MSC 1999 Aerospace Users' Conference Proceedings


The conference proceedings for the 1999 MSC Aerospace Users' Conference are now available on-line in Adobe Acrobat PDF format. (The Adobe Acrobat Reader software is available for free download from Adobe's web site at www.adobe.com.)  When printed, these PDF files will produce a better quality image than the one shown on your computer screen. All papers have been categorized by topic.
 

Categories

Aeroelasticity

AEROELASTIC ANALYSES IN "PZL-MIELIC" USING MSC/NASTRAN(Acrobat 293K) #2199, 13 pgs
Wojciech Chajec--Aircraft Factory "PZL-MIELEC" Ltd.

ABSTRACT: Presented here is implementation of MSC/NASTRAN system in aerolastic computation practice in "PZL-Mielec". This computation system is compared with our own old flutter calculation programs. Discussed are advantages and also difficulties caused overcoming of old habits and the fact that MSC/NASTRAN is an universal system not only for flutter calculation. PC programs which were created specifically to overcome the difficulties are presented additionally. A few interesting results of calculations are also showed.

Contents
1. Short view on flutter calculation methods in "PZL-Mielec" before MSC/NASTRAN based on calculated (beam-like structural calculation model) or in GVT measured modes.
2. Implementation of MSC/NASTRAN system.
3. Description of additional programs for PC - useful for aeroelastic calculation in MSC/NASTRAN, prepared in "PZL-Mielec"

· programs for natural mode and flutter mode animation and drawing
· program for drawing and sorting flutter calculation results: g(V), f(V)
· graphic preprocessor for aerodynamic data generation and static pressure distribution drawing (for static aeroelasticity calculation)
· some modification of propf.for program (in propa.v68 - alter) for aerodynamic forces in whirl-flutter calculation
4. Examples of aeroelastic calculation in "PZL-Mielec" and problems
5. Conclusions
AN ENHANCED CORRECTION FACTOR TECHNIQUE FOR AERODYNAMIC INFLUENCE COEFFICIENT METHODS
(Acrobat 488K) #2299, 12 pgs
Ioan Jadic, Dayton Hartley and Jagannath Girl--Raytheon Aircraft Company, Kansas
ABSTRACT: The present Enhanced Correction Factor Technique (ECFT) is intended to provide an improved solution to the classical problem of correcting the Aerodynamic Influence Coefficients (AIC) formulation produced by panel methods, such as the Doublet Lattice Method (DLM). In the case of MSC/NASTRAN aeroelastic analysis methods, provisions are made for inclusion of correction matrices which premultiply the AIC matrix in order to provide a level of accuracy of the aerodynamic forces consistent with experimental and/or CFD data. Classical techniques use a diagonal correction matrix allowing for limited correction capabilities: typically, one mode. By contrast, the present ECFT uses a full correction matrix that can handle multiple modes simultaneously, allowing a complete correction capability including any interference effects. Further, it is possible to define by means of ECFT several correction matrices that tackle nonlinearities for a given Mach number.

Several comparisons are presented which cover a wide range of application cases. The results obtained with ECFT are shown to match the input data.

BALANCED CONTINUOUS TURBULENCE GUST LOADS USING SOLUTION 146(Acrobat 195K) #2099, 13 pgs
James E. Locke, Sr. Technical Specialist--Raytheon Aircraft Company
ABSTRACT: This paper describes and illustrates a method to obtain balanced (time-correlated) continuous turbulence gust loads using MSC/NASTRAN Solution Sequence 146 (SOL 146). Continuous atmospheric turbulence is modeled in the frequency domain as a power spectral density (PSD) function using the von Karman gust PSD. SOL 146 is used to obtain the complex frequency response for each load quantity. Balanced loads are determined using the equations of random process theory. Maximized load quantities correspond to RMS values determined from response PSD functions. Balanced loads for each maximized load correspond to scaled cross-correlation functions. Results are presented for a typical gust load condition.
COUPLED AEROELASTIC ANALYSIS OF A  FREE FLIGHT ROCKET(Acrobat 228K) #2399, 11pgs.
D.S. Livshits, S. Yaniv--IMI - Israel Military Industries
M. Karpel--Technion - Israel Institute of Technology
ABSTRACT: Aeroelastic analysis of rockets is an essential part of their design procedure. In most cases, the analysis is limited to calculation of the divergence velocity, sometimes leading to unrealistic prediction of the rocket response. The coupled dynamic aeroelastic analysis approach is established to allow for the consideration of coupling effects between the rocket spin, its imperfection parameters and the airflow. The approach is based on integrated dynamic aeroelastic/CFD modeling methodology
Aero Engines

DYNAMIC ANALYSIS OF FLEXIBLE TURBO-ROTOR SYSTEM USING SUPER-ELEMENTS
(Acrobat 130K) #1799, 14pgs.
A. Surial and Dr. A. Kaushal--Rolls Royce, Montreal
ABSTRACT:The approach presented in this paper will give an overview on the dynamic analysis of gas turbine engines. It will help a user to prepare an input file for MSC/NASTRAN in order to perform the critical speed (SOL 107) and forced response analysis (unbalance response — SOL 108) of any size rotating structure(s), taking into account gyroscopic effects using MSC/NASTRAN DMAP, ridgyroa.v705.
SNECMA BLADE AND DISK MESHING METHODOLOGY(Acrobat 325K ) #1699, 10pgs.
Antoine Soeiro--MacNeal Schwendler, France
ABSTRACT:This paper will describe a consulting project that MSC France did for Snecma. This project was called time cycle reduction. We aimed at increasing the productivity of Snecma's Design Office by defining the most accurate methodology for meshing a compressor blade and disk using MSC/PATRAN.

Throughout this presentation the detailed process will be developed to explain how the time reduction was obtained.

According to what has already been done, both Snecma and MSC have great hope to enhance our first results by using MSC new tools.

STRUCTURE SIMULATION AND BLADE DESIGN OF AN AIRCRAFT ENGINE(Acrobat 1.3MB) #1899, 12 pgs.
André Ollivier--SNECMA
ABSTRACT:Structural analysis have progressed at a level such that they are now increasingly used all days in activities of mechanical engineering

Since 25 years at SNECMA, analyses have for main objective to provide in both detail and overall a knowledge of the behaviour and damage of the part, they are an help with the decision in design conception via optimization.

We are currently in a period of utilization of more and more simulations , what allows to reduce significantly the number of tests. Researches allow to develop tools simulating the behavior increasingly precisely.

These simulations have become of necessary tools, to reduce costs, to reduce cycles, to design robust. Take into account very early manufacture constraints in simulations, improved the simultaneous engineering.

It is demonstrated here after that the large use of simulation during the period of life of the product, will allow to improve them, and to answer as quickly as possible to quality and reliability needs of the companies.

Finally, it is necessary to insist on the inter-operability of tools of simulation, centered on a numerical geometrical model. This inter - operability has to accompany the concept of extended enterprise and the world cooperation necessity. These are the keys of the success of industrial products design for the next century.

VALIDATION AND UPDATING OF AN AERO ENGINE FINITE ELEMENT MODEL BASED ON STATIC STIFFNESS TESTING (Acrobat 65 K) #1999, 8 pgs.
E. Dascotte --Dynamic Design Solutions
A. Schönrock--CargoLifter Development GmbH
ABSTRACT: Today's aerospace industry uses finite element analysis in a huge variety of applications in order to optimize structures and processes before hardware is procured. Efficiencies can be enhanced and margins are reduced because external loads and the structural properties are identified with higher confidence. The accuracy of finite element analysis predictions therefore becomes more and more important and directly influences the competitiveness of the product on the market.

In particular, accurate shell element models are difficult to generate because of the inability to account for fillet radii and problems with coupling of the in-plane rotational stiffness. Another common uncertainty is the accuracy of modeling shell structure bolted flanges and especially their behaviour under large loads. These features are widely used for structural finite element modeling within the aeronautic industry.

Although modal testing has proved to provide valuable reference data for FE model validation and updating, static stiffness tests have the advantage to allow the application of large forces. In addition, static deformations are independent of the mass parameter.

To process static test data and MSC/NASTRAN analysis results and perform correlation analysis and FE model updating, appropriate methods were developed and implemented into the existing FEMtools software. This paper describes the approach and gives reference to a successful application.
 

Applications

THE COMBINATION OF MECHANICAL SYSTEM SIMULATION AND FINITE ELEMENT ANALYSIS SOFTWARE TO MODEL STRUCTURAL FAILURE IN AN AIRCRAFT ACCIDENT INVESTIGATION(Acrobat 943 K) #2699, 15 pgs.
Greg Savoni--Boeing Long Beach
J. McConville-- Mechanical Dynamics
ABSTRACT: The MSC/NASTRAN finite element analysis (FEA) code is used in conjunction with the ADAMS mechanical system simulation (MSS) program to simulate the structural behavior of the airframe of a commercial aircraft maneuvered beyond its design limits during a landing. FEA-generated linear elastic structures are subjected to non-linear boundary conditions in the MSS analysis to simulate the initial structural failure of the airframe. The analysis results are compared with crash site evidence and subsequent, independent engineering analysis.
THE DEVELOPMENT AND USE OF A MATERIALS DATABASE FOR PRODUCT DESIGN AND COMPONENT LIFING.(Acrobat 228K) #0199, 13pgs.
Barry J Piearcey, Chris K Bullough, Martin Hughes and Steven J Moss--ALSTOM Energy Technology Centre
ABSTRACT: Tremendous progress has been achieved in the application of finite element analysis techniques for the modelling of the behaviour of components and structures but the success of application is often limited by the availability of appropriate materials design data. Even when data are available, usually from published sources, some of the supporting metadata is often missing and validation of the design data is not possible. Even well planned characterisation of materials properties through well executed testing programmes lose their value as details of the test parameters and materials are inadequately recorded; and ad-hoc statistical assessment methods obscure the true minimum properties of a material.

This paper describes the development and structure of an MSC/MVISION materials database which is designed to store test and design data. Metadata has been defined to describe each material product and property precisely, standard methods of data analysis provide validated design data and each datum is allotted a quality value. Examples are included which illustrate how the data are used for statistical process control, thermal analysis, stress analysis and the prediction of component life using a continuum damage approach.

The similarity in the technologies used for these disparate activities is counterbalanced by the lack of material property data of sufficient quality. This situation is recognised world-wide as is the inability of any single company to justify adequate resource to correct it. It is concluded that the high cost of producing high quality material product data by independent testing calls for more facilities for the assessment, reporting and exchange of data within MSC/MVISION and highlights the need to agree an international schema and glossary of terms for data exchange.

THE NEW EXTERNAL SUPERELEMENTS IN MSC/NASTRAN AND A DMAP ALTER TO CREATE AND USE OTM
(Acrobat 325 K) #2499, 17 pgs.
Ted Rose--The MacNeal-Schwendler Corporation
 ABSTRACT: It often seems to be several years after the introduction of a new feature before it gains recognition among the user community. This paper is intended to provide an introduction to the new external superelement features introduced in V69 and also provide a DMAP alter which allows the creation and usage of OTM for them, allowing the creation and usage of "deliverable" models.
MSC/FLIGHT LOADS AND DYNAMICS-VERSION 1(Acrobat 358 K) #0299, 10 pgs.
Greg Sikes and Douglas J. Neill--The MacNeal-Schwendler Corporation
ABSTRACT: MSC has been actively developing solutions to the challenges faced by our customers inthe 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.

MSC/FlightLoads and Dynamics Version 1 supports static aeroelasticity (steady state
external loads). This paper will present the current state of the technology within
MSC/FlightLoads and Dynamics Version 1.

USING MSC/MVISION TO COMPARE MSC/NASTRAN RESULTS WITH FLIGHT TEST DATA
(Acrobat 488K) #2599, 20 pgs.
Kirsten Husak--Raytheon Systems
ABSTRACT:At Raytheon Systems Company in Waco, Texas, a MSC/MVISION database has been developed which allows the comparison of flight test data with MSC/NASTRAN results output. A model can be opened in MSC/PATRAN, and strain gauge results generated during a test flight viewed directly on the model. The MSC/NASTRAN strain output can be applied to the model and contrasted with test flight strains in the MSC/PATRAN graphical user interface. If the results are reconciled within a predetermined degree of tolerance, it will then be assumed that the model is accurate. A model predicting the behavior of the aircraft after it has been modified can then be assumed to be accurate also. After the aircraft has been modified, more flight test data will be collected, which can then be compared with the post-modification
predictions to aid in support of FAA certification of the modified aircraft. MSC/MVISION will provide a user-transparent interface between MSC/PATRAN and the raw flight test data, allowing engineers to view the accuracy of their models with real-time strain measurements within the MSC/PATRAN graphical environment. Because Raytheon Waco specializes in aircraft modifications, the concentration in this project has been on the comparison of flight test data with airframe finite element models, but the application of this methodology for comparison of strains with models can be used in any industry which employs modeling and testing procedures.
MSC/DYTRAN

CRASH SIMULATION OF A 1/5-SCALE MODEL COMPOSITE FUSELAGE CONCEPT
(Acrobat 1.2MB) #0399, 14 pgs.
Karen E. Jackson and Edwin L. Fasanella--U.S. Army Research Laboratory, Vehicle Technology Center
Sotiris Kellas--MRJ Technology Solutions
ABSTRACT: This paper describes the MSC/DYTRAN crash simulation of a 1/5-scale model composite fuselage concept, which was developed to satisfy structural and flight loads requirements and to satisfy design goals for improved crashworthiness. The fuselage consists of a relatively rigid upper section which forms the passenger cabin, a stiff structural floor, and an energy absorbing subfloor which is designed to limit impact forces during a crash event. The impact design requirement for the scale model fuselage is to achieve and maintain a 125-g floor-level acceleration for a 31 ft/s vertical impact onto a rigid surface. This impact requirement corresponds to a 25-g floor-level acceleration for a geometrically-similar full-scale fuselage section. To demonstrate compliance with the impact design requirement, the scale model fuselage section was impacted at 31 ft/s vertical velocity onto a rigid surface. The experimental data demonstrate that the fuselage section with a foam-filled subfloor configuration satisfied the impact design requirement. In addition, a second drop test was performed with a 15°-roll impact attitude, which demonstrated that the fuselage concept maintained good energy absorption behavior for an off-axis impact condition. As an aid in the evaluation process, a detailed three-dimensional finite element model of the 1/5-scale model fuselage section was developed using MSC/DYTRAN. Good correlation was obtained between the experimental data and the MSC/DYTRAN analytical results for both impact conditions.

HTML- AND VRML-BASED RESULTS REPORTING FOR MSC/DYTRAN AND MSC/SuperForge
(Acrobat 553K ) #4699, 10 pgs.
Darin Mckinnis and Arjaan Buijk--The MacNeal-Schwendler Corporation
ABSTRACT:MSC/DYTRAN is a general purpose 3D, transient non-linear explicit finite-element and finite-volume solver. Result inspection for MSC/DYTRAN models is difficult because of the large variety of problems and the fact that models may include large deformations, failed elements, fluids, fluid-structure interaction, and fluid free-surfaces. The amount of data generated by an MSC/DYTRAN calculation can be over whelming, especially for the novice user.

Traditional results inspection methods use ASCII based output files for summaries and error messages, and the most common visualization method is to use powerful post-processing software tools such as MSC/PATRAN to view the MSC/DYTRAN results stored in binary results files.
 

A new method of results inspection will be introduced. MSC/DYTRAN will automatically generate an HTML and VRML based report, which provides access to the results in a structured, fast and easy way. The results are web-based, and can thus be shared directly with others.
SMALL DEBRIS IMPACT SIMULATION USING MSC/DYTRAN(Acrobat 3.2 MB) #4599, 15 pgs.
Franco Olmi and Kennedy Diniz do Nascimento--EMBRAER
ABSTRACT:The problem of rotor blade fragment impact against an airplane fuselage (representing the "Small Debris" effect, due to rotor burst) has been investigated. The simulations were performed using the MSC/DYTRAN software, taking into account some different approaches, such the influence of the finite elements modeling (comparison between solid and shell elements) as well as the material behavior (involving characteristics like constitutive law, strain rate effects and failure modes). Finally, to corroborate the analysis, the numerical results were compared with experimental data.
MSC/FATIGUE

SOLDER JOINT RELIABILITY IN PATRIOT MISSLE ELECTRONIC COMPONENTS USING MSC/FATIGUE
(Acrobat 228 K) # 4799K, 10pgs.
Martin E. Bowitz--Boeing North American, Inc.
Alan K. Caserio--The MacNeal-Scwendler Corporation

ABSTRACT:The reliability, or fatigue life, of solder joints is investigated in the Patriot Advanced Capability (PAC-3) missile for various electronic components using MSC/FATIGUE. Frequency response and random vibration analysis is performed using MSC/NASTRAN to extract transfer functions due to a 1G acceleration, and RMS stress levels. The suspect joints are modeled using 8 noded brick elements. Acceleration input load PSDs are defined based on measured vibration test and flight worthiness levels. Stress response PSDs are extracted to determine fatigue lives based on S-N methods. The calculated fatigue lives give confidence that the troublesome solder joints will not only endure the various qualification test, but that there will be enough remaining life to survive actual flight.
MSC/NASTRAN Applications

ANALYSIS AND TEST OF GUN BLAST RESISTANT COMPOSITE STRUCTURE(Acrobat 1.0MB) #2799, 11pgs.
Dennis K. McCarthy--The Boeing Company
ABSTRACT:The lower skins on the Extended Forward Avionics Bay (EFAB) on the AH-64D Apache are exposed to muzzle blast effects from a belly mounted 30 mm chain gun. These composite skins must be sufficiently strong to withstand blast pressure at a minimum weight. Analytical methods presented predict behavior of structure subject to gun muzzle blast. This resulted in a weight-optimized, blast-resistant EFAB design which was fabricated and attached to an aircraft. The chain gun was fired near these skins during hover and forward flight without structural damage. Strain data collected during gun fire verified the analytical method.


AN EFFICIENT AND EXACT SOLUTION FOR RANDOM VIBRATION ANALYSIS USING MSC/NASTRAN PART II: GENERAL RANDOM SPECTRUM(Acrobat 1.1MB) #3299, 17 pgs
E. de la Fuente and J.San Millán--Instituto Nacional de Tecnica Aeroespacial

ABSTRACT: A new method for performing RANDOM vibration analysis within MSC/NASTRAN is presented in this paper. The method is a direct application of a well known result of Linear Systems Theory, and allows computation of RMS values of any number of structural outputs: displacements, stresses, element forces, accelarations, etc. These results can be postprocessed as if they were originated in a conventional static analysis (in colour plots for instance). The method is implemented within MSC/NASTRAN by means of a DMAP Alter, that is carefully described in the paper. The results of this DMAP are compared with those given by standard RANDOM solution of MSC/NASTRAN, in terms of accuracy, CPU time, and calculation capability, showing clear advantages of the presented method. Finally, extensions of the method are outlined.


COMPONENT MODE SYNTHESIS OF STRUCTURES WITH GEOMETRIC STIFFENING IN MSC/NASTRAN
(Acrobat 130K) #3199, 26 pgs.
Tarun Ghosh--Boeing North American, Inc.

ABSTRACT: Implementation of modal synthesis in MSC/NASTRAN is usually done using structural solution sequence based Direct Matrix Abstraction Programs, DMAPs. However, modal synthesis in MSC/NASTRAN without using structural solution based DMAPs is possible. But either method is tailored towards supporting components that have no non-linearity. Certain components, such as the solar arrays of the space station, exhibit non-linear behavior in the form of geometric stiffening. For structures with such components, the standard method of modal synthesis does not work. Special DMAPs need to be developed for these components. Realizing that the only difference between components with no geometric stiffening and those with geometric stiffening is in the method of obtaining the stiffness matrix, a simple solution is provided in this paper. The solution is to use the procedure for modal synthesis for components with no geometric stiffening by replacing the stiffness matrix with the one obtained from geometric stiffening. This approach, along with the recommended check runs, has been shown to work successfully in this paper. The method is also shown to be extremely efficient.
DYNAMIC SIMULATION OF A LARGE DEPLOYABLE SPACE STRUCTURE WITH PINNED JOINTS
(Acrobat 65 K) #3499, 8 pgs.
Wen Rong D.L.Wu--Beijing Institute of Astronautical Systems Engineering
ABSTRACT: Plays of joints strongly influence the dynamics of the large deployable space structures. In this paper, dynamic simulation of space structures with pinned joints is discussed. The study can be simply divided into two parts: the flexible effect of structure is simulated by MSC/NASTRAN, and the global motion of rigid body by DADS. The details of how to select the deformation modes in MSC/NASTRAN and how to deal with the digital problems in DADS will be given.
Keywords: Space Structures Gap Deployable Nonlinear MSC/NASTRAN DADS
IMPROVEMENTS TO THE DOUBLET-LATTICE METHOD IN MSC/NASTRAN(Acrobat 98 K) #3799, 16 pgs.
William P. Rodden--William P. Rodden, Ph.D., Inc.
Paul F. Taylor--Gulfstream Aerospace Corporation
Samuel C. McIntosh, Jr.--McIntosh Structural Dynamics, Inc.
ABSTRACT:The Doublet-Lattice Method (DLM) is in use worldwide for flutter and dynamic response analyses of aircraft at subsonic speeds. The DLM is an aerodynamic finite element method for modeling oscillating lifting surfaces that reduces to the Vortex-Lattice Method at zero reduced frequency. The number of finite elements (boxes) required for accurate results depends on aspect ratio and reduced frequency, among other parameters. At high reduced frequency, the chordwise dimension of the boxes must be small. A new version of the DLM relaxes limitations of the previous version to permit higher box aspect ratios so that the number of spanwise divisions (strips) can be reduced significantly, leading to a reduction in the total number of boxes. The new version also improves the accuracy of predicted aerodynamic damping. The new version has been integrated into MSC/NASTRAN as a no-charge option that is selected using a NASTRAN system cell.

The present paper summarizes the chordwise and spanwise convergence criteria and presents examples illustrating new modeling guidelines, a tip correction to reduce the sensitivity to the number of spanwise strips, and the reduced computing time possible with the new version.

INFLUENCE OF MODELING FOR ORTHOTROPIC MATERIALS PROPERTIES(Acrobat 390K) #3699, 7 pgs.
Ernst Dieter Sach, Georg Fleischmann andWilfried Ulrich--DaimlerChrysler Aerospace AG
ABSTRACT: Shell type structures are usually modeled with plate elements (CQUAD, CTRIA). In case of thermal loads and orthotropic thermal expansion coefficients the analytical results do not represent the real behavior with sufficient accuracy. The reason is that changes in the thickness are not considered in the element stress/strain description which is correct for flat plates only. However, when a curvature is present, this effect leads to additional stresses and displacements.

As example a nozzle made of carbon fiber reinforced ceramics is used. For comparison an equivalent modeling with solid elements where the orthotropic properties can be fully represented, is applied. The differences in the results of the two models are shown.

AN INTEGRATED APPROACH TO RANDOM ANALYSIS USING  MSC/PATRAN WITH MSC/NASTRAN
(Acrobat 520 K) #1099, 23 pgs.
Anthony Devenport--Northrop Grumman Corporation
Jim Leedom and Mohan Barbela--The MacNeal Schwendler Corporation
ABSTRACT:This paper describes an integrated and efficient approach to random analysis using MSC/PATRAN with MSC/NASTRAN. New enhancements available in MSC/PATRAN provide the analyst with an interactive pre- and post-processing environment for random analysis. These new features will be discussed and results presented demonstrating how the new capability was used on two different industry case studies. Performance improvements using the MSC/NASTRAN directaccess results database (xdb) over the standard output2 file will also be presented.
MICRO ELECTRONIC COMPONENTS VIBRATION FATIGUE DAMAGE EVALUATION(Acrobat 98K) #3399, 9 pgs.
T. E. Wong, F. W. Palmieri, B. A. Reed and H. M. Cohen--Raytheon Systems Company
ABSTRACT:In the current analysis tools, the outputs of random vibration analysis are limited to spectral densities and root-mean-square values of the strain components with no phase information, which is required to be able to correlate the strains and thus calculate von Mises strain resultant. In addition, due to the lack of phase information, it is impossible to use a macro-micro modeling technique, which is based on interpolation of the solution from an initial, relatively coarse, global model on the nodes at the appropriate parts of the boundary of the refined-meshed submodel, to determine the strains in the submodel. The objective of the present study is to develop a methodology to determine strains in electronic components (micro level) resulting from exposure of modules (macro level) to random vibration environments. Specifically, it addresses the problem associated with the analysis of almost microscopic elements attached to larger physical structures, e.g., ball grid array (BGA) solder balls attached to printed wiring board (PWB).

The proposed methodology includes two stages. The cross correlation of output displacement responses versus frequency for each of the degree of freedom of the connection points of the micro model to macro structure is first developed using a NASTRAN ™frequency response analysis of the macro model. In the second stage, a static analysis is conducted using NASTRAN ™ to generate the transfer functions of von Mises equivalent strains for each of the input source loading conditions. These transfer functions are then statistically correlated with the degree of correlation determined by the cross-spectral density in the first stage to calculate the auto-spectral density of the von Mises strains. In the methodology development process, several in-house developed Fortran computer programs, in conjunction with the outputs obtained from NASTRANTM static and frequency response analyses, are used to perform the required computations. An example of 600-pin BGA soldered onto the PWB is illustrated in the present study. Developing test modules, on which various sizes of the BGAs will be soldered, is currently under way to validate the proposed methodology.

ON CALCULATING THE RESPONSE OF AEROJET ENGINES WITH ROTOR IMBALANCE AND NON-LINEAR BEARINGS(Acrobat 228K) #2899, 14 pgs.
David Bella and Leo Dunne--CDH GmbH
ABSTRACT: Non-linear bearings are commonly used between the rotors and casing of aerojet engines. For rotor imbalance response calculations, these nonlinear components are often modeled as linear elements to avoid using the time consuming procedures required for nonlinear analysis. The standard procedure to determine the engine response requires several analyses in which the response of the previous run is used to determine the linear bearing properties for the new run. This iterative procedure is time consuming and neglects the engine response due to the nonlinearities of the bearings. The methodology presented allows for efficient  calculation of nonlinear response due to nonlinear bearings. The procedure is more stable and less resource intensive than a direct time-domain calculation and does not require manual iteration of bearing properties.

The analysis method takes advantage of the harmonic nature of rotor imbalance excitation and resulting engine response. The engine and bearing properties are transformed to a harmonic or frequency-domain representation. The system equations are then solved using an iterative procedure to determine the bearing properties and engine response. The iterative procedure calculates the response for one rotor revolution, the delity of the response is controlled by the number of harmonics used in the calculation. After the iterative calculation has converged, the system harmonic response is transformed to the time domain for standard data recovery. Suggestions for further improvements are also made.

OPTIMIZED SPARSE SOLVER IN MSC/NASTRAN FOR COMPAQ ALPHA-BASED ARCHITECTURE
(Acrobat  65K) #1199K, 15 pgs.
Susanne Balle,Chuck Newman, and Pari Rajaram--Compaq Computer Corporation
ABSTRACT: Numerical simulations of stress, vibration, and heat transfer for the analysis and optimization of structures and mechanical components are now mainstream engineering tools in the Aerospace and Automotive industries. As models become larger and more sophisticated, prediction accuracy increases, but computers need to work faster to keep turnaround time and throughput acceptable. In this paper we present substantially enhanced MSC/NASTRAN performance results using new sparse solvers, fully optimized for Compaq's test 64-bit Alpha systems. The combination brings true supercomputer power to the user, and offers the capacity to process a large number of analyses and the capability to solve large simulations fast and affordably, with direct benefit in time-to-market and product quality. The technologies used for CPU, system, and solver performance optimization, and the improvements achieved, are discussed and quantitative comparisons are made.
PARTNERING FOR SUCCESS(Acrobat 33K) #0999, 5 pgs.
John Hobday--British Aerospace Airbus Limited
ABSTRACT: In order for the Airbus Concurrent Engineering (ACE) project, and subsequently the next major Aircraft program to achieve ambitious targets of time and cost reduction, it was recognised that a substantially different and closer relationship with our IT Partners would be necessary. Partnerships were initially discussed with Computervision and Hewlett Packard, the aspiration of win-win scenarios and comfortable relationships proved difficult to achieve. In the early years of the ACE project (95-98) a lot was learnt by all involved about what Partnerships really were and the considerable effort and conciliation required by all involved to make them effective.
The ACE project has recently undergone a major re-organisation (1stQtr99) which has coincided with the widening of the project to include other IT Partners to support our objective of delivering process improvements across the entire A/C Lifecycle from product concept to demise.

This presentation now monopolises upon the learning of the past three years. I shall attempt to communicate our vision of a generic Partnership Operating Framework, which will be contractually binding for both Airbus and our IT Partners and is the process reference standard against which our mutual engagement and respective performance in support of the Partnership modus operandi will be measured.

THE PRIMARY STRUCTURE OF COMMERCIAL TRANSPORT AIRCRAFT WINGS: RAPID GENERATION OF FINITE ELEMENT MODELS USING KNOWLEDGE-BASED METHODS(Acrobat 358K) #2999, 13 pgs.
Dave Rondeau and Kostas Soumilas--British Aerospace Airbus
ABSTRACT: Early decisions in the development of a new aircraft programme depend critically on the availability of high fidelity structural analysis to validate design principles and quantify the effect of design changes on structural performance. This paper details British Aerospace's (BAe) progress in the development of a tool to produce MSC/NASTRAN data decks of commercial transport aircraft wings, in hours, rather than months. The tool is integrated into British Aerospace Airbus Generic Transport Aircraft (GTA) knowledge-based design tool, created using the ICAD Design Language.

The GTA knowledge-based design tool enables a project team to design, analyse and optimise the primary structure of civil aircraft wings before creation and submission of MSC/NASTRAN decks. The tool rapidly produces consistent, high quality designs enabling several concepts to be considered during preliminary design 1 . It integrates surface geometry, structural layouts, 3D solid modelling, structural analysis, optimisation, manufacturability, weight and cost prediction to enable multi-disciplinary optimisation to be exploited. Recent developments have enabled the production of loads loop finite element (FE) models for a number of projects in a fraction of the time previously required.

The use of feature based modelling is also discussed, showing examples of where FE models of irregular assemblies, such as aircraft cockpit structure, can be rapidly generated. An example is shown using feature based methods to model the undercarriage attachment structure of a large civil transport aircraft.

The paper concludes that, using knowledge-based systems, it is now feasible to consider finite element modelling of wing primary structure to a level of detail previously considered impracticable during preliminary design. It also suggests that it is practical to use the same tools to establish mass/stiffness distributions throughout pre-production phases of the aircraft design cycle.

RELIABILITY ANALYSIS OF BGA PACKAGES- A TOOL FOR DESIGN ENGINEERS
(Acrobat 455K) #3599, 6 pgs.
James W. Jones, Jason Li--The MacNeal-Schwendler Corp.
Yuichi Yamazaki, Jidong Yang--The MacNeal-Schwendler Corp., Japan Ltd.
Masaki Shiratori--Yokohama National University
Qiang Yu--Yokohama National University
ABSTRACT: An innovative design and analysis procedure has been developed by The MacNeal-Schwendler Corporation (MSC) that enables the design engineer to perform analysis of Ball Grid Array (BGA) packages in an order of magnitude less time than was previously required by experienced analysts. This procedure captures the analytical expertise of the experienced analyst and makes it available to the design engineer with a minimum of training required.

This is accomplished using MSC's Acumen toolkit concept. MSC/Acumen is a unique programming procedure, which serves as an interface to the MSC/PATRAN pre- and post-processor. MSC/Acumen utilizes HTML programming to create the look and feel of a website devoted to a specific analytical problem. The expertise of the analyst as well as company procedures, processes and other, often proprietary, requirements, are captured by the MSC/Acumen developer.

The design engineer creates the analytical model from icon picks and a selection of pre-defined model components. Material properties are contained in the MSC/Acumen program as well as loading conditions, boundary conditions, and other analytical requirements. The design engineer needs not have an understanding of finite-element analysis to create the models or apply the loading and boundary conditions. The loading sequence is also pre-defined based upon the procedures and practices developed by the analysts or experts responsible for detailed analytical evaluations of such components. Life prediction techniques based upon large strain and creep analysis are used to calculate the location of failure and the number of allowable loading cycles. These techniques are well justified by extensive fatigue data at one of the authors' laboratories at Yokohama National University.

THERMAL ANALYSIS OF A COOLING SYSTEM USING FORCED CONVECTION
(Acrobat 130K) #3099, 14 pgs.
Jan Rune Nilssen -- The Norwegian Defense Research Establishment
ABSTRACT:The objective of this paper is the thermal analysis of a cooling system for a High Power Traveling Wave Tube Amplifier by using forced convection. This cooling system is an integrated part of an Electronic Warfare (EW) suite in The Royal Norwegian Air Force's EW training aircraft.

The analysis uses MSC/PATRAN for modeling and MSC/NASTRAN for the thermal analysis. Later versions of MSC/PATRAN has made it much easier for a design engineer to perform a preliminary thermal design than before. The paper will also show hand calculated values needed to run a thermal analysis with MSC/NASTRAN.

A comparison between analysis results and results from extensive laboratory testing of the actual device are made.

MSC/NASTRAN & MSC/PATRAN

ANALYSIS OF AN AIRCRAFT CARGO NET BARRIER USING MSC/NASTRAN
(Acrobat 228K) #4999, 15 pgs.
Alexander Rutman, Ph.D., Adrian Viisoreanu, Ph.D., Gary Cassatt,  and John Caiazza--Boeing Commercial Airplane Group
ABSTRACT: Aircraft cargo net barriers are designed to arrest the cargo and protect the cabin crew during a survivable crash landing. Compared with metallic or composite aircraft structures, cargo nets are extremely flexible and develop large displacements under loading, making their behavior essentially non-linear and creating convergence problems. This paper presents modeling techniques and cargo net analysis strategy for MSC/NASTRAN solution 106. Parametric studies address the influence of the net initial shape and net - cargo interaction under crash landing conditions.
APPLICATION OF STRUCTURAL OPTIMIZATION ON REDESIGNING THE FRENCH-BRAZILIAN MICRO SATELLITE (Acrobat 163 K) #6399, 14 pgs.
F. M. N. Ravetti, M. Kataoka-Filho and C. A. Vidal--Insituto Nactional de Pesquisas
ABSTRACT:The French-Brazilian Micro Satellite (FBMS) is a scientific satellite, which will be piggyback launched by the rocket Ariane 5. Its most critical design constraints are: the lower bound of 40.0 Hz on the first natural frequency, in order to avoid coupling between the rocket excitation modes and the natural vibration modes of the satellite; and the upper bound of 10.5 kg on the structural mass. The structure of the FBMS is composed of a cylindrical aluminum alloy adapter for connection with the rocket, and eight sandwich panels (each composed of three layers) that define its topology. In this paper, we show the importance of structural optimization and design sensitivity analysis in the redesign cycles of Space Structures, by presenting all the steps taken and the difficulties encountered as we tried to maximize the first natural frequency from the low value of 18.78 Hz obtained with the first trial design, while maintaining the structural mass bellow the predefined upper bound. All the modal and sensitivity analyses as well as the optimization steps were performed using MSC/NASTRAN. The design variable space for the structural optimization steps was composed of the thicknesses of the faces and core of the sandwich panels.
A BREAKTHROUGH IN PARALLEL PERFORMANCE IN MSC/NASTRAN V70.7 (Acrobat 98 K) #5599, 9 pgs.
Louis Komzsik, Stefan Mayer and Petra Poschmann--The MacNeal-Schwendler Corporation
ABSTRACT: More than a decade ago MSC offered the first parallel production system of MSC/NASTRAN. During this decade MSC has intensified its effort on parallel MSC/NASTRAN and is now ready to deliver MSC/NASTRAN V70.7, which contains very important new parallel features. This paper describes these exciting features and provides preliminary performance results for V70.7. We believe that this system marks the best in parallel MSC/NASTRAN performance ever and presents a breakthrough in parallel computing in our market.
CATIA ATTRIBUTE TRANSFER TO MSC/PATRAN FOR AIRCRAFT STRUCTURES (Acrobat 293K) #3899, 7 pgs.
Dave Swabey--GKN Westland Helicopter
ABSTRACT:  GKN Westland Helicopters has adopted Catia as the main depository of geometric data. All future aircraft will be generated with Catia as Exact Solids on a One-Model per Part Basis. This data is then used within Catia to create a FE Degenerate Geometry Assembly of the Parts within an Aircraft Module. The Part Information and attributes, such as plate thickness and beam cross sections, are stored as Attribute Data with Catia. This information is then transferred to Patran via. Bespoke software that extracts the Attribute Data from Catia and writes a data file which is imported into Patran.
Within Patran our PCL code is used to import the Attribute Data and store it as Properties, Arbitrary Beam Sections and Client Data. As the Global Location of the Beam Cross Sections are known then the Beam Orientation and Offsets can be generated automatically and assigned to the properties.

To assist in the checking and use of this data we have generated our own PCL Functions to access and Display this Data, and in particular to display the Beam Cross Sections on the Geometric Curves imported from Catia.

Currently GKN Westland Helicopters is involved in a project, which is using data from Catia for the definition of the Aircraft Structure. As this is an existing aircraft the Catia Definition is a mixture of Exact Solids and Surfaces. This project will give us a good test platform with which to evaluate the process, highlight any problems and determine the best practice methods to be used in future projects.

DETERMINATION OF NONLINEAR STIFFNESS COEFFICIENTS FOR FINITE ELEMENT MODELS WITH APPLICATION TO THE RANDOM VIBRATION PROBLEM(Acrobat 163K) #6199, 14 pgs.
Alexander A. Muravyov--NASA Langley Research Center
ABSTRACT:In this paper, a method for obtaining nonlinear stiffness coefficients in modal coordinates for geometrically nonlinear finite-element models is developed. The method requires application of a finite-element program with a geometrically non-linear static capability. The MSC/NASTRAN code is employed for this purpose.

The equations of motion of a MDOF system are formulated in modal coordinates. A set of linear eigenvectors is used to approximate the solution of the nonlinear problem. The random vibration problem of the MDOF nonlinear system is then considered. The solutions obtained by application of two different versions of a stochastic linearization technique are compared with linear and exact (analytical) solutions in terms of root-mean-square (RMS) displacements and strains for a beam structure.

DEVELOPMENT OF AN AUTOMATED, FREE-BODY FORCES CONSTRUCTOR FOR C-2A(R) AIRFRAME STRUCTURAL ANALYSIS(Acrobat 260K) #4199, 15 pgs.
Kris Wadolkowski--Aerostructures, Inc.
Leigh-Ann Waughtel-- Naval Aviation Depot
ABSTRACT: In carrying out their responsibilities for providing maintenance support for the C-2A(R) Carrier On-Board Delivery (COD) aircraft, the Navy's Research and Engineering Office was faced with the problem of determining proper boundary conditions for their detailed stress models. A commonly used method involves extracting the boundary conditions for a local area from a larger loads-model and it was this approach that was adopted for the development of an automated procedure. In preparation for this effort, an MSC/NASTRAN loads-model of the C-2A(R) airframe was developed from Grumman's ASTRAL model and an interrogable database of internal forces was created. A Windows-based program, with an MSC/NASTRAN for Windows interface feature, was developed to access this database and generate boundary forces for the user-specified region. Output from this program is in MSC/NASTRAN format card images and includes a "starter" file for the detailed stress model.
DIAG-2 GEOMETRIC NON-LINEAR PARAMETERS CALCULATION FOR DIAGONAL TENSION SIMULATION USING
MSC/NASTRAN(Acrobat 163K) #5399, 14 pgs.
Klaus Otto Schwarzmeier--EMBRAER-Empresa Brasileira de Aeronautica S/A
ABSTRACT: The analysis of Diagonal Tension effects on a thin walled reinforced shell structure that buckles under compression/shear loadings is essential. DIAG2 program was written to simulate the non-linear effects due to the skin buckling (under compression/shear) of cylindrical structures with frames (ribs) and stiffeners. The original structure model is therefore changed to simulate the post-buckling behavior of the structure.
INTEGRATING MSC SOFTWARE AND CADSA PROGRAM FOR THE AIRCRAFT DETAIL STRESS ANALYSIS
(Acrobat 98 K) #4499, 12 pgs.
Ming Chiu,Tian-Sheng Wu, Chun-Hui Lee,and Nan-Horng Lee--Aerospace Industrial Development Corporation
ABSTRACT: AIDC has involved several international cooperation projects for commercial airplane for several years. From CAE viewpoint, Structural detail stress analysis and certification analysis reports (such as: FAA/JAA Certification) are two major time and manpower consumer. So, Standardization and automation can further improve analysis processes and shorten working time. Therefore, AIDC has developed a program, Computer Aided Detail Stress Analysis (CADSA), cooperated with MSC/NASTRAN and MSC/PATRAN packages to do the detail stress analysis. This program provided a fast and efficient method to help analyst to do the detail stress analysis and to output formal stress reports. This CADSA program has been applied to some International Cooperation Project, and it has been proven to be very significant benefit on cost reduction and best quality.
INTERFACE ELEMENTS IN GLOBAL/LOCAL ANALYSIS--PART 3: SHELL-TO-SOLID TRANSITION
(Acrobat 520K) #5699, 17 pgs.
John E. Schiermeier and Rajendra K. Kansakar--MSC
Jonathan B. Ransom and W. Jefferson Stroud--NASA Langley Research Center
Mohammad A. Aminpour--Applied Research Associates, Inc.
ABSTRACT: When performing global/local analysis, the issue of connecting dissimilar meshes often arises, especially when refinement is performed. One method of connecting these dissimilar meshes is to use interface elements. In the previous Parts 1 and 2, curve and surface interface elements, implemented for p-element edges and faces in MSC/NASTRAN Version 69 and 70.5, respectively, were presented. In the current Part 3, the shell-to-solid transition, being implemented to connect dissimilar p-element edges with p-element faces, is presented with examples. This transition completes the set of interface tools for global/local analysis.
LOCAL ANALYSIS OF RIVET HOLES USING THE LINEAR GAP TECHNOLOGY OF MSC/NASTRAN
(Acrobat 423K) #5799, 24 pgs.
John McCullough--Bell Helicopter TEXTRON, Inc.
Lance Proctor--The MacNeal-Schwendler Corporation
ABSTRACT:Local analysis of bearing stresses at rivet locations in helicopters provides the information needed to prevent cracks which could lead to catastrophic failures. The analysis has typically been done using nonlinear methods, which can lead to excessive run times. The "linear gap" technology introduced in MSC/NASTRAN V70.5 linear static solution (SOL 101) can be used to assess the bearing stress regions of the skin in an efficient manner. This paper will introduce the methodology and strategies of implementing linear gaps to solve bearing stress problems.
METHODOLOGY FOR CONNECTING STRUT LOADS CALCULATIONS DURING ASSEMBLY AND LAUNCH SEQUENCE OF TWO SPACE STATION MODULES(Acrobat 65K) #5899, 13 pgs.
Sanjay Patel--The MacNeal-Schwendler Corporation
ABSTRACT: This paper outlines the solution method for calculating residual loads in the connecting members (struts) of two space station modules during assembly and launch process using MSC/NASTRAN geometric nonlinear capability. Use of geometric nonlinear capability is essential since, the assembly and launch process the loads and boundary conditions are changing at each step causing the energy redistribution during the process. The process is demonstrated using a small problem and a realistic looking space structure.
MODAL ANALYSIS- AN ELEGANT SOLUTION(Acrobat 260K) #5299, 19 pgs.
Ir. J.J. Wijker, Ir. F.M. Maitimo, and Ing. C.J. de Haan--Fokker Space B.V.
ABSTRACT:In FEM analyses for large and complex structures small structural elements are mostly modelled by scalar elements. These scalar elements represent either stiffness or mass properties. In a linear bifurcation analysis, not only the stiffness matrix but also the geometrical stiffness matrix is needed. However, scalar stiffness elements, as well as GENEL elements and DMIG stiffness input do not possess such geometrical stiffness matrices. Therefore these elements obstruct the buckling analysis. To overcome this problem, a non-linear analysis in conjunction with a classical normal mode analysis is proposed. Zero eigenvalues will define the buckling load and associated buckling mode. The approach will be discussed in this paper and will be illustrated with the buckling analysis of an in-plane loaded simplified deployed solar array.
NEW STANDARDS BASED DATA EXCHANGE "BRIDGE" FOR DESIGN (CAD), ANALYSIS (CAE) AND MANUFACTURING (CAM) OF COMPOSITE STRUCTURES (Acrobat 130K) #4099, 18 pgs.
Keith Hunten--Lockheed Martin Tactical Aircraft Systems (LMTAS)
John Klintworth and Tom Mac-- MacNeal Schwendler Corporation (MSC)
Narendra Pitre--Geometric Software Services Co., Ltd. (GSSL)
Tom Mack-- MacNeal Schwendler Corporation (MSC)
ABSTRACT: ISO/STEP Standards are providing international product data exchange models and versioning procedures for the purpose of capturing and sharing more complete enterprise-wide design, analysis and manufacturing data. In particular, the STEP AP209 Standard (presently at Draft International Standard (DIS) status) is focused on the product design and analysis (simulation) disciplines, and provides for data exchanges that include:
  • design geometry, with its associated configuration management (CM) data
  • idealized geometry, with its associated detailed finite element models and analysis results (FEM/FEA), including associated analysis version control data and critical associations back to the parent design geometry and CM data
  • composite material design and analysis details such as ply and zone shape geometry, ply laminate table stacking sequences, zone laminate percentage ply tables, composite analysis material models, and ply layer analysis results (i.e., "material structure-inside-a-structure" detailed definitions)
    • The benefits of AP209 over current practices are improved quality of the data exchange, automation (speed), and cost sharing via ISO Standard's collaborations between partners and suppliers.

    LMTAS has selected AP209 as a preferred approach for the integration of CAD, CAM and CAE software tools (in particular MSC/PATRAN&NASTRAN, CDT/FiberSIM, and Dassault Systemes CATIA) to meet its composite structural design and analysis process requirements. LMTAS has defined a pilot production implementation scenario, which will be used to demonstrate the robustness and completeness of this multi-discipline dynamic data exchange process, using AP209. This paper documents the role MSC/PATRAN will play in this industrial scenario demonstration, using new product features which have been added to MSC/PATRAN to meet this next generation CAD/CAM/CAE composite structures integrated process.

    THE ON-ORBIT THERMAL-STRUCTURAL ANALYSIS OF THE SPACECRAFT COMPONENT USING MSC/NASTRAN
    (Acrobat 98K) #5999, 8 pgs.
    Lihua Zhang and Yuegen Chen--Beijing Institute of Spacecraft System Engineering

    ABSTRACT:The predicting of thermally induced structural responses of high precision spacecraft components operating in space environment is a complex and interdisciplinary problem. Mainly using the MSC/NASTRAN software, an integrated resolution for the on-orbit thermal-structural response analysis of the spacecraft antenna reflector was presented in this paper. A unified finite element model was used in all associated analyses, including on-orbit heating loads analysis, view factor calculating, thermal analysis to obtain the temperature distributions, structural analysis to obtain thermally induced distortions as well as the best-fit analysis of the distorted reflector.
    OPTIMIZATION OF AERO-STRUCTURES USING MSC/CONSTRUCT(Acrobat 15.6 MB) #5099,  24 pgs.
    Gerald Himmler, Annett Kalmutzke, and Dr. Hans Sippel--MSC Germany
    Walter Huber--MTU Germany
    ABSTRACT:Aircraft and jet engine development requires being economical and reliable. A lot of efforts are taken to reduce the Direct Operating Costs (DOC) and to increase the payload of the aircraft. Therefore it is worth to lower the weight even on small parts. The next step is to reduce the time to market. New procedures like the Simultaneous Engineering come up where the analyst is already integrated into the concept phase of the product development process. Efficient methods of working require powerful optimization algorithms to be provided in addition to the discrete methods (FEM/BEM) proved to support the engineer in the draft and design phase.

    MSC/CONSTRUCT provides an exceptionally fast and easy - to - use conceptional design tool for design engineers and analysts consisting of two options:

      • MSC/CONSTRUCT Topology distributes material within a design space envelope based on the optimum load path.
      • MSC/CONSTRUCT Shape is a non parametric shape optimization, which homogenizes the stress distribution
      Both options are FEM based and use an efficient optimality criteria technique. MSC/NASTRAN is used as the analysis engine (solver) in the optimization cycle. This guarantees reliable results and highest performance.

      MSC/CONSTRUCT is available since late 1997 and is very well accepted within the automotive industry.

      MSC/CONSTRUCT V3.0 will be released in Q2/99. Major highlights are:

      • Eigenvalues as Objective Function
      • Support of Cyclic Symmetry SOL 114
      • Support of single level superelements (SESET)
      • Midside Node Elements in Shape Optimization
      • Update of the Graphical User Interface (GUI) of MSC/PATRAN
      • Mesh Smoother within MSC/PATRAN
    RANDOM RESPONSE ANALYSIS OF PRE-STRESSED STRUCTURES USING MSC/NASTRAN
    (Acrobat 33 K) #5199, 5 pgs.
    Xu Xiaocheng--China Academy of Launch Vehicle Technology
    ABSTRACT:There are the static load, the thermal load and the dynamic load acting on a vehicle structure simultaneously. Hence, the research of design method based on accounting for the coupling effects of the static load, the thermal load and the dynamic load is necessary and important. The random response analysis of pre-stressed structures is one of key problems in this research.The random response analysis of pre-stressed structures using MSC/NASTRAN has been explored, the solution steps and key points are given in this paper. First the modal analysis of pre-stressed structures is done using the nonlinear static solution sequence SOL106,then the random response analysis of pre-stressed structures is completed by the RESTART method and using the frequency response analysis solution sequence SOL111.The verification of this method using some examples is also given in this paper.

    SHAPE OPTIMIZATION IN MSC/NASTRAN AND MSC/PATRAN(Acrobat 358 K) #4899, 15pgs.
    Lance Proctor--The MacNeal-Schwendler Corporation

    ABSTRACT: This paper provides a method for design shape optimization using MSC/PATRAN and MSC/NASTRAN. MSC/PATRAN provides the Graphical User Interface (GUI) to pre-and post-process shape optimization parameters and results. MSC/NASTRAN is used to solve the model and optimize the shape of a structure. This paper is not intended to be a comprehensive review of optimization theory, but rather it is intended to provide a practical process to solving real engineering problems. Two example problems will be used to show the process; one example will use shape optimization only, and one will use both sizing and shape optimization simultaneously.
    STABILITY ANALYSIS OF PLATES AND DOUBLY CURVED SHALLOW SHELLS USING FINITE ELEMENT METHODS AND APPLICATIONS OF MSC/NASTRAN(Acrobat 390K) #5499, 16 pgs.
    Ricardo Nonato Pereira--EMBRAER
    Maher N. Bismarck-Nasr--Instituto Tecnologico de Aeronautica, ITA
    ABSTRACT: A variational formulation of doubly curved shallow shells is presented. The analysis used Reissner's two-field variable variational principle with the transverse displacement w and Airy stress function F as field variable. Euler-Lagrange equations and boundary conditions are obtained. A finite element based on this variational principle preserving C(1) continuity is formulated, and your eigenvalues for free vibrations and buckling analyses are abtained. Applications for free vibrations and buckling analyses in MSC/NASTRAN model are given as well as yours respective geometry shape. Several numerical calculations are presented. The results obtained are discussed and are compared with previous analytical solutions and numerical calculations.
    THERMAL DESIGN ANALYSIS OF A SATELLITE WITH ARTICULATING SOLAR PANELS
    (Acrobat 1.7MB) #3999, 13 pgs.
    Dieter Roos--MAN Technologies
    Alan I. Diner--MacNeal-Schwendler Corporation
    ABSTRACT: Nearly all satellites have articulating components such as solar panels or antennas that cause the geometry of the spacecraft to vary during the orbit. MAN Technologie AG is currently in the preliminary design phase of a constellation of communication satellites. These satellites are earth oriented, except for the solar panels which are gimbaled with two axes of rotations to keep them perpendicular to the solar vector. In the proposed satellite design, the proximity of the solar panels to the radiators makes it necessary to consider the effects of the orbit-varying geometry on the absorbed heat loads and radiation network. This paper describes the orbital thermal analysis of such types of satellites performed using the TRASYS interface in MSC/PATRAN THERMAL. This system proved to be an efficient simulation tool for thermal analysis of a satellite with a complex articulating motion during the various orbits.
    UNCERTAINTY ANALYSIS AND DESIGN WITH MSC/NASTRAN AND PROMENVIR
    (Acrobat 1 MB) #4399, 15 pgs.
    Enrique Marchante --Department of Analysis and Studies. CASA
    ABSTRACT:The intensive use of Finite Element Techniques in structural analysis has been accompanied by the increase in mesh density, sometimes reaching the limits of the current computer resources. The intention is to increase the model accuracy. Nevertheless, to consider data uncertainties in the analysis has been consistently ignored in the past. As a form of compensation, conservative assumptions such as, for example, reduced values for the material strength characteristics, minimum values for dimensional tolerances or factors of safety in the loads, are being considered. This approach covers some sources of uncertainty but others are traditionally ignored, as for example: Youngs modulus. Simulation techniques are the only general method to account for uncertainties, but its application to structural analysis with finite elements has been impossible in the past due to the unavailability of computational resources. Today, the resources are available and the technology exists and is implemented in the PROMENVIR system. It allows to account for uncertainties in the wide range of analysis presently available in MSC/NASTRAN. The general applicability of this methodology and the versatility of the environment is shown via three examples. The first one is oriented to show the possibilities to account for data uncertainty at analysis level. The second one focused on model updating, by definition of uncertain mobile model parameters. The third one deals with the uncertain design, in which the design parameters are treated as uncertain variables.
    USING MSC/NASTRAN AND LMS/PRETEST TO FIND AN OPTIMAL SENSOR PLACEMENT FOR MODAL IDENTIFICATION AND CORRELATION OF AEROSPACE STRUCTURES
    (Acrobat 195K) #6099, 12 pgs.
    Tom Van Langenhove andMarc Brughmans--LMS International
    ABSTRACT:As time-to-market also in aerospace begins to play a crucial role, accurate predictions and simulations of the behavior of new structures based on analytical models become more and more important. A modal identification must be performed to obtain modal parameters which can be compared with the pre-test analytical results using correlation techniques. Based on the outcome of the correlation analysis, the analytical models must be ‘updated' such that they more accurately predict the actual test results. Since often the time is lacking to validate each component separately, it is a great challenge to define an optimal sensor set for the complete assembly, including internal components. Also, new materials, hyper-new design and not to forget the ever growing model sizes do not make the job more easy. This paper approaches the sensor placement problem from the standpoint of the structural dynamicist who must use the modal parameters obtained during a ground vibration, or eventually an on-orbit test, to perform a test-analysis correlation and updating analysis. The paper also explains which tools are available to make his life easier. A good choice is crucial not only for experimental observability of the dynamic behavior of the structure, but also for the accuracy of the reduced matrices (for orthogonality calculations). Eventually it will help also the modal analysist during his tests and it will make the (often-difficult) geometric correlation obsolete.
    Optimization

    NVH OPTIMIZATION ON NEC SUPERCOMPUTERS USING MSC/NASTRAN
    (Acrobat 1.7MB) #0599, 14 pgs.
    Dr. Himanshu Misra--NEC Systems, Inc.
    Dr. Erwin Johnson and Dr. Louis Komzsik--The MacNeal-Schwendler Corporation
    ABSTRACT: NVH (Noise, Vibration and Harshness) Optimization has now gained popularity in driving the automotive design process using frequency response analysis of detailed full vehicle structural-acoustic models. Usual design targets include minimization of vehicle weight, the adjustment of fundamental eigenmodes and the minimization of acoustic pressure at selected vehicle locations. Typical NVH Optimization analyses require considerable computational resources, both in terms of cputime as well as memory. The availability of state-of-the-art high performance hardware coupled with software advances and improved methodology has made it possible to solve complicated NVH dynamic response problems very efficiently.

    With the introduction of Adjoint Sensitivity Method in V70, MSC/NASTRAN has been increasingly used to perform large NVH Optimization analyses that were unimaginable with the Direct Method. The Adjoint Method usually requires a fraction of the computer resources to produce sensitivity coefficients as compared with the Direct Method. However, for extremely large NVH Analyses, the sensitivity calculations are very demanding in terms of cputime, especially in the context of Vector machines. The calculation of sensitivity coefficients is done inside the DSADJ module of MSC/NASTRAN. For V70.5 and V71, NEC initiated a project with MacNeal-Schwendler Corporation to address the performance bottleneck in the DSADJ module of MSC/NASTRAN. The DSADJ Module Performance Enhancement Project was done with the guidance of MSC and these enhancements are available exclusively on NEC platforms.

    The DSADJ module was totally redesigned to improve vectorization and to exploit the vector architecture of NEC SX-4 and SX-5 Series Supercomputers. In this paper, automotive customers' NVH Optimization applications are presented to demonstrate the performance improvements of the DSADJ module. Dramatic improvements in the DSADJ module resulting in approximately 8-9 fold performance improvement as compared with V70 were observed for NVH Optimization. With the tremendous improvements in the performance of the DSADJ module, and the fact that the eigenvalue analysis involved in NVH Optimization is inherently highly vectorized, NEC Supercomputers are well suited for running large NVH Optimization Analyses using MSC/NASTRAN.

    PARAMETRIC DESIGN/ANALYSIS WITH MSC/PATRAN- A NEW CAPABILITY
    (Acrobat 4.7MB) #0899, 17 pgs.
    James G. Crose, Douglas A. Marx, Mark Kranz, Paul Olson and Carl Ball--MacNeal Schwendler Corporation
    ABSTRACT: This paper describes a new capability of PATRAN to provide for automated parametric analysis in support of complex design processes. Computational resources are available today that can efficiently permit at least an order of magnitude more analysis support to the design process than was available only a few years ago. MSC has been participating in DARPA's RaDEO(Rapid Design Exploration and Optimization) project with Ford Motor Company and the Rocketdyne and St.Louis divisions of Boeing Aircraft Company. That project has developed a new computer program to facilitate robust design processes that involve orders of magnitude more analytical simulation than is typically applied in design. The Robust Design Computational System (RDCS) computer program provides for automation of design processes such as parametric design scanning, application of Taguchi concepts, optimization and probabilistic analysis. It (RDCS) depends on the automation of multi-disciplinary parametric math models that simulate the behavior of the object being designed. It is this requirement for automation that is addressed in the paper.

    MSC is supporting RDCS by creating a powerful parameterization capability with the PATRAN pre and post-processor. The present result of this effort is a modification of PATRAN that permits the use of named variables to replace the usual fixed numerical values of the modeling parameters. These variable names are captured in the session file along with a default value. In addition, the values of these parameters different than the prescribed default can be provided in an external file that can be produced by another code such as the RDCS code referred to above. The goal of the PATRAN parameterization project is to make it possible for the user to use names and default values for variables (parameters) in every entry point on every form that can be accessed for modeling purposes. This goal has now been met for a large fraction of all the PATRAN forms. Similarly, we have provided for the definition and output of named response parameters such as maxima and minima of stress, strain, displacements and complex functions of results ( e.g.,Von Mises stresses or other measures of failure). These responses are directed to an output file for use by other codes such as the RDCS code referred to above.

    Since a PATRAN session file can be re-run in a batch mode, including running the analysis preference, the parameterized version of this file can also be executed in batch mode. This makes it possible to simulate the response of an unlimited number of design variations and capture the responses as a function of the parametric variables and do so in batch mode without user intervention.

    This paper will present a description of this new capability that can be added to PATRAN and show numerous examples of its use. Also, the coupling with RDCS will be described

    THREE DIMENSIONAL SHAPE OPTIMIZATION WITH PROBABILISTIC CONSTRAINTS USING PARAMETRIC SESSION FILES(Acrobat 130 K) #0699, 15 pgs.
    Jeffrey M. Brown--Air Force Research Laboratory, Wright Patterson AFB
    ABSTRACT: Probabilistic analysis is rapidly developing into a desirable tool to improve design processes. Incorporating probabilistics with optimization of three dimensional components is a step towards improving many current deterministic design systems. This paper develops a general purpose method using MSC/PATRAN and MSC/NASTRAN for three dimensional shape optimization that incorporates probabilistic calculations. A parametric finite element model calculates design point responses and semi-analytic geometry sensitivities. The Advanced Mean Value First Order Second Moment Method is used for reliability calculations while sensitivities to the probability constraints are calculated analytically. Demonstration problems are conducted on a cantilever beam, turbine engine disk, and turbine engine blade.
    USE OF DSA ANALYSIS RESULTS FOR RITZ FAST ANALYSIS OF PERTURBED MODELS (Acrobat 228K) #0799, 11 pgs.
    Dr. J.N Bricout and J.M. Leduigou--Centre National d'Etudes Spatiales
    ABSTRACT: Finite element analysts often have to perform analysis of perturbed models in order to validate the dimensioning through sensitivity analysis. This is also the case during Finite Element model updating process or for stochastic dynamic analysis where we want to obtain a statistical description of a solution, provided the statistical distributions of some design driving physical parameters. These analyses often lead to a huge amount of calculations if the analysis is performed using a loop inside a Finite Element software. CNES has developed a fast dynamic reanalysis method based on a Ritz formulation using the results of a Design Sensitivity Analysis performed with MSC/NASTRAN in order to introduce the variation of some physical parameters in the analysis. This paper presents the basic developments and implementation of this method.
    Space

    MODAL TEST CORRELATION AND ERROR LOCALIZATION FOR FINITE ELEMENT MODELS OF SPACECRAFT STRUCTURES(Acrobat 390K) #1599, 18 pgs.
    J. Lopez-Diez, V. Marco-Gomez, and C.Cuerno-Rejado--Universidad Politecnica de Madrid, E.T.S.I. Aeronauticos
    Pedro Luengo--Construcciones Aeronáuticas S.A.(CASA), Spain

    ABSTRACT: This paper describes the use of some tools for matching modal test data an finite element model results. Different reduction/expansion techniques have been implemented in order to become analytical and experimental models size compatible. MAC, NCO and SCO coefficients allow quantifying the degree of correlation between analysis and test results. An error localisation technique based on Mass and Stiffness Baruch's method updating has been implemented. The analytical model of the structure is updated on the basis of experimental data using a direct updating method and new stiffness and mass matrices are generated. The error vector technique assigns errors calculated on stiffness and mass matrices to the different elements of the model. Thence, they are plotted on the mesh, and its colour denotes the amount of error. The process of error interpretation is simplified and physical meaning can be deduced. Modes measured in tests are expanded and plotted and visual comparison of mode shapes (analytical determined and experimentally measured) is performed. The influences of the boundary conditions simulation and sensor location are investigated.

    Algorithms to calculate different correlation parameters, reduction/expansion methods and tools for error location have been implemented in DMAP. Therefore, they can be included in most of the finite element models developed in MSC/NASTRAN. The visualisation on the model results useful in order to identify the major modelling error regions. A study on a flat plate is used as benchmark. Finally, results of the application to the Polar Platform Panel model are showed.

    MODEL VALIDATION AND TESTING OF INTERNATIONAL SPACE STATION STRUCTURES USING MSC/NASTRAN
    (Acrobat 358K) #1399, 16 pgs.
    Tarun Ghosh--Boeing North American, Inc.
    ABSTRACT: In order to perform analysis to support the design of the International Space Station, mathematical models of the components were generated in the form of finite element models. Test verification of these models is required before the components can be certified for launch. Modal testing is one of the several tests performed on the components for certification. The purpose of the modal tests is to show that the mathematical models have the same dynamic characteristics as the physical models. Namely, that they have the same frequencies, modeshapes and mass properties. As part of the pre-test analysis, fixtures and flexures simulating the boundary conditions need to be validated. When the test article differs from the flight hardware, the actual flight hardware also has to be qualified. In addition, shaker locations for application of forces and accelerometer locations for the collection of response data need to be identified. It is important to identify the target modes, which must satisfy the comparison criteria for frequencies, modeshapes and mass properties. As part of the post-test analysis, the test modeshapes are used to validate the mathematical models. For better correlation with test data, the mathematical model may need to be updated. The purpose of this paper is to show how efficiently MSC/NASTRAN can be used in modal testing and model validation and updating. Features developed and lessons learnt are described in this paper for their general usefulness.
    SPACECRAFT STRUCTURAL ANALYSIS TODAY AND YESTERDAY(Acrobat 650K) #1299, 15 pgs.
    Charles Gamblin, PE-Teledyne Brown Engineering
    ABSTRACT:This paper presents a present-day MSC NASTRAN/PATRAN * static/dynamic FEM of the first Saturn I First Stage Booster (1962). This historic Saturn I launch vehicle was successfully flown nineteen times with one manned launch mission (Apollo 7) an 163 earth orbit practice run for the more historic Apollo 11 moon landing thirty years ago in July 1969. The Saturn I FEM shown is a gross static force and dynamic displacement model with limited stress accuracy. More detailed substructured models would be required for a complete stress analysis, which is the standard operating procedure by today's structural analysis methods.

    In the yesteryear, the original static analysis approach involved the judicious application of free body cuts through the clustered tank booster assembly to expose the indeterminate internal reaction forces. Each tank was considered as a “finite element” in the stack-up of structural stiffness (matrix) components. Applying the laws of static equilibrium, the formation of the redundant equations resulted in a 12x12 stiffness matrix for solution. This paper shows examples of the original redundant equation formulation and the computer analysis output results in free body format.

    UPDATED DYNAMIC ANALYSIS METHODS FOR THE SPACE SHUTTLE SOLID ROCKET MOTOR
    (Acrobat 260K) #1499, 9 pgs.
    Christopher C. Flanigan--Quartus Engineering Incorporated
    Dale Nielsen--Cordant Technologies,Thiokol Corporation
    ABSTRACT:The RSRM dynamic models and analysis procedures were recently updated to take advantage of improvements in computer hardware and software performance. Many new and enhanced features of MSC/NASTRAN were exercised including sparse matrix routines, Lanczos eigensolver, enhanced superelements, and residual vectors. The models and analysis procedures were migrated to Windows NT workstations to take advantage of the price/performance ratio of these platforms.

    The methods upgrade for the RSRM dynamic models has significantly improved ease of use, dramatically reduced computer run times, and minimized the need for custom codes. Important features of the upgraded methods will be presented in the paper. Computer run times using NT workstations will be compared to original analyses performed on Cray mainframes.

    SuperModel & PATRAN

    ESTABLISHING NEW METHODOLOGIES WITH MSC SOFTWARE PRODUCTS TO DEVELOP A 747SP FINITE ELEMENT MODEL FOR FAA CERTIFICATION OF AIRFRAME DESIGN MODIFICATION
    (Acrobat 1.9 MB) #0499, 14 pgs.
    Michael Farley--Raytheon System Company
    ABSTRACT: Raytheon Systems Company Waco has developed a MSC/NASTRAN finite element model from drawings of the Boeing 747SP in support of the SOFIA program. SOFIA (Stratospheric Observatory For Infrared Astronomy) is an airborne observatory housing a 2.5 meter infrared telescope (the largest ever airborne). The SOFIA airborne observatory will take a team of NASA scientists, engineers, and educators above 41,000 feet placing the aircraft above 99% of the earth's obscuring water vapor and providing a view of the universe superior to any earth bound observatory. The 747SP finite element model is playing a significant role in the structural substantiation of the design modifications to the 747SP. There are three phases of finite element model development: the baseline model representing the baseline configuration of the Boeing 747SP, the section 46 design model characterizing all of the design changes reflected in the SOFIA design modification, and the certification model with the final SOFIA design modification incorporated into the full 747SP finite element model. These models are MSC/PATRAN databases defined within MSC/SuperModel. MSC/SuperModel has been used to maintain configuration control of the MSC/PATRAN databases and to establish the pedigree of the model by maintaining the history of the model assembly. Throughout the certification process CAE tools and methods have significantly enhanced productivity and have been used to provide an integrated method of data management and analysis. This paper illustrates the finite element process from airframe modification design to the design certification process, and how the Methods & Finite Element Group at Raytheon Waco has utilized MSC software products to enhance the certification process.