1998 Americas Users' Conference

The conference proceedings for the 1998 Americas Users' Conference are now available on-line in Adobe Acrobat PDF format. The papers have been categorized by topic.

Categories

Aircraft

MSC/FLIGHT LOADS AND DYNAMICS VERSION 1 (Acrobat 237K) #1198, 8 pgs.
Greg Sikes and Douglas J. Neill--The MacNeal-Schwendler Corporation

ABSTRACT: For the past year, the MacNeal-Schwendler Corporation (MSC) has been actively developing solutions to the challenges faced by our customers in the area of external loads and aerodynamic response. Through strategic partnerships with the world's leading civilian and military air vehicle manufactures, MSC has developed an in-depth understanding of our customers' needs. These efforts have lead to the development of an integrated, process-driven external loads and dynamics system called MSC/FlightLoads and Dynamics.

PARTICULARITIES OF SINGLE SHEAR PIN JOINTS MODELING FOR MSC/NASTRAN (Acrobat 3.5MB) #3898, 12 pgs.
Adrian Viisoreanu--Boeing Commercial Airplane Group
Kris Wadolkowski--Aerostructures, Inc.

ABSTRACT: Inspired from the analysis of aircraft engine mount fittings, this paper presents techniques applicable to the solid modeling of single shear pin joints in MSC/NASTRAN. A parametric study describes the influence of some joint geometry parameters on the stress and bearing load distribution along the pin length. The effect of the residual stress induced by the bushing interference fit is also considered.

POSTPROCESSOR FOR AUTOMATIC MODE IDENTIFICATION FOR MSC/NASTRAN STRUCTURAL DYNAMIC SOLUTIONS WITH EMPHASIS ON AIRCRAFT FLUTTER APPLICATIONS (Acrobat 33K) #1498, 4 pgs.
Emil Suciu--Raytheon Systems Company
Joseph Buck--DeHavilland Inc.,Ontario

ABSTRACT: A practical procedure and postprocessor FORTRAN program which sums strain energies for an aircraft structure, elastic element by elastic element for each component as outputted by MSC/NASTRAN Solution 103 or Solutions 145 and 146 is described and an example is provided showing an output table of strain energies for a hybrid finite element model of a twin turboprop aircraft and comparison with a few plotted mode shapes. The application of the procedure to the .f06 output of one of the structural dynamic solutions results in automatic naming of the analytical modes of vibration, a powerful aid for the flutter analyst.

THEORETICAL VALIDATION AND DESIGN APPLICATION OF MSC/NASTRAN SNAP-THROUGH BUCKLING CAPABILITY
(Acrobat 293K) #1598, 15 pgs.
Dr. M.M. Moharir--The Aerostructures Corporation

ABSTRACT: MSC/NASTRAN's Snap-Through Buckling capability is validated using a closed form solution based on the large displacement theory and the nonlinear eigenvalue extraction procedure for flat and "slightly" curved thin plates. Excellent correlation is observed for displacements, stresses, and buckling loads at Snap-Through. The capability is used to design and analyze the leading edge of a large commercial airplane.

THREE DIMENSIONAL MODEL OF AN ARRAY OF PANEL BAYS INCORPORATING PRETENSIONED FASTENERS, PRECOMPRESSED FASTENER SURROUNDINGS, SHELL-TO-SOLID AND BAY-TO-BAY NASTRAN INTERFACE CONNECTORS (Acrobat 1.0MB), #3098, 21 pgs.
Steven Basic--Boeing Commercial Airplane Group

ABSTRACT: This paper extends applicability of the finite element method to the analysis of interaction between the main components of a panel bay (chords, webs and stiffeners) and an array of elastic fasteners on elastic plate-foundations.
The pre-tensioned fasteners and the pre-compressed fastener-surroundings of this model are three-dimensional fine-mesh-solid islands that are integrated into the rest of the plate-element structure using the new shell-to-solid Nastran Interface Connectors.

The outer cylinder mesh nodes of fasteners are connected to the fastener-bore mesh nodes with an array of substantially non-linear radial gap elements, whose radial stiffness may have two magnitudes.
The first run of the model will be made with the least possible radial stiffness of the gap elements. The main objective of this run is determination of the maximum stain gauge element stresses. The strain gauge elements are located at the outermost and innermost plate-to-hole edges.

The second run of the model will be made with a relatively high magnitude of the gap element radial stiffness generating a 'Filled Hole' mesh . The main objective of the 'Filled Hole' mesh is the reference stress determination at the hole edge strain gauge elements.

By definition, the maximum plate-to-hole edges to the reference stress ratios are the stress concentration factors 'Kt max' and 'Kt mm' at the outermost and innermost edges of the plates. This increase of the tensile and hoop stresses, relative to an inelastic fastener concept incorporating 'Kt mean' at the central lines of plates, is caused by an additional bearing stress component due to the fastener-to-fastened plate interference, in their elastically deformed configuration.

The Load Transfer Factor (LTF) will be calculated also in two stages. The first stage will be the same as that of the existing inelastic fastener methodology, i.e. the logarithmic magnitude of the LTF (that was substantiated with numerous tests) will be determined for a given ratio between bearing stress-flange thickness and the tensile stress -fastener diameter products.
Within the second stage a correction factor, to be applied to the LTF, will be established. This smaller than '1' correction factor will be found from increments of the the mean integral and the maximum 'Kt max' values of this model using the allowable stress for varying 'Kt', as obtainable from the Kinetic Theory of Solids and Reference [7].

Automotive

ADVANCED MODE SHAPE IDENTIFICATION METHOD FOR AUTOMOTIVE APPLICATION VIA MODAL KINETIC ENERGY PLOTS ASSISTED BY NUMBEROUS PRINTED OUTPUTS (Acrobat 488K) #1898, 17 pgs.
Manfred Wamsler-- Daimler-Benz AG
Ted Rose--The MacNeal-Schwendler Corporation

ABSTRACT: Design optimization procedures of full-vehicle simulation models - such a procedure as shown in this paper - require a very fast and reliable mode shape identification. Just because these simulation models necessarily contain a lot of large concentrated masses and mass moments of inertia, e.g., engine, gear, differential, car wheels, steering wheel, mufflers, airbags, and reduced masses from superelement processing, to name just a few, the kinetic energy method is especially destined to accomplish this task. In the present paper, a graphical Modal Kinetic Energy evaluation technique is described in detail. Moreover, the modal kinetic energy plots are a means to investigate the structure's eigenbevior in the low-frequency range, e.g., to see where dynamic vibration absorbers have to be attached and where bushings, and instrumentation for modal testing have to be placed. In summary, the presented graphs make even the most complicated subjects clear and provide the dynamicist with information he can use to achieve a better design quickly. The prints of significant values indicate the degree of coupling between energies in rotational and translational direction per mode and the energy portions of the physical residual chassis structure and the energy portions of appended body and subframe superelements. Representative applications for mode shape identification in automotive engineering, V70, are presented extensively in order to demonstrate the strength of the method. Surely, there are many other applications in the engineering structural analysis field where the advanced mode shape identification method will play key roles.

IMPROVED IDENTIFICATION OF CONTRIBUTING MODES IN SUPERELEMENT MODAL FREQUENCY RESPONSE ANALYSIS, V70 (Acrobat 325K) #2098, 15 pgs.
Manfred Wamsler-- Daimler-Benz AG
Ted Rose--The MacNeal-Schwendler Corporation

ABSTRACT: In parallel with experimental methods, modern-day cars are designed by advanced dynamic analyses using the Finite Element Method. These analyses help identify components sensitive to vibrations that could possibly lead to deterioration of ride comfort and safety. For correct simulation of the real dynamic behavior of a car all parts relevant to vibrations have to be taken into consideration when assembling a full-vehicle simulation model. Since this model contains many viscous dampers, such as shock absorbers, the steering damper, and several hydro-mounts for the engine/gear unit and the rear-axle support - when the modal transformation is applied for reduction purposes - the generalized damping matrix is not diagonal; that is, the modal equations remain coupled by the damping coefficients. Consequently, the dynamic response is composed of various contributions resulting from eigenvectors. Knowing the contributions from each mode shape is a very important requirement for taking suitable measures in order to decrease obnoxious vibration amplitudes, i.e., the modal contributors are a means of finding suitable locations for modifications aimed at improving the structure's dynamics. It is worthwhile to notice, that by the use of the presented procedure innovative redesigns may be found by the analyst which the automatic stuctural optimizers are never able to find. Guidelines on how to influence contributing modes in order to decrease high resonance peaks are given along with a V70 SOL 111 DMAP alter for the identification of contributing modes.

Civil

PVC SEWER SYSTEM SEISMIC ANALYSIS MADE PRACTICAL (Acrobat 520K) #0298, 14 pgs.
Hirokazu Nishiura--Sekisui Chemical Co., Ltd.
Eiichi Satoh--SC-Japan
David Bremmer--The MacNeal-Schwendler Corporation

ABSTRACT: MSC is announcing a new business offering based upon a breakthrough technology. MSC has developed a means by which design engineers or occasional CAE software users can reliably perform complex engineering analysis with the same resultant quality as do the dedicated analysis experts. This breakthrough technology captures the expert's engineering knowledge and specific process solution methodologies to enable and guide the novice. Now CAE can readily enhance the design processes where it was previously unavailable. Most importantly, large productivity gains are realized in the design process. The first practical test case for this technology was to solve the problem that prevented Sekisui Chemical Company from deploying their analysis methods for creating earthquake resistant designs.

Sekisui Chemical Co. has developed new earthquake resistant PVC pipeline components. To support this new materials technology, complex nonlinear FEA models for evaluating system performance under earthquake loading were developed. The challenge now is to integrate for practical use, the performance analysis methods into the design process for system layout.Sekisui wishes to provide earthquake resistance checks for all new drainpipe system designs.

Modeling of one sewer system layout, including selected earthquake loads and nonlinear soil behavior has required an average of 40-days for expert analysts. A radical departure from the traditional FEA modeling tool set is required to enable non-FEA-expert design engineers to use the developed sewer system analysis methodology.

A sewer system modeling application was written in the form of extended HTML drive pages similar to web pages. Automation functions were produced by capturing MSC/PATRAN session files from the manual analysis process as performed by an expert. The special application written for Sekisui will reduce the effort of producing sewer system analysis models from 40-days, to a matter of hours. Furthermore, it will allow design engineers who are not FEA, earthquake engineering, or soil engineering experts to perform the job with expert quality results.

Composites

COMPOSITE DESIGN EXPERIENCE USING MSC NASTRAN FOR THE HYDRODYNAMIC FAIRINGS OF A NEW SUBMERSIBLE (Acrobat 1.2 MB) #1698, 22 pgs
Dr. E. Thomas Moyer Jr., Dr. Richard Cobb and Mr. Kim Grubbs--Analysis and Technology Inc.
Dr. William Gordon--Northrop-Grumman Corporation, Oceanic Systems

ABSTRACT: This paper details our recent experiences designing the fairings for a new submersible vehicle being constructed. A unique composite material design approach was chosen to meet challenging structural requirements while minimizing weight. Analysis examples include material selection decisions, laminate design tradeoff studies, modeling of bolted joints, establishment of material allowables and global/local analysis approaches.

Design/Manufacturing Methods

APPLYING MSC/PATRAN AND MSC/NASTRAN TO IMPROVE THE DESIGN PERFORMANCE OF LARGE BULK MATERIALS HANDLING MACHINES (Acrobat 33K) #3798, 9 pgs.
R.C. Morgan, Dr. S. Loganathan, and Dr. F. Gatto--BHP Engineering Pty Ltd.

ABSTRACT: Bulk materials handling machines such as stackers, bucket wheel reclaimers, ship loaders and ship unloaders are complex moving structures with onerous loading and service conditions. Due to such factors there is the potential for many failure modes and problem areas on these machines.

Machines are normally purpose designed for the particular application at a port, mine or industrial facility. In the current environment, high reliability standards are required in order to provide operational security for business and safety to personnel.

Dynamic, buckling and non linear behaviour of such structures can all contribute to failures and operational problems. Hence a sophisticated analysis and modelling tool is required in order to provide adequate representation under service conditions.

Due to the complexity and size of these structures, models with large numbers of degrees of freedom are required for analysis. It was previously very time consuming and costly to carry out such work, putting it out of the realms of commercial application. However the compatibility of MSC/PATRAN with CAD systems and the ease of building large models, together with recent developments in the efficiency of the solvers in MSC/NASTRAN, opens new frontiers for engineers to critically examine the design of new structures before they are built.

Similarly, with the application of MSC/PATRAN and MSC/NASTRAN, existing machines can be critically examined and cost effective life extension strategies developed to deliver major economic benefits to owners.

MODAL QUALITY. THE KEY TO CAD/CAM/CAE INTEROPERABILITY (Acrobat 195K) #2398, 12 pgs.
Dan McKenney--International TechneGroup Incorporated

ABSTRACT: Today 3D CAD Models are driving a growing number of downstream CAD/CAM/CAE applications. When those involved in Finite Element Analysis, Rapid prototyping, Numerical Control, and Data Exchange functions can work directly with the original, clean CAD model the results are significant boosts to product quality, production costs, and time to market.

Unfortunately a growing number of CAD models contain hidden errors or anomalies requiring the models to be reworked by the downstream user. Studies show that FEA users, for example, are spending as much as 70% of their time fixing CAD models. Similarly, other downstream users are wasting a significant amount of time correcting CAD model errors as well.

This presentation will discuss the Model Quality concept and demonstrate how these problems can be easily isolated and identified. It will show how implementing a Model Quality program can slash or eliminate the need for the downstream users to fix problem CAD files. We will detail how CAD/CAM/CAE users at any level can and should begin implementing such a program. While the presentation will provide a solid overview, it will highlight the CAE interests of the audience.

RAPID OPTO-MECHANICAL DESIGN USING PRO/E, MSC/NASTRAN AND CODE V. (Acrobat 683K) #2198, 10 pgs.
Victor J. Wagner, Richard Malnory, and K. Scott. Ellis--Raytheon Missile Systems Company

ABSTRACT: The mechanical design of Optical systems (Opto-Mechanical Design) is typically concerned with minimizing the impact of the mechanical structure and environments on optical performance. Structurally insignificant loads may induce unacceptable motion and/or distortion into the optical elements, which are summed along the optical path resulting in total image blur and error. Optical system designs are therefore extremely sensitive to mounting configurations and structural dynamic characteristics of the mechanical system. A process for efficient design investigation is discussed that provides rapid system and individual optical element error predictions for mechanical system design. Topics include discussions of fundamental Opto-Mechanical design considerations, Pro/E model modification to facilitate automesh techniques, various automesh approaches using MSC/PATRAN and Pro/Engineer, tet4 vs tet10 element performance and accuracy with MSC/NASTRAN, Line Of Sight (LOS) error predictions, and Zernike polynomial calculations for optical surface aberrations using the MSC/OPOLY utility and Code V.

RECENT ADVANCES IN MSC/PATRAN PRE-PROCESSING SOFTWARE ALLOWS MODELING OF COMPLEX AUTOMOTIVE LAMP DESIGNS (Acrobat 618K) #3398, 9 pgs.
William I. Moore, Eric S. Donovan, and Christopher R. Powers-- Delphi Interior and Lighting Systems

ABSTRACT: Advances in automotive lamp designs have resulted in a more compact, aerodynamic packaging and the use of less expensive plastic materials for the lens and housing. The smaller packaging and lower melting point of plastics have increased the need for a predictive tool for simulating the lamp temperature rise under operating conditions. The modeling of lamps requires sophisticated analysis tools incorporating computational fluid dynamics and specular radiation. These tools use a finite element method to solve a system of non-linear equations for velocity, pressure and temperature. In addition to the non-linearity, the complex parabolic shape of the lamp reflector and lens requires very powerful mesh generation capability in order to produce an adequately refined mesh. The lamp modeling is performed in two stages. First the model is generated by importing CAD data from Pro/ENGINEER or Unigraphics into the MSC/PATRAN pre-processor. The surfaces are then meshed with triangular elements which are used as a seed for creating the air volume and lamp solid wall tetrahedral element meshes. The use of the new MSC/PATRAN hybrid tetrahedral mesher has enabled the creation of very complex 3D element meshes to represent fluid volumes with several hundred thousand elements. MSC/PATRAN has become a common pre/post-processor for many analysis codes because of the open CAE environment, advanced meshing capability, ease of applying loads and boundary conditions and effective post-processing capability for displaying results.

DMAP

A DMAP ALTER TO CALCULATE THE CONTRIBUTIONS OF INDIVIDUAL MODES IN A MODAL COMPLEX EIGENVALUE OR FREQUENCY RESPONSE SOLUTION(Acrobat 358K) #1798, 9 pgs.
Ted Rose Manager--MSC

ABSTRACT: In this paper, a DMAP alter is presented which will calculate and print the Contributions of individual modes to a solution at user-selected locations. The alter allows you to chose from several different formats for the output: Magnitude/phase, real/imaginary, projection on solution, fraction of solution, and others.

MDI/ADAMS-MSC/NASTRAN INTEGRATION USING COMPONENT MODE SYNTHESIS (Acrobat 98K) #1998, 10 pgs.
Gisli Ottarson--Mechanical Dynamics Inc.
Greg Moore--The MacNeal-Schwendler Corporation
Diego Minen--Mechanical Dynamics Inc., Italy

ABSTRACT: Improvements continue to be made in the area of MSC/NASTRAN-MDI/ADAMS coupling, with the status of the jointly developed DMAP/translator-based interface described herein. Although the current implementation still relies on a combined DMAP alter and an external utility, the results of this phase of development include a number of enhancements which greatly improve ease-of-use, performance, and results quality. This paper briefly describes the motivation for the current work, outlines improvements made to the component modes-based interface, and concludes with an example of the new interface's use in automotive vehicle design.

Fatigue Analysis

FINITE ELEMENT BASED FATIGUE ANALYSIS (Acrobat 13.3 MB) #1298, 15 pgs.
Dr. NWM Bishop and Alan Caserio--MSC

ABSTRACT: Fatigue analysis procedures for the design of modern structures rely on techniques, which have been developed over the last 100 years or so. The first accepted technique was the S-N or stress-life method generally given credit to the German August Woehler for his systematic tests done on railway axles in the 1870's. Initially these techniques were relatively simple procedures, which compared measured constant amplitude stresses (from prototype tests) with material data from test coupons. These techniques have become progressively more sophisticated with the introduction of strain based techniques to deal with local plasticity effects. Nowadays, variable stress responses can be dealt with. Furthermore, techniques exist to predict how fast a crack will grow through a component, instead of the more limited capability to simply predict the time to failure. Even more recently techniques have been introduced to deal with the occurrence of stresses in more than one principal direction (multi-axial fatigue) and to deal with vibrating structures where responses are predicted as PSD's (Power Spectral Density's) of stress. Even more recently researchers have addressed the requirements for the design of specific components such as spot welds. All of these techniques were developed outside of the Finite Element environment. However, they have now been implanted into many FE based analysis programs, the best known of which is MSCFATIGUE. The FE environment introduces additional considerations relating to how input data is processed and how fatigue life, or damage, results are post processed. This paper will deal with the issues associated with how fatigue techniques can be incorporated into the FE environment. Modern examples of FE based fatigue design will be included.

VIBRATION FATIGUE ANALYSIS IN THE FINITE ELEMENT ENVIRONMENT (Acrobat 4.3 MB) #1398, 15 pgs.
Dr. Neil Bishop and Alan Caserio--MSC

ABSTRACT: Fatigue damage is traditionally determined from time signals of loading, usually in the form of stress or strain. However, there are many design scenarios when the loading, or fatigue damage process, cannot easily be defined using time signals. In these cases the design engineer usually has to use a test based approach to evaluate the fatigue life of his structure or component. Or, alternatively, a frequency based fatigue calculation can be utilized where the loading and response are categorised using Power Spectral Density (PSD) functions.

One very important design problem, which falls into this category, is that of acoustic fatigue. However, there are also many other situations where structures are subjected to a random form of loading such as wing flutter, landing gear runway profiles, engine vibrations and so on. All of these situations can be analysed using new fatigue life estimation techniques now incorporated in MSC/FATIGUE.

The theory of random vibration fatigue has seen a number of important developments over the last fifteen years. The authors have been personally involved in developing new fatigue analysis theories and structural analysis techniques in the frequency domain. More recently this work has focused on the link with Finite Element Analysis (FEA) because of the powerful design opportunities which this creates. The work has found many important practical applications. This paper will provide a state of the art perspective of random vibration fatigue technology. A number of design applications will be presented.

General Stress Analysis

APPLYING VIRTUAL REALITY TECHNOLOGIES TO THE INTERACTIVE STRESS ANALYSIS OF A TRACTOR LIFT ARM (Acrobat 455K) #0198 , 15 pgs.
Michael J. Ryken, and Dr. Judy M. Vance-- Iowa State University

ABSTRACT: The objective of this research is to examine the challenges of applying virtual reality techniques to the interactive stress analysis of a tractor lift arm. NURBS-based free form deformation, finite element analysis, sensitivity analysis, collision detection, and virtual reality are combined to create an interactive environment for designers to view and modify part shape, evaluate the resulting stresses, and check for interference of the new part shape and surrounding parts in real-time. These methods are implemented using a surround screen virtual environment where the part of interest and associated geometry surrounding that part are displayed together using stereo projection to provide a three-dimensional view of the assembly.

DIRECT OR ITERATIVE? A DILEMMA FOR THE USER (Acrobat 33K) #2698, 8 pgs.
Petra Poschmann, Louis Komzsik and Stefan Mayer--The MacNeal-Schwendler Corporation

ABSTRACT: The subject of this paper is the comparison of Direct and Iterative solvers in the Solution of large Finite Element Problems with MSC/NASTRAN. The results of such a comparison vary based on problem type and with new developments in both the direct and iterative solution techniques. This paper gives the current state of this comparison with MSC/NASTRAN V70.5.

Experiences gained in the past show that analysts are hesitant to use the iterative solver because the direct sparse solver has been in MSC/NASTRAN from the beginning, is very robust and has gone through several optimization phases. MSC's direct sparse solver has very low memory requirements, a very efficient out-of-core logic and very good re-ordering techniques.

The iterative solver, on the other hand, was first delivered only early in this decade. It has since been improved significantly by adding more and better preconditioning techniques, the latest one being BIC (Block Incomplete Cholesky) preconditioning which was introduced in V69 . Many clients started to use it for 3-D models and have reported positive results. More recently, in MSC/NASTRAN V70.5 the memory management and spill logic for the BIC preconditioner of the iterative solver have been improved significantly, particularly for jobs where the solution cannot be done completely in-core.

We will briefly discuss the methods used for the direct and iterative solvers in MSC/NASTRAN, the effects of new re-ordering schemes in the direct solver and the effects of the BIC preconditioning technique in the iterative solver. Moreover, we will present performance results for large models involving different types of elements to give guidelines on where the advantages of each solver lie and when is it more beneficial to use one solver over the other. For example, for models built from 2D elements it is always recommended to use the direct solver while for models of 3D elements the iterative solver should be preferred. Other issues like memory and disk space requirements and multiple load cases will also be discussed. The focus of the paper is on linear static analysis.

GLOBAL-TO-LOCAL ANALYSIS WITHOUT USING SUPERELEMENTS (Acrobat 504K) #2598, 13 pgs.
Klaus Otto Schwarzmeier-- Empresa Brasileira de Aeronáutica S/A

ABSTRACT: Detail analysis of a structure in general is a problem at least workful. Frequently this type of analysis requires very refined finite elements meshes being unfeasible to include all regions of interest in an unique model. This work can be simplified when we substitute the unique model by a set of interrelated models. We consider in the methodology presented in this paper, one model called primary model to analyze the global behavior of the structure and some other models, the secondary models, to do the detail analysis of some regions based on the results of the primary model analysis. The technique presented here does not use the Superelements feature of MSC/NASTRAN, neither mesh transitions. Therefore, it can be easy used with MSC/NASTRAN for Windows. The use of this technique by means of MSC/PATRAN will also be discussed.

NONLINEAR SIMULATION OF A LEVER MECHANISM (4.1 MB) #0398, 14 pgs.
Sergio E. Adeff--The MacNeal-Schwendler Corporation

ABSTRACT: Many device designs include shaped lever mechanisms that must function reliably through a variety of load conditions. A lever shape is often optimized to carry out their function with optimal use of the material and processes involved in their fabrication. Levers are present in all types of devices, commonly in computer hard drives, car engines, airplane control mechanisms, medical instruments, et cetera. The design discussed in this paper is a hypothetical yet realistic one. The purpose of this work is to serve as a demonstration and training device for Engineers interested in learning how to create an adequate model and carry out complex calculations involving large displacements and contact between rigid surfaces and a three-dimensional representation of the deformable bodies of two levers and other parts of a mechanism. The model will be available to any interested party in the form of an MSC/PATRAN database [1] with the MSC/ADVANCED FEA preference [2] in the World Wide Web. The paper focuses on one aspect of the more general analysis required for a complete design, namely the calculation of stress and strain distributions, particularly in areas of contact and impact, nonelastic deformations, velocities, and driving and reaction forces under transient conditions. Problems of convergence often faced when doing a nonlinear analysis of this type are also discussed. The design -better understood by looking into figures in the paper- includes four distinctive pieces, designated as hammer, trigger, anvil, and band. Both the hammer and trigger are levers pivoting about fulcrum pins extruded from the anvil. Likewise the hammer and trigger have each an extruded pin to which the band is tightly attached pulling the two pieces together. The disposition is such that when the trigger is actuated, the hyperelastic band first accumulates strain energy and the hammer remains in place, and then the band suddenly transfers the stored strain energy to the hammer, which is accelerated and then impacts a protrusion of the anvil. The hammer cames a seal, which impacts a stamp lying on the anvil. The stamp undergoes plastic deformation as a result of the impact.

A PERFORMANCE COMPARISON OF MSC/NASTRAN V68.2 THROUGH V70.5 ACROSS MULTIPLE HARDWARE PLATFORMS (Acrobat 228K) #2798, 15 pgs.
Joe Griffin--The MacNeal-Schwendler Corporation

ABSTRACT: There have been enormous advances in both hardware and software technology in recent years. This paper illustrates MSC/NASTRAN performance using several types of analyses with several versions of MSC/NASTRAN on multiple hardware platforms. The purpose of this paper is to inform users of performance enhancements, which are a result of these advances in technology.

Optimization

CAD BASED OPTIMIZATION (Acrobat 98 K) #0498, 10 pgs.
Celso Barcelos-- MacNeal-Schwendler Corporation

ABSTRACT: In one form or the other one of the primary goals of simulation technology over the years has been to optimize designs. On the whole this has been a manual process involving the generation of multiple mathematical models which have been used to validate a given design, and also to compare different configurations of a design. Although the use of simulation techniques has proven to be an invaluable part of the engineering design cycle they has not yet had the impact everyone desires. In order to help engineers to shorten the design cycle optimization software has been added to existing packages. Even with these new technologies we are still not seeing the kinds of efficiencies that design firms have hoped for. The reasons for why simulation applications, and FEA in particular, have not had their fullest impact to obtain optimized designs are long and varied. Some of these factors include:

  • FEA has been hard to use and therefore has been relegated to just a handful of specialist rather than mainstream design engineers.
  • Optimization technology itself has been slow to mature.
  • The CAD software used for design, and FEA software used for simulation have been stand-alone systems which simply don't talk to each other very well.

This paper describes a system which marries geometric construction tools, simulation software, along with topology and shape optimization technologies which can be utilized by engineers early in the design cycle to reduce the time needed to bring new products to market. By integrating these formerly disparate functions under one umbrella we have taken a giant step forward to achieve efficiencies which were unthinkable just a few years ago.

DESIGN OPTIMIZATION USING HYPERSIZER (Acrobat 5.6MB) #0698, 12 pgs
Craig Collier, Phil Yarrington, and Mark Pickenheim Collier--Research Corporation

ABSTRACT: This paper identifies an existing commercial solution that MSC users can benefit from for automated stress analysis and sizing. The HyperSizer software is mathematically coupled with MSC/NASTRAN to provide an integrated solution for quick and accurate design optimization. Though specifically developed for the aerospace industry, the approach and methods apply to any industry. A reusable launch vehicle, which contains 7 assemblies, 21 optimization groups, and 203 structural components is used as an example. MSC/NASTRAN is used as the loads model and the entire plane is optimized using HyperSizer's analysis methods that range from closed form, traditional hand calculations repeated every day in industry, to more advanced panel buckling algorithms. Margin-of-safety reporting for every possible failure provides the engineer with a powerful insight into the structural problem. The engineer is able to provide 'real-world' expertise in the optimization process by interacting with HyperSizer for designs on the fly.

FE-OPTIM AND MSC/NASTRAN FOR A FREQUENCY RESPONSE OPTIMIZATION (Acrobat 291K) #0798, 14 pgs.
Dr. Stefan Döemöek and Andreas von Mach--P+Z Engineering GmbH
Dr. Jürgen Merk--AUDI AG

ABSTRACT: FE-OPTIM, a software tool developed by P+Z Engineering GmbH, supports the MSC/NASTRAN optimization (Solution 200) in all its key features. The use and the benefits of FE-OPTIM, combined with MSC/NASTRAN SOL 200, is demonstrated on an example of an AUDI project.

HANDLING OF WELDS IN SHAPE VECTORS GENERATION FOR FINITE ELEMENT SHAPE OPTIMIZATION - A CASE STUDY (Acrobat 455K) #2498, 6 pgs.
Murali M.R. Krishna--DANA Corporation

ABSTRACT: Design analysts, who work with finite element shape optimization, face a daunting task of handling welds. When the designer wants to find the optimum width of the leg of a bracket, which is welded to a base rail, the analyst has to remove the old welds, remodel and re-create new welds after extension of the bracket, and iterate. This method is not suitable for shape optimization. A numerical interpolation method based on 'Autodv', has been recommended to handle welds without remodeling. This method is very effective for finite element shape optimization. A case study has been given to illustrate the method using MSC/NASTRAN.

LINEAR CORRECTION OF BUCKELED PANELS USING SOL 200 (Acrobat 153K) #0998, 20 pgs.
Michael C Kobold--Northrop Grumman Corporation

ABSTRACT: A method to account for the buckling of skin panels on stiffened shell structures using MSC/NASTRAN SOL 200 linear static optimization is shown. This builds on previous work, shows conservatism of the classical manual methods, and introduces several ways to tackle the problem. The Finite Element Analysis (FEA) involves the comparison of the use of Design Optimization (SOL 200) for effective width and thickness changes, to example A20.4 of Bruhn's text 1 . The Finite Element model uses a small fuselage section with a height of 50 inches, width of 30 inches. The foundation work for crippling strength calculation software is provided in an Appendix. This work is applicable to curved shell buckling issues in its use of empirical data available in the literature. This method's best implementation will be with p-elements due to their geometry information. The method has application to general stiffened curved panel structural analysis.

MSC/CONSTRUCT - FEATURES AND CAPABILITIES (Acrobat 2.3MB) #0898, 18 pgs.
Dr. Hans Sippel--MSC, Munich

ABSTRACT: For design engineers and analysts MSC/CONSTRUCT1) provides an exceptionally fast and easy-to-use, conceptional design tool consisting of two options:

  • MSC/CONSTRUCT TOPOLOGY is the topology optimization option, which distributes material within a design space envelope based on the optimum load paths.
  • MSC/CONSTRUCT SHAPE is the non-parametric shape optimization option, which homogenizes the stress distribution (Fully Stressed Design).

Both of these options are FEM-based and use an efficient optimality criteria technique. In the optimization cycle MSC/NASTRAN is used as the analysis engine. This guarantees reliable results and highest performance.

MSC/CONSTRUCT V2.5 was released in Q3/98. Major highlights are:

1. A graphical user interface within MSC/PATRAN
2. A restart option
3. High performance improvements which significantly increase the throughput
4. An automatic shape basis vector generation for MSC/NASTRAN's SOL 200 by MSC/CONSTRUCT

Especially items 3. and 4. will be presented by customers' real life examples.

USAGE OF OPTIMUM USAGE OF OPTIMIZATION TOOLS IN THE DESIGN PROCESS AT BMW (Acrobat 33 K) #0598, 10 pgs.
Ingo Raasch--BMW AG, Munich

ABSTRACT: The usage of optimization tools in structural mechanics has a long history at BMW, and it is very much connected with MSC/NASTRAN. Sizing is a standard procedure in body design with constraints on static and dynamic response. Shape optimization with MSC/NASTRAN was an initial success. However, at present it is performed most often with other programs owing to the ease-of-use and integration within CAD systems. The definition of shape vectors is still time consuming in both MSC/NASTRAN and other programs. Optimality-criteria methods such as MSC/CONSTRUCT SHAPE improved the ease-of-use, but with a sacrifice in the generality of the objective and constraints definitions. However, a combination of optimality criteria, mathematical optimization methods, and automatic shape generation has proven to be a more general and efficient approach.

Topology optimization is finally being used in the concept design phase. The definition of the design space can be accelerated tremendously by using the VOXEL technique of CAD systems. In this technique, a given volume is filled with cubes of equal size, in order to estimate the volume or detect component collisions. These cubes are directly used in the finite element design space definition.

Concept design relies heavily on beam/shell models with beam cross sections as design variables. However, given the short time frame for the concept design phase, optimization is still hampered by the lack of pre/processing tools for the design model definition and post processing of results, as well as the necessity for heavy computing resources.

PCL

CUSTOMIZATION OF WING ANALYSIS (Acrobat 33K) #3698, 7 pgs.
Wang Linjiang--Nanjing University of Aeronautics and Astronautics, PR China
Matthias Haupt--TU Braunschweig, Germany

ABSTRACT: This article is concerned about the customization of creating a FEM model of a wing structure. The row and column method is used to number the structure parts(ribs, spars, skins), then the property parameters of all parts can be respectively inputted using the spreadsheet in which data can be inputted easily and correctly. A PCL(MSC/PATRAN Command Language under MSC/PATRAN 6.0) code is developed for the customization from constructing airfoil curves to creating the entire wing FEM model. A zigzag wing is demonstrated to verify the code. At last a VFW614 wing is analyzed from creating airfoil curves to the show of stresses that are calculated using MSC/NASTRAN 68. The results shows that this customization is very effective and efficient, it makes such a difficult work of creating a wing FEN model become much easier. This method can likewise be used to fuselage and other complicated structures.

ENVELOPING RESULTS OF MULTIPLE LOAD CASES (Acrobat 65K) #3498, 10 pgs.
Victor Genberg--Eastman Kodak Company
Justin Vianese--The MacNeal-Schwendler Corporation

ABSTRACT: Many structures such as those used in the aerospace and the automotive industry are subjected to multiple load conditions. Software has been developed to scale, combine, and sort stresses, forces, and displacements from a few unit load cases. The procedure saves creating and running many load cases, requires much less plotting, and prevents errors of omission. A launch load event of 128 combinations can be analyzed from 7 unit load cases combined into a single plot. This technology is now available as MSC/PATRAN shareware.

INTEGRATION OF "ANLEET" AND "ANVECT" PROGRAMS IN MSC/PATRAN ENVIRONMENT (Acrobat 130K) #3298, 10 pgs.
Alejandro Andueza--Sercon Consulting Services
Claudio dos Santos Amaral and Alvaro Maia --Petrobrás/Cenpes, Rio de Janeiro

ABSTRACT: Sercon is a consulting company committed to offering Finite Element design solutions to the market. We have a long-term experience in the oilfield market, offering FEA analysis and design of subsea equipment. Most recently, as part of a close relationship between Sercon and MSC Brazilian office, we have also been offering customized solutions to MSC clients.

Petarobrás is one of the biggest oil companies in the world with an annual revenue of over 20 billion dollars. It is currently committed to developing technology to extract oil from deep-water. Petrobras has already found oil fields at depths of over 8000 ft of water.

"Anleet" and "Anvect" programs are custom tools developed by Petrobras to help it in the design of special piles and anchors which are used as fixed points of the anchoring lines of floating production units such as sub-submersibles and FPSO's. These programs have specific features that MSC/PATRAN is not able to pre-process in its commercial version. Prior to the development of this work, Petrobrás took too much time to generate the input deck for "Anleet" and "Anvect" programs using external programming in order to modify MSC/PATRAN neutral file.

The purpose of this paper is to show the integration process developed by Sercon to attend Petrobrás's requirements using MSC/PATRAN open architecture. As part of the integration process we have developed specific mesh generators for 3D contact elements and 3D infinite elements.

We have also developed a parametric model to help Petrobrás to speed up the optimization process of the anchor design.

ROLE OF A CUSTOMIZED MSC/PATRAN INTERFACE IN LOWERING COSTS AND "TIME TO MARKET"(Acrobat 163K) #2898, 10 pgs.
Anthony J. Scott and Donald A. Traub Owens-Brockway

ABSTRACT: In today's competitive market, part cost and timely delivery are the main driving forces. Finite element analysis (FEA) software coupled with custom PCL can enable companies to rapidly verify how geometry changes in a plastic container design will affect its mechanical properties. Owens-Brockway (OB) is in the plastic container market. "Time to market" is very important to its customers. The faster OB can get a new functional product into production, the better chance it has of getting ahead of its competition. One of the biggest concerns in the design of a new container is top-load capability. OB, through the use of a custom FEA tool, can determine the best design of a plastic bottle to maximize the top-load capacity. This will be accomplished by using finite element analysis software that has been tailored to reduce the set-up time. FEA has the reputation for being an analyst's tool, as a consequence many manufacturing companies prefer to construct prototype parts, perform destructive test, and modify the design based on the results. Major cost reductions can be realized by eliminating the need for such a prototyping approach.

Test/Analysis Correlation

DRIVESHAFT SEAL BOOT FINITE ELEMENT ANALYSIS (Acrobat 98K) #3998, 10 pgs.
Leandro Jaskulski, Leônidas Coutinho, César Franck, and Rubens Gehlen--ATH - Albarus Transmissões Homocinéticas ltda.

This study registers a finite element analysis of a seal boot used in constant velocity driveshafts, that was performed in the MSC/NASTRAN software for Windows NT 4.0 in a Personal Computer. By this analysis the structure’s behavior was studied in its work life before construction of the actual prototype.
Analysis was made in existing seal rubber boot, showing good accuracy level when compared with actual part displacement test results. At first, critical joint motions were selected to identify the constrains and symmetric plans. The hyperelastic material was approached to an elastic material in this first step to apply in a plate element model of the part. Then the results of general part behavior, like displacements, and contacts were examined and contrasted with laboratory test reports of the real part.
Prototype development time can be saved in the design phase since the part can be improved by this theoretical prediction tool. Failure points can be predicted by the analysis saving resources such as developing production tools, making prototypes and testing them to finally detect the items that have to be improved.

STRUCTURAL DESIGN OF A GUIDING PLATE IN THE PLASTIC REGION (Acrobat 585K) #2998, 15 pgs.
Fábio L. Amaral dos Anjos, Romulo R. Ripoli, and Marcos Antonio Argentino--debis humaitá IT Sevices Latin America

ABSTRACT: In order to study the mounting stresses of a guiding plate which holds the leaf spring suspension of a bus, a structural finite element analysis, with MSC/NASTRAN v.70, was conducted. Plasticity and non-linear geometric effects was considered on the model. The mounting load was evaluated and experimentaly measured. Results from the finite element model of the guiding plate were compared to experimental ones. A new geometrical configuration for the part was suggested and analized. The aim was to minimize plastic deformation of the material and to reduce the mounting stresses.

THE USE OF MSC/NASTRAN SOL200 IN A TEST-ANALYSIS INTEGRATION PROCESS APPLIED TO CONNECTION-WELD MODELLING. (Acrobat 2.6MB) #2298, 9 pgs.
Tom Van Langenhove--LMS International, Belgium
Dennis Turner-- Matra Bae Dynamics

ABSTRACT: When building finite element models, a lot of simplifying assumptions and estimates have to be made. Idealisation, discretisation and parameter evaluation are all possible error sources. If these models have to be used in lifetime estimations, optimisation processes or system synthesis computations, they have to be a valid representation of reality. In this paper it is discussed how MSC/NASTRAN sol200 is used in the process of validation and verification of dynamic finite element models. This paper focuses on a frame support. It shows the different steps taken at both the experimental and the analytical side and describes the complete process based on the 'actual' application problems. The main features of this support frame are the welded joints, the connections between solid and shell elements and the modeling of a solid base by means of shell elements with a certain thickness. Using powerful functionality's such as correlation, sensitivity analysis and physical as well as proportional updating, a well-correlated FE model is obtained and the welded joints and the thickness of the base are identified as 'hot spots'.

USING MSC/MVISION TO SIMPLIFY AND EXPEDITE ACCESS TO AND ANALYSIS OF BENCHMARK DATA (Acrobat 121K) #1098, 7 pgs.
Kirsten Husak--Raytheon Systems Waco

ABSTRACT: MSC/MVISION is an extremely flexible database application which can be used to manage any type of information.

At Raytheon, Waco, MSC/MVISION is being developed to store data from a major benchmark. A schema is in development which will enable retrieval of results from any benchmark, performed on any platform, testing any new software package. When complete, queries will be possible over all data acquired during a benchmark, allowing vastly improved assimilation and analysis.

Thermal Analysis

NUMERICAL MODELLING OF LIGHT TRANSMISSION IN A TEMPERATURE AND STRESS SENSITIVE OPTICAL ELEMENT (Acrobat 228K) #3198, 12 pgs.
Daniel Wormser, Dr. Yoram Liran, and Yonatan Cohen--Electrooptics Industries Ltd.,
Dr. Joseph Roitfarb, Dr. Vladimir Kaminsky, and Dr. Shlomo Yanetz--Bar-Ilan University

ABSTRACT: The subject of this research is numerical modelling of single pass light transmission through a general optical component subjected to thermal and structural loads. The light transmission is calculated numerically for an FE model considering both the thermal effect on the refractive index, and the structural distortions of the optical component. The thermal and the structural analyses of the optical component model are computed using the MSC/NASTRAN FE software. The results of the MSC/NASTRAN FE analyses are used as input to the light transmission analysis 'IMU-POST' .
The output light beam is analysed with respect to wave-front deviation and distortion.

USE OF FINITE ELEMENT MODEL AND TEMPERATURE MEASUREMENTS FOR REAL TIME CONTROL OF ACTIVE SURFACE AND POINTING OF A 50 M RADIO TELESCOPE (Acrobat 65K) #3598 12 pgs.
Frank W. Kan and Rajesh S. Rao--Simpson Gumpertz & Heger Inc.

ABSTRACT: The Large Millimeter Telescope (LMT) is a 50 m diameter radio telescope with an actively controlled segmented surface to be used for astronomy at millimeter wave lengths. The specifications call for a surface accuracy of 70 micrometers RMS and a pointing accuracy of 0.7 arcseconds RMS. This paper evaluates a proposed approach for computing and correcting in real time the surface deformations of the primary reflector and the pointing errors of the telescope due to thermal deformations using a finite element model and temperature measurements throughout the telescope structure.