solution, using the MSC/NASTRAN program, was obtained by analyze two models; first model represented a solid laminate construction and provided the displacement/ force distribution to be applied on the refined laminated model of the critical strip. Two preprocessors were developed to automatically generate the input data required for the NASTRAN analysis on the basis of the given fitting parameters. The results obtained from the finite element and the theoretical method were found to be in good agreement.

MSC/NASTRAN ANALYSIS OF ELECTRIC CURRENTS IN CATHODIC PROTECTION SYSTEMS
(Acrobat 656K) #0779, 11 pgs.
John R. Brauer--Engineering Systems Department

ABSTRACT: Approach Heat of MSC/NASTRAN can be used to calculate electric current distributions in regions of variable electric current distributions in regions of variable electrical resistivity. This paper presents calculations made of electrochemical currents flowering in cathodic protection systems, the purpose of which is to prevent corrosion. In addition, convective heat boundary (CHBDY) elements are shown to be useful.

NUMERICAL STABILITY OF FINE MESH TORUS MODELS (Acrobat 1.87MB) #1279, 22 pgs.
James E. Sinkiewicz--University Computering Company

ABSTRACT: Numerical stability in Torus Models can only be verified with a full size model. Instabilities may occur when there are a large number of shell type elements around the circumference. Shell elements do not have inplane rotational Stiffness, Matrix. To study the effects and magnitudes of these terms a 30 degree segment of a Torus Model was analyzed utilizing Dynamic Reduction in Normal Modes Analysis.

A PRAGMATIC MSC/NASTRAN ENVIRONMENT (Acrobat 1.47MB) #1379, 21 pgs.
Steve Gratke--Vought Corporation

ABSTRACT: The Vought Corporation has taken a pragmatic approach to the development and control of its MSC/NASTRAN environment which involves the users, the computer system and operation, related software, and applications. This presentation describes Vought's overall organization and approach for dealing with the MSC/NASTRAN environment. This environment has evolved over a nine year period into a workable, adequate situation keyed toward an efficient man and machine utilization.

SDRC SUPERTAB- INTERACTIVE GRAPHICS AS A FRONT-END TO MSC NASTRAN DYNAMIC ANALYSIS
(Acrobat 1.25MB) #1479, 15 pgs.
John Jakovich and John Van Benschoten--Structural Dynaics Research Corporation

ABSTRACT: An interactive graphics model generation system, SDRC SUPERTAB will be discuessed to demonstrated its usefulness in cost-effective preparation of finite element models for MSC/NASTRAN analyses.

A specific application will be outlined pertaining to work performed by Structural Dynamics Research Corporation as an space shuttle component.

SOLVE LOCAL COLLAPSE A.O. SMITH GRAFAX (Acrobat 1.11MB) #1579, 20 pgs.
L.A. Larkin--Engineering Systems Department

ABSTRACT: SOLVE LOCAL COLLAPSE (SLC) is a newly implemented feature of AOS/GRAFAX, the pre-post- processing program for MSC/NASTRAN developed by the Engineering Systems Department of A.O. SMITH. SLC has been implemented within SECTION- a Major Function in AOL/GRAFAX - and provides post-processing capability for calculating eigenvalues and generating graphic displays of the buckled mode shapes for elastic local buckling of thin-wall CBAR and CBEAM elements.

STATIC ANALYSIS WITH MODIFIED ELEMENTS (Acrobat 519K) #1679, 12 pgs.
Robert L. Harder--MSC.Software Corporation

ABSTRACT: A new efficiency improvement is described for recalculating the static deflections after a change of a few structural elements. MSC/NASTRAN previously had modules (MODTA and MODEMG) which calculate the change in the stiffness matrix due to a change of element input data. The new improvement is an alternate solution procedure which avoids the decomposition of the modified matrix. The new procedure should be efficient only if the number of degrees of freedom associated with the changed elements is small, say less than one-fourth of the bandwidth of the stiffness matrix.

STATIC REDUCTION AND SYMMETRY TRANSFORMATION OF LARGE FINITE ELEMENT MODELS (Acrobat 796K) #1779, 12 pgs.
Andrew Mera--Boeng Computer Services, Washington

ABSTRACT: Static reduction and symmetry transformation are two independent matrix techniques available in NASTRAN for reducing the size of a finite element matrix before solution. This paper turns its attention to certain geometries, the optimum solution of which involves using the above techniques simultaneously.

For the special case of a structure exhibiting reflective symmetry at the substructure level, a matrix technique is developed for a one-shot reduction to a boundary matrix containing some or no degrees of freedom (d.o.f.'s) than the one obtained by NASTRAN's "mirror-image substructuring" technique.

Cost comparisons prove that the new technique offers significant advantages for substructures having a large percentage of d.o.f.'s on the plane of symmetry.