7.4 Commercial Software Packages

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There are many commercial finite element analysis (FEA) software packages available for vibration

analysis, and they have been so well developed that they have an extensive range of vibration analysis

capabilities. Some software packages are intended for generic engineering structures, for example,

ABAQUS, ADINA, ALGOR, ANSYS, COSMOSWorks, MSC/NASTRAN, DYNA3D, and LS-DYNA. The

others are designed for the vibration analysis of specific vibration problems. For example, the software

package Bridge and the software package LUSAS Bridge are for the vibration analysis of bridges.

Normally, FEA modeling software has the following three major components: a preprocessor, a solver,

and a postprocessor. The preprocessor is responsible for building up geometries, meshing, specification

of element types, material properties, and boundary conditions; the solver solves the matrix equations;

the postprocessor provides visualization of results and outputs the results in different formats. Because of

the fact that those CAD/CAE systems such as CATIA, Unigraphics, Pro/E, and Solidworks have powerful

capabilities for building up geometries, vibration modelers often import geometries from such systems

rather than building them up using the FEA modeling software packages themselves.

In this section, we will select the software packages ABAQUS, ADINA, ALGOR, ANSYS,

COSMOSWorks, MSC/NASTRAN, ABAQUS/Explicit, DYNA3D, and LS-DYNA, and will briefly

introduce their major capabilities for vibration analysis. In fact, the vibration analysis capability is only a

small portion of their total capabilities. All of these packages can perform basic vibration analysis

Natural vibration analysis (generalized eigenvalue problem)

v2Mv ¼ Kv

Rayleigh’s quotient

RðxÞ ¼

xTKx

xTMx

Harmonic response

ð2v2M þ KÞU ¼ F0

uðtÞ ¼

Xj

i¼1

viu_

iðtÞ ¼ Fu_ðtÞ

_u€ ðtÞ þ Lu_ ðtÞ ¼ FT eivt F0

Transient response

Mu€ ðtÞ þ KuðtÞ ¼ FðtÞ

uð0Þ ¼ u0; u_ ð0Þ ¼ u_ 0

(

_u€ ðtÞ þ Lu_ðtÞ ¼ FTFðtÞ

u_ð0Þ ¼ FTMu0; u__ ð0Þ ¼ FTMu_ 0

(

Response spectrum analysis

SuðvÞ ¼ HðvÞSf ðvÞHTðvÞ

HðvÞ ¼ ð2Mv2 þ KÞ21

Vibration Modeling and Software Tools 7-13

© 2005 by Taylor & Francis Group, LLC

including: (1) determination of natural mode shapes and frequencies, (2) transient response, (3) steadystate

response resulting from harmonic loading, and (4) response spectrum analysis. In addition, each of

them has its own strengths in some specific areas. These special capabilities are listed below.

7.4.1 ABAQUS

The ABAQUS software is for linear and nonlinear engineering analyses. Due to its wide range of

functionality, ABAQUS usage spans many industries, including automotive, aerospace and defense,

consumer electronics, manufacturing, medical, and rubber sealing.

Some special capabilities include

* Analysis of the coupled phenomena: thermo-mechanical, thermo-electrical, piezoelectric, pore

fluid flow-mechanical, stress – mass diffusion, and shock and acoustic-structural

* Substructures and submodeling

* Material removal and addition

* Fracture mechanics design evaluation

* Parameterization and parametric studies

* User subroutines

7.4.2 ADINA

The ADINA system offers comprehensive finite element analyses of structures, fluids, and fluid flows with

structural interactions. It is widely used in many fields, including the automotive, aerospace,

manufacturing, nuclear, and biomedical industries, and in civil engineering and research.

Some special dynamic capabilities include

* Contact problems in statics and dynamics

* Substructuring in statics and dynamics

* Wave propagation and shock wave analysis

7.4.3 ALGOR

ALGOR’s Professional Multiphysics includes capabilities for static structural analysis and Mechanical

Event Simulation with linear and nonlinear material models, steady state and transient thermal analysis,

electrostatic analysis, linear dynamics, and steady and unsteady fluid flow analysis. It is used in aerospace

and space exploration; the automotive, transportation, consumer products, electronics, entertainment,

manufacturing, chemical processing and medical industries; in the defense, power, and utility sectors; in

civil engineering and scientific research; and in recreation and sports.

Some special features include

* Rigid-body motion

* Hertzian contact

* Submodeling

* Earthquake simulation

* Fluid – solid interaction

* The EAGLE programming language

7.4.4 ANSYS

ANSYS Software Suite offers capabilities for determining the structural, thermal, acoustic, electrostatic,

magnetostatic, electromagnetic, and fluid-flow behavior of three-dimensional product designs, including

7-14 Vibration and Shock Handbook

© 2005 by Taylor & Francis Group, LLC

the effects of multiphysics. The software simulates complex thermal/mechanical, fluid/structural and

electrostatic/structural interactions. It is widely used in the aerospace, automotive, biomedical

engineering, chemical engineering, civil engineering, communications, consumer products, defense,

electronic packaging, industrial and scientific equipment production, and micro-electromechanical

systems (MEMS) industries.

Some special dynamic capabilities include

* Modal analysis of prestressed structures

* Dynamic Topological design optimization

* Substructuring and submodeling

* Coupled field analysis of thermal-structural, fluid-structural, electrostatic-structural, magnetostructural,

acoustic-structural, thermal-electric, thermal-electromagnetic, fluid-thermal, piezoelectric

fields, and an electromechanical circuit simulator

* A parametric design language

7.4.5 COSMOSWorks

COSMOSWorks offers a wide spectrum of specialized analysis tools to virtually test and analyze

complicated parts and assemblies, and is seamlessly integrated with Solidworks. COSMOSWorks is used

for linear stress, strain, displacement, thermal analysis, design, optimization, and nonlinear analysis.

Combined with ASTAR (Post Dynamics), COSMOSWorks is capable of more advanced dynamic

analysis. It is used in a wide range of industries, including aerospace and defense, automotive and

transportation, civil engineering, consumer products, electrical and electronics, heavy equipment,

marine, medical and power.

The special dynamic features of the ASTAR module are

* Support of uniform and multi-base motion systems; the multi-base motion capability allows

engineers to model structures with nonuniform support excitations.

* Support of the gap-friction element, which lets engineers model drop-test and other dynamic

contact problems.

* The provision for several damper options such as Rayleigh damping, modal damping,

concentrated damping, and composite modal damping.

7.4.6 MSC.Nastran

In 1965, MSC participated in a NASA-sponsored project to develop a unified approach to computerized

structural analysis. The program became known as NASTRAN (NASA Structural Analysis Program); one

of the first efforts to consolidate structural mechanics into a single computer program. The suite of

MSC.Software is used in the space, aircraft, and automotive industries; in rail vehicle development; in

general machinery; and in medical and electromechanical devices. Its capabilities include stress,

vibration, heat transfer, acoustics, aeroelasticity, and coupled system analysis.

MSC.NASTRAN’s special dynamic capabilities include

* Damping

* Direct matrix input

* Dynamic equations of motion

* Residual vector methods

* Enforced motion

* Complex eigenvalue analysis

* Normal mode of preloaded structures

* Dynamic design optimization

* Test-analysis correlation

Vibration Modeling and Software Tools 7-15

© 2005 by Taylor & Francis Group, LLC

7.4.7 ABAQUS/Explicit

ABAQUS/Explicit uses explicit time integration for time stepping and addresses the following special

types of analysis:

* Explicit dynamic response with or without adiabatic heating effects

* Fully coupled transient dynamic temperature – displacement procedure; explicit algorithms are

used for both the mechanical and thermal response

* Annealing for multistep forming simulations

* Acoustic and coupled acoustic-structural analysis

* Automatic adaptive meshing, which allows robust solutions of highly nonlinear problems

7.4.8 DYNA3D

DYNA3D is an explicit finite element program for structural and continuum mechanics problems. Due

to its explicit nature, DYNA3D uses small time steps to integrate the equations of motion and is especially

efficient at solving transient dynamic problems.

The specific analysis capabilities of DYNA3D include

* Static analysis using dynamic relaxation

* Dynamic analysis with static initialization from a NIKE3D implicit analysis

* Various contact slideline options for different contact situations between two bodies

7.4.9 LS-DYNA

LS-DYNA is a general-purpose transient dynamic finite element program, and is suited for complex

dynamics, vibration, and wave propagation problems. Its explicit algorithm can be used for high-speed

impact, shock, and vibration problems. Falling impact, rubber elasticity, and impact on sports goods

(rackets, bats, and helmets) are typical examples of problems that can be handled by LS-DYNA. It is

widely used in earthquake engineering; crashworthiness and occupant safety analysis; metal forming;

biomedical engineering; train crashworthiness testing; sports, airbag, and seat-belt deployment; and in

military, manufacturing, metal cutting, and bird strike applications.

The special capabilities of LS-DYNA include

* FEM-rigid multi-body dynamics coupling

* Underwater shock analysis

* Failure analysis

* Crack propagation analysis

* Real-time acoustics

* Design optimization

* Implicit springback analysis

* Multi-physics coupling

* Adaptive re-meshing

* Smooth particle hydrodynamics

* The element-free meshless method

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