1993-1999 MSC Users' Conference Proceedings

Categories

• Aeroelasticity
• Aero Engines
• Aircraft/Aero/Assemblies
• Aircraft Applications
• Analysis Methods
• Applications
• Automobile Applications
• CAE Processes
• Civil Structures
• Composites

Aeroelasticity

AERODYNAMICS-STRUCTURES INTERACTION IN AIRFRAME DESIGN, (Acrobat 999K) #1097, 11pgs.

V.B. Venkayya and V.A. Tischler--Wright-Patterson AFB, Ohio

ABSTRACT: Aerodynamics and structures interaction play a critical role in airframe design. It becomes even more significant when viewed in the context of emerging Multidisciplinary Design Optimization (MDO), because the fidelity of the aerodynamic and structures models improves the reliability of the optimal solutions. The primary airframe components affected by the aero-structures interaction are lifting surfaces such as: wings, canards, fins, vertical and horizontal tails, etc. The flexibility effects on the aerodynamic load predictions on modern aircraft can be very significant. They effect both the steady and unsteady aerodynamic behavior as well as the stability aspects. There is a growing interest in both the national laboratories and in industry to develop Aero-Structures Interaction (ASI) tools.

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

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.

COMPUTATION OF DYNAMIC LOADS ON AIRCRAFT STRUCTURE DUE TO CONTINUOUS GUST USING MSC/NASTRAN, (Acrobat 819K) #0797, 17 pgs.
Eduardo A. Rodrigues and Mauro T. Kamiyama--EMBRAER S.A., Brazil

ABSTRACT: The computation of gust loads on the structure of an aircraft is part of the engineering work during the development and certification phases of a new project. The present work describes the methodology used at EMBRAER to compute dynamic loads caused by atmospheric continuous gusts. The mathematical formulation assumes that the gust phenomenon is described as a stationary random process and that the aircraft dynamics is linear. MSC/NASTRAN is used for obtaining the dynamic system modal data by means of SOL1O3 (normal modes solution), and the modal amplitudes necessary to generate the dynamic system frequency-response functions by means of S0L146 (aeroelastic response solution). An example is given in which the methodology is applied to a modern jet aircraft.

COUPLED AEROELASTIC ANALYSIS OF A  FREE FLIGHT ROCKET(Acrobat 228K) #2399, 11 pgs.
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

COUPLING FLIGHT CONTROL SYSTEM DYNAMICS WITH AEROELASTIC EQUATIONS OF MSC/NASTRAN, (Acrobat 207K) #997, 11 pgs.

Yan Mursal, Pipit Puspitasari, and Nineu Disyani--Aircraft Design Div.,PT.IPTN

ABSTRACT: This paper presents development of a procedure to include flight control system dynamics with aeroelasticity in MSC/NASTRAN. The specific application is on flutter analysis of a twin engine propeller aircraft with the yaw damper flight control system ON. The flutter analysis is performed using the PK-method.

The yaw damper transfer functions are introduced into the aeroelastic equations of motion through a combination of EPOINT and TF entries. One of the extra-points represents the rudder deflection resulting from the yaw damper system. The additional generalized unsteady-aerodynamic forces due to this extra-point are provided with down-washes supplied on DMI entries in the Bulk Data.

The analysis results are presented on V-G and V-F diagrams for two configurations, nominal and yaw damper ON.

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.

INTERFACING EXTERNAL, HIGH ORDER AERODYNAMICS INTO MSC/NASTRAN FOR AEROELASTIC ANALYSES, (Acrobat 748K) #897, 18 pgs., color

Brent Whiting--Boeing Defense and Space Group

Douglas J. Neill--The MSC.Software Corporation

ABSTRACT: In the design of aircraft, it is important to have an accurate simulation of both the structural characteristics and the aerodynamic characteristics of the vehicle. For static aerodynamic loads, MSC/NASTRAN uses unsteady aerodynamics at zero reduced frequency. To utilize the accurate structural representation of MSC/NASTRAN in the computation of aeroelastic loads, it is desirable to incorporate aerodynamic and aeroelastic data into the MSC/NASTRAN solution sequence that better represents the actual geometry of the vehicle. This entails importing data that replaces or augments the unsteady data. The Boeing Company, in conjunction with MSC personnel, has prototyped an interface procedure that allows the static aeroelastic loads computations in MSC/NASTRAN to use the rigid aerodynamic forces and aeroelastic corrections from the A502 High Order Panel Method.

THE MSC FLIGHT LOADS AND DYNAMICS SYSTEM, (Acrobat 54K) #1197, 8 pgs.
Douglas J. Neill and Greg Sikes--The MSC.Software Corporation

ASTRACT: The MSC.Software Corporation (MSC) developed an aeroelastic analysis and design capability in the late 1970's and 1980's as part of MSC/NASTRAN. This capability includes flutter analysis, gust analysis and flight loads calculations. The latter is more suited to preliminary and conceptual design. As aerospace companies move to simulate the aeroelastic behavior of the vehicle early in the design cycle, however, there is a need to augment these capabilities to better fit within the current design processes. This augmentation includes new system architecture concepts, enhanced data management and model management and integrated visualization tools that understand aeroelastic models. Finally, new engineering tools need to be implemented that can better model aeroelastic phenomena at an appropriate level of fidelity for use in both vehicle design and production analysis.

This paper will present the critical requirements of the system as understood from numerous discussions with aerodynamicists, loads analysts, dynamicists and aeroelasticians in the aerospace community. Results from this work-in-progress will be presented where appropriate to illustrate the basic architecture, data flow and usage paradigms and their interaction with the aircraft design process.

Aircraft/Aero/Assemblies

LOCAL STRESS ANALYSIS OF STIFFENED SHELLS USING MSC/NASTRAN'S SHELL AND BEAM p-ELEMENTS, (Acrobat 68MB) #4797, 10 pgs.
Sanjay Patel, Claus Hoff, and Mark Gwillim--The MSC.Software Corporation

ABSTRACT: In large finite element models of aircraft structures, traditional h-elements give sufficient accuracy for most purposes, for example in vibration analysis. However, for local stress analysis of stiffened shells, h-elements may give inaccurate answers at shell-stiffener connections. The paper shows how to use p-elements at those locations where more accurate stresses are required. P-elements work with the existing h-element mesh. A few modifications of the input are necessary to convert local parts of the model into p-elements. The p-version elements improve local stresses significantly. The increase in accuracy is demonstrated on two examples of stiffened shells.

MSC DEVELOPMENTS IN AEROELASTICITY, (Acrobat 41K) #4497, 9 pgs.
Erwin H. Johnson--The MSC.Software Corporation

ABSTRACT: The MSC.Software Corporation has a long history of involvement with aeroelasticity. This paper briefly reviews past development efforts and the current capabilities in this area. Recent developments that have not been incorporated into standard documentation are given somewhat more emphasis. This paper concludes with a discussion of ongoing development activity.

MSC/SUPERMODEL   A CAE DATA MANAGEMENT AND ADVANCED STRUCTURAL MODELING SYSTEM (Acrobat 1.2MB) #4597, 11 pgs., color
Greg Sikes--The MSC.Software Corporation

ABSTRACT: MSC/SuperModel supports the processes typically used in the design of large structures comprised of multiple components, typical of aircraft, jet engines, satellites, and launch vehicles. The engineering design and analysis of these large assembly structures is often conducted at the component level with multiple project engineers or project teams each responsible for a given component. In addition to modeling and simulating the performance of each individual component, the assembled vehicle performance must be verified as well. MSC/SuperModel provides an integrated engineering environment that greatly facilities the coordination and communication of engineering modeling and analysis results data among the project team(s). MSC/SuperModel is a powerful CAE process and data management system with engineering tools for advanced modeling and simulation.

RANDOM ANALYSIS USING MSC/NASTRAN ISHELL MODULE, (Acrobat 1.5MB) #4897, 13 pgs.
Mohan Barbela--The MSC.Software Corporation

ABSTRACT: MSC/NASTRAN version 70 has a new DMAP module called ISHELL that allows users to execute an external program from within MSC/NASTRAN. This module is very powerful and can be used to perform various tasks; for example, sorting, margin of safety calculation, and any data block manipulation using an external user written program. This paper briefly describes the ISHELL DMAP module and the procedure to perform random analysis using MSC/NASTRAN ISHELL DMAP module and an external program.

Aero Engines

CHARACTERIZATION OF MSC/NASTRAN & MSC/ABAQUS ELEMENTS FOR TURBINE, (Acrobat 379K) #2097, 15 pgs.
Lt. Jeff Brown--Air Force Research Lab

ABSTRACT: An accuracy study of MSC/NASTRAN and MSC/ABAQUS three dimensional element types was conducted for turbine engine blade natural frequency analysis. Linear, quadratic, hexahedral, and tetrahedral elements were used with different mesh densities in the frequency and mode shape predictions. These results were compared to bench test data and laser holographic mode shapes. Recommendations are made on the selection of finite element meshes for future analyses.

DEFLECTION ANALYSIS OF AERO GAS TURBINE STRUCTURE DURING PROTOTYPE DEVELOPMENT, (Acrobat 525K) #2197, 10 pgs.
M.Chandrasekaran and K.Ramachandra--Gas Turbine Research Establishment, Bangalore, India

ABSTRACT: This paper presents a refined finite element procedure to obtain the cold dimensions of aero engine structural assembly from the dimensions of larger hot gas flow path and also establish the operating clearances between rotor blades and casings. The effects of stiffness distribution on the circularity of casings-frames assembly and its weight optimization are also discussed.

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.

FINITE ELEMENT ANALYSES OF A LAMINATED BLADE RETENTION SYSTEM, (Acrobat 456K) #2297, 18 .pgs.
Dennis K. McCarthy and Robert T. Fort--McDonnell Douglas Helicopter Systems

ABSTRACT: Design of a helicopter main rotor blade retention system is a challenging problem. This critical system must reliably carry large blade loads while allowing extreme blade motions. Several different methods for blade retention systems are currently in service including laminated metallic stacks (LMS). Due to the lack of precise analytic methods laminated metallic stack systems have historically been developed through test. A methodology, developed by the authors, is presented herein to accurately predict the behavior of a LMS blade retention system. This method uses nonlinear finite element (FE) analysis to predict LMS motions and stresses. Finite element results are interrogated to obtain damage and fatigue life predictions. The analytical results are compared to test data with excellent agreement thus verifying the methodology.

HYDROELASTIC ANALYSIS OF A RECTANGULAR TANK, (Acrobat 271K) #2397, 26 pgs.
M.C. Kim and S.S. Lee--The Aerospace Corporation

ABSTRACT: A hydroelastic analysis of a rectangular tank is performed using MSC/NASTRAN. Natural frequencies of slosh modes and hydroelastic modes are evaluated, and are compared with results from other approaches as well as analytical values.

SNECMA BLADE AND DISK MESHING METHODOLOGY(Acrobat 325K ) #1699, 10 pgs.
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.

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.

Aircraft Applications

ADVANCED COMPOSITES REPAIR ANALYSIS TOOL (ACRAT) (Acrobat 64K) 1996, 12 pgs.

Thomas E. Mack--The MacNeal-Schwendler Corporation
James Y. Song--USAF Advanced Composites Program

ABSTRACT: The Advanced Composites Repair Analysis Tool (ACRAT) has been under development for the USAF Advanced Composites Program Office under an Ogden ALC Design Engineering Program (DEP) Contractual Engineering Task (CET) Order. ACRAT is an integrated prototype software system consisting of commercial-off-the-shelf (COTS) and public domain CAE simulation codes and customized databases. The objective has been to develop Beta versions of this computer aided composite repair design and assessment engineering tool following the provisions and procedures of the ASTM Standard E 1340-90 (Reference 1). The standard guide produces working models early in the development cycle, which allows users and developers to learn functional requirements and appropriate system design details by actually interacting with a series of prototypes. Two Beta versions, of a planned six Beta cycle development effort (three-year program), have been completed to-date. The proposed ACRAT solution will reduce the Air Force's dependence on airframe manufactures for engineering assistance, reduce component scrap rates, reduce aircraft down-time while repairs are being designed or because spare parts are not available, and reduce the manpower spent removing and reinstalling aircraft parts that could have been repaired on-aircraft.

ACRAT's software system design emphasis has been focused on standardized methods of electronic data modeling and exchange; a UNIX-less process management environment which insures geometric configuration management and material release control; integration of COTS and/or public domain software wherever possible to reduce the cost of development while maximizing system functionality and reducing future costs of ownership (upgrading/porting supportability); and a single user friendly graphical user interface (GUI) capable of supporting a wide range of perspective users (field technician or expert CAE/composites engineer).

Four (4) customized database schemas (M&P, Aircraft Design, Composite Repair, Component Test) were designed and sufficiently populated to evaluate each data model's ability to meet specific ACRAT system requirements. These prototype databases, coupled with the ACRAT Executive Control System (ECS) database, represent the foundation upon which the fully self contained ACRAT software system has been built.

CALCULATION WITHIN MSC/NASTRAN OF THE FORCES TRANSMITTED BY MULTIPOINT CONSTRAINTS (MPC) AND THE FORCES GENERATED IN SUPPORT CONSTRAINTS (Acrobat 128K) 1996, 21 pgs.
E. de la Fuente--Instituto Nacional de Técnica Aeroespacial (INTA)
J. San Millán--Instituto Nacional de Técnica Aeroespacial (INTA)

ABSTRACT: This paper describes a procedure that permits the calculation of the forces generated in MPC and SUPORT constraints, in STATIC and DYNAMIC (Frequency response) load cases. These constraints are extensively used in MSC/NASTRAN. In the paper the theoretical bases of the procedure are given, as well as DMAP sequences that allow to calculate these forces, and demonstration examples.

COMBINING ACCELERATION AND DISPLACEMENT DEPENDENT MODAL FREQUENCY RESPONSES USING AN MSC/NASTRAN DMAP ALTER (Acrobat 96K) 1996, 10 pgs.
Alan R. Barnett--Analex Corporation
Timothy W. Widrick--Analex Corporation
Damian R. Ludwiczak--NASA Lewis Research Center

ABSTRACT: Solving for dynamic responses of free-free launch vehicle/spacecraft systems acted upon by buffeting winds is commonly performed throughout the aerospace industry. Due to the unpredictable nature of this wind loading event, these problems are typically solved using frequency response random analysis techniques. To generate dynamic responses for spacecraft with statically-indeterminate interfaces, spacecraft contractors prefer to develop models which have response transformation matrices developed for mode acceleration data recovery. This method transforms spacecraft boundary accelerations and displacements into internal responses. Unfortunately, standard MSC/NASTRAN modal frequency response solution sequences cannot be used to combine acceleration- and displacement-dependent responses required for spacecraft mode acceleration data recovery. External user-written computer codes can be used with MSC/NASTRAN output to perform such combinations, but these methods can be labor and computer resource intensive. Taking advantage of the analytical and computer resource efficiencies inherent within MSC/NASTRAN, a DMAP Alter has been developed to combine acceleration- and displacement-dependent modal frequency responses for performing spacecraft mode acceleration data recovery. The Alter has been used successfully to efficiently solve a common aerospace buffeting wind analysis.

EMB-145 NOSE LANDING GEAR DOOR STRESS ANALYSIS (Acrobat 1.6MB) 1996,14 pgs.
Francisco K. Arakaki--EMBRAER-Empresa Brasileira de Aeronáutica
Filipe K. Honda--EMBRAER-Empresa Brasileira de Aeronáutica
Maria Luci P. Salomão--EMBRAER-Empresa Brasileira de Aeronáutica

ABSTRACT: In the present report the structural analysis of EMBRAER's EMB-145 Aircraft Nose Landing Gear Door (N.L.G.D.) is shown.

The EMB-145 Nose Landing Gear Door is attached to the aircraft fuselage through three hinges which are driven by a hydraulic actuator attached to the central hinge. The EMB-145 N.L.G.D. structure, is made of two solid prepreg carbon/epoxy laminated skins, cold bonded and fastened. Carbon/epoxy tape is used in order to avoid panel buckling and to increase the required stiffness of the Aerodynamic Smoothness Requirements for EMB-145. The hinges are machined from aluminum alloy, attached to the structure by titanium alloy bolts.

The EMB-145 Nose Landing Gear Door is designed to resist the critical aerodynamical loading in normal condition and in case one of the hinges fails.

The EMB-145 Nose Landing Gear Door structural analysis including finite element data, boundary conditions and acting loading are presented in this report. The present output results in MSC/NASTRAN allow one to obtain the most critical condition among all subcases very quickly, when post-processed.

EVALUATION OF AN ANALYTICAL DESIGN TOOL FOR BALLISTIC DYNAMICS SIMULATION (Acrobat 672K) 1996, 13 pgs.
Ashish K. Sareen--Bell Helicopter Textron, Inc.
Michael R. Smith--Bell Helicopter Textron, Inc.

ABSTRACT: Usefulness of ballistic dynamics simulations as a design tool in assessing ballistic tolerance and as an aid in pretest guidance is studied. Accurate simulations of hydraulic ram, including failure mode prediction, can be useful in enhancing survivability and in guiding pretest specimen setup to ensure projectile strike and exit at critical locations, thereby minimizing the cost of expensive development tests. To understand the potential of ballistic simulation as a design tool, MSC/DYTRAN code has been evaluated at Bell Helicopter Textron, Inc. by conducting simulations using projectiles of different sizes to impact and penetrate a generic fluid-filled tank and a composite wing structure containing fuel cells. Projectile trajectory, fluid pressures in the fuel tank, and wing structural response from the analysis are compared with the measured data. The physics of the phenomenon appears to be accurately simulated, indicating that MSC/DYTRAN could be a useful design tool for enhancing ballistic tolerance.

GETTING FEA INTO THE DESIGN PROCESS: RAPID ANALYSIS OF TUBES (Acrobat 667K) #0495, 15 pgs.
Raymond N. Frick, Ph.D., RE.--Pratt & Whitney

ABSTRACT: This paper shows how Pratt & Whitney increased engineering productivity by incorporating finite element analysis (FEA) with MSC/NASTRAN into the design cycle. In particular, Pratt & Whitney has developed a fast, efficient process to analyze external tubes of jet engines called the Preliminary Tube Analysis (PTA) System. This process was originally intended to be a preliminary analysis prior to a more formal analysis. However, it has been proven to be very accurate and is usually the only analysis. This process uses a commercial CAD program, MSC/NASTRAN, and custom pre and post processors. This process enables all tubes for new designs to be analyzed before manufacture and testing. While relating some of the details of the custom programs, the emphasis of this paper will be on the process development; i.e. how finite element analysis can be put to effective use within the design environment. This required understanding the design process, creating custom programs to interface with commercial codes, and applying engineering judgment.

A MSC/DYTRAN SIMULATION OF THE LYNX HELICOPTER MAIN LIFTFRAME COLLAPSE (Acrobat 480K) 1996, 19 pgs.
Marcio J. Cavalcanti--Brazilian Navy
Rade Vignjevic--Cranfield University

ABSTRACT: MSC/DYTRAN, an explicit nonlinear finite element code, was used to determine the collapse characteristics of the Lynx helicopter main liftframe, for the vertical crash case. The liftframe was modelled by the Belytschko-Tsay four node shell elements. The analysis of the influence of the collapse velocity on the component structural failure modes and a sensitivity analysis of the material failure criteria were performed. The increase in crashing velocity from 4 to 8 m/s changed the mode of structural failure from torsional buckling, to bending/axial failure. The material failure criteria, however, did not significantly affect the structure collapse mechanism nor the force vs. displacement results. The MSC/DYTRAN simulation results showed good agreement with the full scale test data.

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.

MSC/NASTRAN FLUTTER ANALYSES OF T-TAILS INCLUDING HORIZONTAL STABILIZER STATIC LIFT EFFECTS AND T-TAIL TRANSONIC DIP (Acrobat 768K) 1996, 10 pgs.
Emil Suciu--Gulfstream Aerospace Corporation

ABSTRACT: An existing method for calculating the effect of static lift of the horizontal stabilizer in yaw and the effect of static deflection of the horizontal stabilizer on T-tail flutter is appended to the MSC/NASTRAN flutter solution. The application of the method to a T-tail of interest shows the expected trends. A strip theory correction scheme is proposed to permit separation and factoring of C L a and C l b on the horizontal stabilizer by different factors. A refinement of the T-tail transonic dip calculated with classical methods is obtainable this way.

MSC/PATRAN AS A PART OF A TOOL IN THE FIELD OF STATIC AND DYNAMIC AEROELASTICITY (Acrobat 1MB) 1996, 8 pgs.
Jari Hyvärinen--Anker-Zemer Engineering AB
Per Kjellgren--Anker-Zemer Engineering AB

ABSTRACT: This paper uses two measures for stability when studying aeroelastic behaviour in problems which require Non-linear fluid mechanics modelling for the solution. One measure is defined for static stability and the other for dynamic stability. The simulation performed on the fluid-structure interaction of a 2D ellipse in a sub critical Reynolds number flow field is shown in this paper.

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.

PREDICTION OF BREAK-OUT PATTERNS FOR AIRCRAFT CANOPIES FRAGILIZED MECHANICALLY OR WITH DETONATING CORD (Acrobat 160K) 1996, 7 pgs.
Rocky Richard Arnold--Leapfrog Technologies, Incorporated
Patrick S. Collins--Leapfrog Technologies, Incorporated

ABSTRACT: This paper presents a methodology for predicting the fragilization behavior of aircraft canopies subjected to either mechanical loading or explosive pressures, or both. Fragilization refers to the process whereby an intrinsically strong and tough polymer canopy material (such as stretched-acrylic or polycarbonate) is cracked, damaged or otherwise weakened in such a manner as to destroy its resistance to mechanical loading created by an egressing pilot or crewmember. The approach adopted uses MSC/NASTRAN as the foundation of a computational procedure that uses fracture mechanics principles to predict crack generation, growth, and propagation (including branching). The computational procedure, called PACE, for Program for Automatic Crack Extension, automatically reconstructs finite element grids according to the growth of crack(s). MSC/NASTRAN is used to predict the dynamic state of stress at, and around a crack tip(s), and PACE includes fracture mechanics modules which use the existing stress state to predict propensity for further cracking. The entire process is automated allowing users to perform a complete analysis without concern for the need for new finite element meshes. At conclusion, the trace of cracks provides the break-out pattern. Ideally, the break-out pattern generates small pieces of material which are estimated to not be harmful to the pilot and crewmembers. This paper reviews the progress of work accomplished to date.

SIMULATION OF A HELICOPTER COCKPIT AIR BAG SYSTEM WITH MSC/DYTRAN (Acrobat 416K) 1996, 14 pgs.
David Furey--Simula Government Products, Inc
rjaan Buijk--MacNeal-Schwendler Corporation
Lindley W. Bark--Simula Government Products

ABSTRACT: In the development of inflatable restraints for automobiles, engineers have become increasingly reliant on analytical methods to support design efforts. Current efforts to develop inflatable restraints for helicopter cockpits are also relying on analytical methods to gain efficiency in the design process. Applying inflatable restraint technologies to a helicopter cockpit is often a retrofit system integration, since typical airframe service lives are on the order of 30 years and new aircraft models remain rare. Thus, since the placement of air bag components is usually not optimum, the trajectory of the deploying air bag must be precisely controlled. This is accomplished with innovative folding schemes and prescribed bag-structure and bag-occupant contacts that will guide the air bag to its desired position. In the majority of helicopter applications, adequate air bag load-bearing surfaces do not exist. This drives the air bag shapes to be fairly complex, compared to an automotive air bag. To meet the challenges of this modeling effort, the MSC/DYTRAN code was selected and modeling techniques have been developed to realistically simulate single- and multiple-bag helicopter air bag systems.

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 1MB), #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].

TURBINE ROTOR BURST CONTAINMENT ANALYSIS USING MSC/DYTRAN AN ANALYTICAL APPROACH TO PREDICTING PRIMARY CONTAINMENT (Acrobat 768K) 1996, 14 pgs.
Kelvin Y. Ng--Hamilton Standard

ABSTRACT: With the common use of turbo-fluid machinery in the aerospace industry, rotor burst containment is an important design requirement. More demanding weight reduction goals are pushing containment structures to the brink of containment efficiency. Design engineers at Hamilton Standard have been reliant on design similarities and empirical data, to predict containability. However, limitations in the current methodology make detailed predictions difficult, especially if the geometry is not based on a previous design. In some cases, the limitations in the empirical method can lead to many costly tests. With the use of MSC/DYTRAN, and the help of the MacNeal-Schwendler Corp., Hamilton Standard has been developing an analytical method to predict rotor burst containment. Preliminary case studies have shown that MSC/DYTRAN can handle the physics involved with turbine rotor containment. Using the analytical methodology, structural damage and material response are characterized from the physics. Therefore, the prediction is independent of similar designs.

A VULNERABILITY MAP OF A COMMERCIAL AIRCRAFT (Acrobat 1.5MB) 1996, 19 pgs.
Y. I. Moon--Wright Patterson AFB
G. Bharatram--Wright Patterson AFB
Capt. S. A. Schimmels--Wright Patterson AFB
Dr. V. B. Venkayya--Wright Patterson AFB

ABSTRACT: A method of developing a vulnerability map of a commercial aircraft is presented using MSC/DYTRAN and MSC/NASTRAN. The intent of the map is to establish the vulnerability of every point in the cargo hold where a bomb can explode. One might interpret each point in the cargo bay as having four dimensions. Three are spatial coordinates and the fourth is the maximum size of the bomb the structure can withstand without catastrophic failure. The vulnerability of the aircraft is examined from two distinct failure scenarios. The first is the response immediately after the bomb explosion. The second is the subsequent flight to the nearest airport for safe landing.

The immediate response analysis is determined with MSC/DYTRAN and the post explosion analysis is made by MSC/NASTRAN. A complete vulnerability map requires many failure scenarios and a large number of MSC/DYTRAN and MSC/NASTRAN analyses. Six points in the cargo hold were critically examined to demonstrate the concept.

Analysis Methods

COUPLING OF MSC/NASTRAN AND BEM STRUCTURAL MATRICES (Acrobat 702K) #0493, 15 pgs.

M. J. MeNamee -- United Technologies Corporation

K. L. Leung -- United Technologies Corporation

P. B. Zavareh -- United Technologies Corporation

ABSTRACT: Accurate stress analysis using a combination of the Finite Element Method (FEM) and the Boundary Element Method (BEM) is achieved by coupling MSC/NASTRAN with symmetric BEM structural matrices through the use of the external superelement technique. A DMAP procedure is developed to incorporate the symmetric stiffness matrix derived by the BEM into the global stiffness matrix generated by MSC/NASTRAN. This coupled MSC/NASTRAN BEM analysis procedure provides a way to exploit the versatility of MSC/NASTRAN in handling wide classes of engineering problems, including those involving nonlinearity and inhomogeneity, while maintaining the accuracy of the BEM in areas of crack and stress concentration. Several analysis examples are given to illustrate the usefulness of the proposed technique.

EXACT CALCULATION OF MINIMUM MARGIN OF SAFETY FOR FREQUENCY RESPONSE ANALYSIS STRESS RESULTS USING YIELDING OR FAILURE THEORIES (Acrobat 465K) #0593, 10 pgs.

Françis Charron -- Université de Sherbrooke

ABSTRACT: In static analysis, the calculation of minimum margins of safety using yielding (Von Mises,...) or failure theories (instability for honeycomb structure,...) requires all stress components (3D case : sigma xx, sigma yy, sigma zz, tau xy, tau xz, tau yz ; both magnitude and sign) for a specific element. In frequency response analysis, the stress component magnitude and sign are functions of the reference phase angle and the phase angle of each of the various stress components. When the phase angle difference between the various stress components is almost equal to 0 or 180 degrees, the calculation of the minimum margin of safety is simple. However, in the general case, the minimum margin of safety will be dependent upon both the reference phase angle, as well as the phase angle of each of the various stress components. This paper describes a method used for the calculation of the exact minimum margin of safety for the general case. For the 2D and 1D elements, the exact minimum margin of safety is evaluated at the lower and upper fibers of the element where the flexural stress is maximum and the transverse shear stress contribution is equal to zero. The calculation of the exact minimum margin of safety is done by a general stress processor using the MSC/NASTRAN OUTPUT2 file.

MSC/NASTRAN SHELL AND SOLID ELEMENT MESH REQUIREMENTS IN THE VICINITY OF A CIRCULAR HOLE STRESS CONCENTRATION (Acrobat 1.04MB) #0393, 18 pgs.

Robert P. Thacker, Jr. -- Boeing Computer Support Services

ABSTRACT: This paper takes a look at the mesh density requirements when the geometry is a flat plate, has a circular hole, and is subjected to a uniform tension along two opposite edges. The program to be used is MSC/NASTRAN, Version 67, a finite element program from the MacNeal-Schwendler Corporation. The elements used are the 8 node parabolic shell, 8 node linear solid, and the 20 node parabolic solid. The objective is to determine the number of elements, in the radial and angular directions, to achieve an accuracy in deflection and in stress of less than 2% error. The mesh density to achieve the 2% error criteria will be checked on all nodes along 3 straight lines, at angles 0, 45, and 90 degrees, from the hole to the edge of the plate and also all nodes around the circumference of the hole.

PARALLEL PROCESSING IN MSC/NASTRAN (Acrobat 500K) #0293, 11 pgs.

Dr. Louis Komzsik -- The MacNeal-Schwendler Corporation

ABSTRACT: The MacNeal-Schwendler Corporation has been researching parallel computational methods and evaluating their applicability to its products since 1985. Limited parallelism has been offered in various MSC/NASTRAN products, mainly on supercomputers, since 1987. Presently, there are 5 major computer platforms where shared memory parallel execution is supported.

The paper will discuss some of the technical details of the shared memory parallel methodology and explore the limitations of parallel speedup on the current parallel environments using MSC/NASTRAN. Results of the leading parallel applications will be shown on a moderate number of processors. Specifically, a 4 fold parallel speedup on 16 CPUs analyzing a large automobile industry job will be demonstrated.

The results of investigations on using a distributed memory methodology (applied in the massively parallel computers) will also be discussed. The main strategic aspect of Lagrange multiplier-based solution sequences and the topic of supermodules will be briefly addressed.

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.

COMPUTATION OF STRESS INTENSITY FACTORS USING MSC/PROBE VERSION 5 (Acrobat 1.16MB) #7693, 20 pgs.

John E. Schiermeier -- The MacNeal-Schwendler Corporation

ABSTRACT: In fracture mechanics, the stress intensity factor is used to determine whether a crack will run, possibly causing catastrophic failure or arrest. Typically, this value can be computed from the stress or displacement fields around the crack tip, either by hand or by numerical methods, and then compared with empirical data.

MSC/PROBE-PLANAR has long had two methods of computing Mode l and II stress intensity factors which take advantage of the p-version, the contour integral and cutoff function methods, as well as the standard energy release rate. In Version 5, MSC/PROBE-SOLID has incorporated singularity elements to model exactly the displacement field for a closed crack, and the crack-opening displacement (COD) method to automatically compute Mode I, II, and III stress intensity factors. Combined with the automatic p-adaptivity, accurate and reliable factors may be computed for fully three-dimensional problems in an efficient manner.

This paper provides an explanation of the stress intensity factors and the methods used to compute them. Sample problems are run, using MSC/XL V3B as the pre- and postprocessor, and the computed stress intensity factors are compared with theoretical results where available.

DESIGN AND ANALYSIS OF CORIOLIS MASS FLOWMETERS USING MSC/NASTRAN (Acrobat 833K) #5493, 17 pgs.

C. P. Stack -- Micro Motion, Inc.

T. J. Cunningham -- Micro Motion, Inc.

ABSTRACT: A Coriolis mass flowmeter measures mass flow directly by vibrating a fluid-conveying pipe at resonance. Design of these meters was facilitated by solving the equations of motion via the finite element method. A complex eigenvalue analysis (SOL107) was necessary due to the presence of the Coriolis force terms in the damping matrix. Performance parameters of the meter can be predicted from the complex eigenvectors and were found to match experimentally determined values to within five percent.

Since vibration occurs during Coriolis meter operation, low stress designs must be used to preclude fatigue failure. This analysis was also performed using MSC/NASTRAN.

DETERMINING TUBE STRESS FROM CBEND ELEMENT FORCES AND MOMENTS (Acrobat 740K) #6493, 15 pgs.

Raymond N. Frick, Ph.D., P.E. -- Pratt & Whitney

ABSTRACT: MSC/NASTRAN is used extensively in the design of external tubing for turbo-fan aircraft engines at Pratt & Whitney. It accurately calculates the stress of tubes under pressure, thermal, and case displacements and also natural frequencies. Many of the external tubes are small diameter (under 3/4 inch) and are part of a complex tube system. The most effective element type for these tubes is a "beam" element such as the CBEND. A complex small diameter tube system modeled with CBEND elements is very efficient compared with the same system modeled with CQUAD4 plate elements. However, while the MSC/NASTRAN CBEND element uses the ASME Code equations to account for the ovalization of the tube in the bends, the stress output is not complete. The in-plane and out-of-plane bending moments are not combined while the torque stress and the hoop stress are ignored. Therefore, the correct principal stresses are not determined. Pratt & Whitney developed a CBEND post-processor which uses the ASME Code equations to determine the complete stress field from the MSC/NASTRAN calculated forces and moments. This paper presents the ASME Code equations used by the CBEND post-processor and compares the results to equivalent plate models. Based upon these comparisons, the use of the MSC/NASTRAN CBEND element has been implemented in the design of small diameter tubes.

THE DEVELOPMENT AND USE OF A MATERIALS DATABASE FOR PRODUCT DESIGN AND COMPONENT LIFING.(Acrobat 228K) #0199, 13 pgs.
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.

DYNAMIC MODELING AND ANALYSIS OF SPINNING POLYGON ASSEMBLIES USING MSC/NASTRAN (Acrobat 438K) #6693, 7 pgs.

Bill Nowak -- Xerox Corporation

Courtney James -- Xerox Corporation

ABSTRACT: This paper describes the application of MSC/NASTRAN to calculate the dynamic response of a spinning polygon, motor, and motor housing used in xerographic printers. Initially, different levels of model sophistication were evaluated showing convergence to a representative model. Using the converged model, the dynamic response of the polygon mirror was evaluated from the effects of base excitation. Frequency correlation in the 0 to 1000 hertz range was demonstrated to be better than 10% when compared to a dynamic modal test. Mechanical gain correlation at the fundamental rotor resonance was of the same order as the modal test with amplitude variations attributed to the assumed damping of the model and differences between empirical and analytical response locations. Conclusions and recommendations on future work are also cited.

ELECTRO-MECHANICAL RESPONSE SIMULATION OF ELECTROSTATIC VOLTMETERS USING MSC/NASTRAN (Acrobat 469K) #6593, 8 pgs.

Bill Nowak -- Xerox Corporation

ABSTRACT: This paper describes the application of MSC/NASTRAN to simulate the electro-mechanical behavior of in situ electrostatic voltmeters. These "tuning fork" style transducers are used to continuously monitor photoconductor voltage during xerographic copier and printer operation. Voltmeter theory of operation is discussed, and finite element model development is detailed showing a 6% correlation of natural frequency with empirical results. From an existence proof, model boundary conditions were adjusted to show correct voltmeter dynamic response. Based on this empirical behavior, structural design modifications were made to the model until similar dynamic response was analytically achieved. These modifications were then applied to the hardware and correct performance was empirically verified. Conclusions and recommendations on future work are also cited.

EXTENDED DETAILED FINITE ELEMENT ANALYSIS OF A 9.6 METRE AUTOGENOUS SAG MILL (Acrobat 1.52MB) #5393, 25 pgs.

John Hadaway -- ANI PRODUCTS

Eric Hecht -- COMPUMOD Pty. Ltd.

ABSTRACT: Finite element analysis is becoming an integral part of the design and manufacturing process of heavy engineering machinery for the mining industry in Australia. The Grinding Mill division of Australian National Industries (ANI) which is the division of ANI responsible for design, manufacture and supply of ore grinding mills to mines throughout Australia and overseas have been using the MSC/NASTRAN finite element analysis code extensively in all phases in the supply of their mills.

The finite element analyses of a 9600 mm diameter (5640 mm length) Autogenous Grinding Mill is used to describe how today's available technology is being used by one company to design and manufacture machinery for the mining industry.

FINITE ELEMENT ANALYSIS OF THE RISER COLUMN CHAINTABLE AND CHAINHAWSE STRUCTURES FOR A FLOATING PRODUCTION STORAGE AND OFFLOADI NG FACILITY USING MSC/NASTRAN (Acrobat 1.92MB) #4393, 17 pgs.

D. J. Twine -- BHP Engineering Pty. Ltd.
Dr. S. Loganathan -- BHP Engineering Pty Ltd

ABSTRACT: An overview is given of a recently completed finite element stress analysis of the Riser Column Chaintable and Chainhawse Structures for an offshore Floating Production Storage and Offloading (FPSO) oil and gas facility.

The project involved finite element modeling of a symmetric half model of the chaintable and analysis of the model under a series of Unit Load Cases and Load Combinations. The primary objective of the analysis was to quantify stress levels and stress combinations throughout the structure to enable strength and fatigue capacity of the chaintable and chainhawse structures to be confirmed.

The model involved approximately 60,000 DOF and analysis was carried out using a CRAY-YMP Supercomputer.

The paper will present a summary description of the problem and objectives of the analysis, finite element discretisation of the structure, analysis approach, and quality assurance checking procedures applied to verify the results.

FINITE ELEMENT ANALYSIS (FEA) OF THE STATIC AND DYNAMIC RESPONSE OF THE SHEET MOLD COMPOUNDING (SMC) STRUCTURE USING THE ENHANCED MODELING TECHNIQUE OF THE ADHESIVE JOINING REGION (Acrobat 589K) #6393, 20 pgs.

Joon B. Park -- Automated Analysis Corporation

Randal H. Visintainer -- Ford Motor Company

ABSTRACT: An FEA study was conducted to examine the static and dynamic response of an SMC structure fabricated by adhesive joining method using MSC/NASTRAN. The appropriate modeling of the adhesive joining region is essential in precise FEA predictions of static and dynamic response of the SMC structure presented. An enhanced modeling technique for the adhesive joining region is presented in this paper. A composite mechanics approach was used to define the mechanical property of finite elements along adhesive joining region. Static and dynamic predictions of the enhanced modeling technique were compared with predictions of the conventional linkage modeling method in structure analysis.

A FINITE ELEMENT METHODOLOGY FOR PREDICTING RELATIVE MOTION OF AVIONICS MODULE CONNECTOR CONTACTS (Acrobat 99K) #4193, 15 pgs.

Mark H. Morton -- Lockheed Aeronautical Systems Company

David S. Layton -- Lockheed Aeronautical Systems Company

ABSTRACT: This paper presents a methodology for modeling and predicting electronic module connector displacements in an advanced avionics system. The system is modeled using finite element theory and the equations of motion solved using MSC/NASTRAN. Emphasis in this paper is placed on the finite element modeling (FEM) approach and reduction scheme. In order to achieve the desired accuracy in analysis, the initial FEM contained over 20,000 degrees of freedom. A FEM of this size is typically cost prohibitive to use and sensitive to numerical instabilities, particularly when the frequency range of interest may be as low as 10 Hertz and exceed 1000 Hertz. Several model reduction schemes and various superelement approaches are examined in an effort to reduce model size and improve numerical stability. Results include guidelines for model reduction of similar type structures, as well as selection of the appropriate eigenvalue solver and associated parameters when using MSC/NASTRAN. Of particular interest to the authors was the random response of the connector. To this end, modal analysis is employed to identify natural modes of vibration. Forced frequency response analysis using the large mass method provides transfer functions between the source excitation and the response at the connector. The transfer functions, along with a user specified input power spectral density function, are used as input to a random analysis. Results include rms displacements and frequencies of the connectors.

MANEUVERING OF THE SPACE STATION/ORBITER DURING AN ASSEMBLY FLIGHT (Acrobat 1.54MB) #3093, 20 pgs.

Paul A. Cooper -- NASA Langley Research Center

Alan E Stockwell -- Lockheed Engineering & Sciences Company

Shih-Chin Wu -- Lockheed Engineering & Sciences Company

ABSTRACT: A large-angle, multi-body, dynamic modeling capability was developed to help validate numerical simulations of the dynamic motion and control forces which occur while berthing Space Station Freedom to the Shuttle Orbiter during early assembly flights. The paper describes the dynamics and control of the station, the attached Shuttle Remote Manipulator System, and the Orbiter during a maneuver from a gravity-gradient attitude to a torque equilibrium attitude using the station reaction control jets. The influence of the elastic behavior of the station and of the remote manipulator system on the attitude control of the station/Orbiter system during the maneuver is investigated. The flexibility of the station and the arm had only a minor influence on the attitude control of the system during the maneuver.

MODELING AND ANALYSIS OF 4-STEP 3-D CARTESIAN BRAIDED COMPOSITES (Acrobat 1.04MB) #7593, 20 pgs.

Soheil Mohajerjasbi -- Boeing Defense & Space Group

ABSTRACT: The fiber architecture of the preform produced in a 4-Step (l x1) 3-D Cartesian braiding process is investigated based on a study of the movement of the fiber carriers on the machine bed. Distinctly different fiber architectures are identified for the interior, boundary, and corner regions of the preform and the composite. Since different fiber architectures will result in different deformation properties, the effective deformation behavior of the composite is expected to be the result of contributions from these different stiffness properties.

In contrast with these findings, some of the present analytical models consider a "unit cell" as a repeat unit for the braided composite, and attempt to model the mechanical behavior of the composite from the properties of this unit cell. This unit cell is in the form of a parallelpiped with yarns connecting between the opposite corners along the body diagonals.

In this paper, a finite element based method is proposed for modeling the structure of the 3-D braided composite, and determining the elastic constants and coefficients of thermal expansion. MSC/NASTRAN is used in modeling the thermoelastic properties of the composite. Estimates of elastic constants and coefficients of thermal expansion are developed as a function of "interior braiding angle".

Among advantages of this technique are simplicity, and the ability to model and study the response of complex shapes subject to complex loads applied at the boundary.

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.

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.

N-250 WINDSHIELD FINITE ELEMENT MODEL (Acrobat 338K) #7893, 10 pgs.

Masduki Suwandi -- Nusantara Aircraft Industry Ltd.

Kurnia Witono -- Nusantara Aircraft Industry Ltd.

Nurdin -- Nusantara Aircraft Industry Ltd.

ABSTRACT: In analyzing the windshield of N-250, - Indonesian / IPTN's latest aircraft product - one major issue is how to model the windshield glass panel and the distribution of the load to its mounting structure. This paper concentrates on this issue.

NON-LINEAR ANALYSIS OF A PROPELLER BLADE RETENTION SYSTEM (Acrobat 480K) #3293, 6 pgs.

John C. Lambert -- United Technologies Corporation

ABSTRACT: A primary problem in the design of aircraft propeller systems is the prediction of blade natural frequencies. A major problem in predicting these frequencies is determination of the blade retention stiffness. This stiffness is difficult to determine due to the many linear and non-linear variables involved in such systems. This paper discusses the manner in which MSC/NASTRAN V65B was used to advance Hamilton Standard's methodology in evaluating blade retention stiffness.

RADIATION HEAT TRANSFER WITH SPECTRAL SURFACE BEHAVIOR (Acrobat 199K) #5593, 7 pgs.

Mike Chainyk -- The MacNeal-Schwendler Corporation

ABSTRACT: Prior to Version 68, MSC/NASTRAN radiation exchange was restricted to ideal black/grey opaque surfaces exhibiting diffuse emission, absorption, and reflection characteristics. Most real surface behavior is considerably more complicated due to varying degrees of specular, spectral, and temperature dependent properties, as well as radiant transmission. Generalized numerical treatment of all of these phenomena simultaneously is beyond the scope of the current Version 68 effort, however, most materials in a practical engineering sense may be characterized by one or two dominant surface conditions. In particular, most solar collection device materials as well as high temperature metals can be satisfactorily described in terms of their spectral and temperature dependent surface properties. This problem class is addressed with a method known as the radiation energy-band approximation.

A REFINED METHOD FOR LIVE-LOAD DISTRIBUTION PREDICTION OF BRIDGES AND COMPARATIVE STUDY (Acrobat 678K) #5293, 20 pgs.

Yohchia Chen, Ph.D., P.E. -- The Pennsylvania State University

ABSTRACT: A refined analysis method is proposed for predicting the distribution of vehicle live loads on bridge girders. An effective and efficient iteration scheme is used to solve the nonlinear equations. Two representative bridge systems are investigated. The obtained results from the proposed method are compared to experimental data and those obtained from other analysis methods. The prediction method for live-load distribution implemented in the current bridge design code is carefully examined. The paper concludes with a number of actual bridge examples and recommendations.

RESPONSE OF PROTECTIVE STRUCTURES TO INTERNAL EXPLOSIONS WITH BLAST VENTING (Acrobat 1.77MB) #4293, 22 pgs.

Y. Kivity -- The MacNeal-Schwendler Company

C. Florie -- The MacNeal-Schwendler Company

H. Lenselink -- The MacNeal-Schwendler Company

ABSTRACT: This paper presents a computational study of the response of generic protective structures to internal blast waves from high explosive charges. The computations are carried out with the three-dimensional program MSC/DYTRAN, with explicit treatment of the fluid-structure interactions inherent to the problem. The modeled generic structures include frangible panels for blast venting and internal partitions for blast wave deflection. The structural description includes both a thin shell approach for thin walled containers and a solid finite element representation for concrete type structures. The flow of the detonation products and the ambient air is described employing an Arbitrary-Lagrange-Euler (ALE) approach. This approach also allows internal partitions to be attached to the ALE mesh without degrading the computational efficiency.

STRUCTURAL ANALYSIS OF AN 85 FT. FREE STANDING TOWER (Acrobat 946K) #3393, 23 pgs.

Paul F. Martin -- Massachusetts Institute of Technology

ABSTRACT: An 85' high rectangular truss type antenna support tower is currently in use. The tower bracing scheme is typical of and similar to other towers used for this application. Tower members were designed using conventional analytical techniques as presented in design codes such as AISC, ANSI/A58.1 and ANSI/EIA-222. Resulting stress analysis showed factors of safety for all members to be satisfactory and capable of sustaining design loads. Since a conventional tower bracing scheme was used, the overall buckling capacity of this tower was assumed to be adequate. Recently a new antenna configuration proposed for use required additional structural analysis of this tower. The resulting analysis included an overall buckling analysis utilizing the MSC/NASTRAN program with the buckling solution sequence. The buckling analysis revealed that the tower was incapable of withstanding the design loads for either the original or the proposed antenna configurations. In conclusion, it should also be noted that the results of this study suggest that other towers currently in use may also be inadequately designed and subject to potential failures.

THERMOMECHANICAL FINITE ELEMENT ANALYSIS OF STIFFENED, UNSYMMETRIC COMPOSITE PANELS WITH TWO DIMENSIONAL MODELS (Acrobat 1.53MB) #3193, 18 pgs.

Craig S. Collier, P.E. -- Lockheed Engineering and Sciences Co., NASA Langley Research Center

Kevin A. Spoth -- Lockheed Engineering and Sciences Co., NASA Langley Research Center

Glenn C. Grassi -- The MacNeal-Schwendler Corporation

ABSTRACT: A method is presented for formulating stiffness terms and thermal coefficients of stiffened, fiber-reinforced composite stiffened panels for input to finite element analysis (FEA). The method is robust enough to handle panels with general cross sectional shapes, including those hich are unsymmetric or unbalanced. New thermal coefficients are introduced to quantify panel response from through-the-thickness temperature gradients. Equations are defined for stiffness, thermal expansion, and thermal bending that consider the full complement of membrane, bending, and membrane-bending coupling. A technique of implementing this capability with a single plane of shell finite elements using the MSC/NASTRAN2 FEA program is revealed. Thermomechanical analyses of an unsymmetric, hat stiffened, metal matrix composite panel are shown to demonstrate the accuracy possible with planar, 2-D FEM's. 3-D FEA results are presented to verify the solutions. Ultimately, the significance of including this additional accuracy in smeared, equivalent plate 2-D models is proved with FEA of an aerospace plane.

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.

VIRTUAL MASS OF FLUID IN EGG-SHAPED DIGESTERS (Acrobat 316 K) #7793, 9 pgs.
Atis A. Liepins -- Simpson Gumpertz & Heger Inc.
Hamid Nazemi -- Simpson Gumpertz & Heger Inc.

ABSTRACT: The MFLUID capability in MSC/NASTRAN-WS is used to calculate the virtual mass of fluid in an egg-shaped digester tank. In earthquake response calculations of this type of tank a finite element analysis of fluid/structure interaction is needed because simplified methods, such as for cylindrical tanks, are not available. Described are observations about the performance of the QUAD4 element for fluid/structure interaction and a verification of the virtual mass matrix. Useful enhancements are proposed.

Automobile Applications

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.

 

ANALYSIS OF FLEXIBLE ROTATING CRANKSHAFT WITH FLEXIBLE ENGINE BLOCK USING MSC/NASTRAN AND DADS(Acrobat 787K) #3595, 15 pgs.
Lee S. Mayer--Computer Aided Design Incorporated
Hans Zeischka--Computer Aided Design Incorporated NV
Frank Maessen--Computer Aided Design Incorporated NV
Marc Scherens--Computer Aided Design Incorporated NV

ABSTRACT: Mechanical engineers most commonly predict stress and vibration of components within complete mechanical systems by the use of Finite Element Analysis (FEA) techniques. The accuracy of predictions depends mainly on applied boundary and loading conditions as well as meshing techniques. Experience has shown that discrepancies between numerical prediction and test data become great when one is dealing with dynamically loaded structures within mechanical systems that undergo large rigid body motion. Such systems typically exhibit geometric non-linearity and non-linear compliance between the different bodies. This publication presents the basic theory of flexible bodies in DADS and the application in the study of interaction between crankshaft and engine block for 4-cylinder and 4-stroke engines in unfired and fired conditions.

ANALYTICAL PREDICTION OF LEAF SPRING BUSHING LOADS USING MSC/NASTRAN AND MDI/ADAMS (Acrobat 2MB) 1996, 16 pgs.
Shahriar Tavakkoli--Ford Motor Company
Farhang Aslani--Ford Motor Company
David S. Rohweder--Ford Motor Company
Satyendra Savanur--Automated Analysis Corporation

ABSTRACT : Analytical loads in leaf spring bushing can be used to perform finite element analysis on brackets that connect the leaf spring to a truck frame. Two models of leaf springs in MSC/NASTRAN and MDI/ADAMS were created to compare the bushing loads predicted by each model. The geometric nonlinear capability of MSC/NASTRAN (SOL 106) was used to predict the bushing loads in MSC/NASTRAN model. The quasi-static simulation capability of MDI/ADAMS was used to predict the bushing loads in MDI/ADAMS model. The analyses simulated the standard jounce and roll tests at The University of Michigan Transportation Research Institute (UMTRI). An accurate prediction of loads in MSC/NASTRAN model provides the benefit of integration that allows us to include the leaf spring model in a full vehicle model to simulate full vehicle lab tests as well as proving ground durability events. Good correlation was obtained between the two models in jounce condition. More effort is underway to establish satisfactory correlation for roll condition.

THE APPLICATION OF FEM-EMA CORRELATION AND VALIDATION TECHNIQUES ON A BODY-IN-WHITE (Acrobat 1.05MB) #0693, 18 pgs.
Marc Brughmans -- LMS International
Kevin Blauwkamp -- GM - Saturn Corporation
Jan Leuridan -- LMS International

ABSTRACT: The paper reviews the application of FEM - EMA correlation and validation techniques to a body-in-white, namely the 1991 GM Saturn four door Sedan. The FEM model of this car consisted of 46830 dof's (half model). A multi-point experimental modal analysis (EMA) survey was executed for 360 response dof's. Classical techniques for correlation analysis such as MAC are applied. The paper introduces, as well, a variation of the MAC calculation that enables a better identification of regions of difference between FEM and EMA. Error localization methods have been applied to identify the regions of the FEM model causing most of the discrepancies between FEM and EMA. An FEM model updating procedure was executed to reduce the difference between FEM and EMA to acceptable limits.

APPLICATION OF A FRF BASED MODEL UPDATING TECHNIQUE FOR THE VALIDATION OF FINITE ELEMENT MODELS OF COMPONENTS OF THE AUTOMOTIVE INDUSTRY (Acrobat 1.77MB) #0795, 20 pgs.
Stefan Lammens--LMS International
Marc Brughmans--LMS International
Jan Leuridan--LMS International
Paul Sas-- Katholieke Universiteit Leuven

ABSTRACT :This paper presents two applications of the RADSER model updating technique (ref. 1). The RADSER technique updates finite element model parameters by solution of a linearised set of equations that optimise the Reduced Analytical Dynamic Stiffness matrix based on Experimental Receptances.

The first application deals with the identification of the dynamice characteristics of rubber mounts.

The second application validates a coarse finite element model of a subframe of a Volvo 480.

BACK LOAD CALCULATION: A METHOD OF MEASURING COMPONENT LOADS WITHOUT LOAD CELLS (Acrobat 1.6MB) 1996, 21 pgs.
P. R. Perumalswami--Ford Motor Company
A. J. Page--Ford Motor Company

ABSTRACT: In general, FEA is used to find stress/strain in a structure once the loading on the structure is known. In this paper, a method to calculate load from known strain using FEA is presented. Compared to the conventional load measurement method, the proposed method produces more accurate loads with less cost and time. In the conventional method, parts of the component in critical load paths are removed and specially designed load cells are welded in their place. This changes the stiffness and mass of the component, altering the load environment. Resulting load path change in the system could become a major source of discrepancy between the measured load and the load in the actual system. Further, due to space limitation, it may not be possible to instrument for simultaneous measurement of all the loads on the component. These limitations are overcome in the proposed measurement technique by using the whole component, unaltered, as its own load cell. Strains at specific strategic locations on the component are measured and load is back calculated from these strain readings. In this method, except to place strain gages on the component surface, no modification is done to the component. To identify the proper locations for strain gage measurements and to back calculate the load from strain, a software developed in-house, called BLC (Back Load Calculator), is used in conjunction with Finite Element Analysis.

This technique is applied to an automobile suspension component. Results show excellent correlation of back calculated load with the actual load. Also a conventionally instrumented (with designed load cell) component is used for comparison. The proposed method consistently showed considerable improvement over the conventional method.

BUMPER DESIGN USING COMPUTER SIMULATION (Acrobat 387K) #1093, 12 pgs.

Hwa-Won Lee -- SsangYong Motor Company

Sung-Kuk Jang -- SsangYong Motor Company

ABSTRACT: In order to meet the current safety standards, it is necessary that a series of destructive tests for new vehicles including automotive bumpers to be performed. These tests are very expensive and time consuming. Therefore, the necessity of economical design and analysis using finite element method is increasing day by day.

This paper attempts to present such a design and analysis method, using relatively simple beam model and fine meshed shell model. The analysis has been performed for center - center pendulum and barrier hits of a bumper system of XENOY™ 1102 newly developed by GEP (General Electric Plastics US) under the process of injection molding.

Finally, the results predicted from finite element method are compared with those of experimental tests to evaluate the analysis procedure.

THE CONTRIBUTION OF PASSENGER SAFETY MEASURES TO THE STRUCTURAL PERFORMANCE IN SPORTS RACING CARS (Acrobat 1.1MB) 1996, 19 pgs.
Mark Roots--Cranfield University
Jason Brown--Cranfield University
Neil Anderson--Cranfield University
Thomas Wanke--Cranfield University
Marco Gadola--Cranfield University

ABSTRACT: This report deals with the modelling of an Automotive Chassis using MSC/NASTRAN. The torsion stiffeness of the chassis was able to be increased by 500% over the initial configuration by judicious design.

In an effort to allocate more science to the problem of roll cage design it was proposed that nonlinear finite element analysis using MSC/NASTRAN would give a good indication of the true load carrying capacity and deflection under load of the roll cage/frame. The analysis carried out was verified by the test programmme on a full scale chassis. This analysis gave results within an accepatable 10% of the test results despite the simplifying assumptions.

This application of MSC/NASTRAN is new as most small automotive manufacturers rely on past experience for their development. This works well for evolutionary design but not for major structural modifications as were carried out. This report highlights the value of MSC/NASTRAN in this application.

DEVELOPMENT OF A METHODOLOGY TO PREDICT THE ROAD NOISE PERFORMANCE CHARACTERISTICS (Acrobat 329K) #0993, 8 pgs.
Mark P. Voutyras -- Chrysler Corporation
William F. Resh -- Chrysler Corporation
Kevin R. Thomson -- Chrysler Corporation

ABSTRACT: This paper describes the development of a methodology for predicting the road noise performance characteristics of an automotive vehicle system. An MSC/NASTRAN finite element model of a complete suspension system was constructed and analyzed for dynamic response. In addition, a customized system simulation software package, GRADAM, was developed for combining the FEA and experimental results in order to assess vehicle structural sensitivity to noise and also to study the effect of suspension design modifications on the interior noise levels. In the model development stage, the FEM modal and frequency response results for all the relevant suspension components were validated by comparing with the corresponding experimental measurements. The interior noise levels were then obtained through the system simulation software. This customized software combines the MSC/NASTRAN force output at suspension-to-body attachment points with the corresponding pressure/force (P/F) experimental data in order to predict the interior noise levels. The methodology developed herein permits the noise pressure levels to be determined for desired frequency domains. Furthermore, this methodology allows design engineers to answer "what if" questions in order to evaluate the effect of suspension design changes on the interior noise levels. It is anticipated that the methodology presented herein will be instrumental in optimizing the noise and vibration (NVH) characteristics of future car lines.

DEVELOPMENT OF A NONLINEAR FREQUENCY RESPONSE PROGRAM FOR SIMULATING VEHICLE RIDE COMFORT (Acrobat 491K) #3795, 9 pgs.
Keuchiro Tsutsui-- ESTECH Corporation
Ray Nogami--ESTECH Corporation
John L. Breti, Ph.D.-- Structural Dynamics Research Corp.