femprimer-part3.ppt

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Fin ite Element Primer fo r Engineers : Part 3

Mike Barton & S. D. Rajan

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Contents

Introduction to the Finite Element Method (FEM)

Steps in Using the FEM (an Example from Solid

Mechanics)

Examples

Commercial FEM Software

Competing Technologies

Future Trends

Internet Resources

References


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Information Available from Various Types of FEM Analysis

Static analysis

Deflection Stresses

Strains

Forces

Energies

Dynamic analysis

Frequencies

Deflection (modeshape)

Stresses

Strains

Forces

Energies

Heat transfer analysis

Temperature

Heat fluxes

Thermal gradients

Heat flow from

convection faces

Fluid analysis

Pressures

Gas temperatures

Convection coefficients

Velocities


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Example FEM Application Areas

Automotive industry

Static analyses Modal analyses

Transient dynamics

Heat transfer

Mechanisms

Fracture mechanics

Metal forming

Crashworthiness

Aerospace industry

Static analyses Modal analyses

Aerodynamics

Transient dynamics

Heat transfer

Fracture mechanics

Creep and plasticity analyses

Composite materials

Aeroelasticity

Metal forming Crashworthiness

Architectural

Soil mechanics

Rock mechanics

Hydraulics

Fracture mechanics

Hydroelasticity


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Variety of FEM Solutions is Wide and Growing Wider

The FEM has been applied to a richly diverse array of scientific

and technological problems.

The next few slides present some examples of the FEM appliedto a variety of real-world design and analysis problems.


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This example shows an intravenous pump modeled

using hexahedral elements.


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Car tires require sophisticated analysis because of their complex geometry, large

deformations, nonlinear material behavior, and varying contact conditions. Brick

elements are used to represent the tread and steel bead, while shell elements are

used in the wall area. Membrane elements are used to represent the tire cords.


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Dynamic analysis of a tuning fork, to find it's first eight modes of vibration.

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Contents

Introduction to the Finite Element Method (FEM) Steps in Using the FEM (an Example from Solid

Mechanics)

Examples



Future Trends

Internet Resources

References


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Commercially Available FEM Software Suites

Here we present a survey of some of the better-knownintegratedFEM software packages. These integratedsystems allow users to perform all facets of FEM analysis,including modeling, meshing, solution and post-processing.

The Internet provides a vast new resource for individualsinterested in the FEM. See the Reference section of thispaper for interesting FEM links to start your Internetresearch.

In addition to the integrated FEM packages listed below,many vendors offer dedicated software for solid modeling,mesh generation, FE equation generation and solution, and

post-processing.


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Contents


Mechanics)

Examples



Future Trends

Internet Resources

References


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Technologies That Compete With the FEM

Other numerical solution methods:

Finite differences

Approximates the derivatives in the differential equation using

difference equations.

Useful for solving heat transfer and fluid mechanics problems.

Works well for two-dimensional regions with boundaries parallel

to the coordinate axes.

Cumbersome when regions have curved boundaries.

Weighted residual methods (not confined to a small subdomain):

Collocation

Subdomain

Least squares*

Galerkins method*

Variational Methods* (not confined to a small subdomain)

* Denotes a method that has been used to formulate finite element

solutions.


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Technologies that Compete With the FEM (cont.)

Prototype Testing

Reliable. Well-understood.

Trusted by regulatory agencies (FAA, DOT, etc.)

Results are essential for calibration of simulation software.

Results are essential to verify modeled results from simulation.

Non destructive testing (NDT) is lowering costs of testing in

general. Expensive, compared to simulation.

Time consuming.

Development programs that rely too much on testing are

increasingly less competitive in todays market.

Faster product development schedules are pressuring the quality ofdevelopment test efforts.

Data integrity is more difficult to maintain, compared to

simulation.


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Contents


Mechanics)

Examples



Future Trends

Internet Resources

References


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Future Trends in the FEM and Simulation (cont.)

Enhanced multiphysics capabilities are coming:

Coupling between numerous physical phenomena.

Ex: Fluid-structural interaction is the most common example. Ex: Semiconductor circuits, EMI and thermal buildup vary with current

densities.

Improved life predictors, improved service estimations.

Increasing use of non-deterministic analysis and design methods:

Statistical modeling of material properties, tolerances, and anticipated loads.

Sensitivity analyses.

Faster and more powerful computer hardware. Massively parallel processing.

Decreasing reliance on testing.

FEM and simulation software available via Internet subscription.


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Contents


Mechanics)

Examples



Future Trends

Internet Resources

References


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Selected FEM Resources on the Internet

The internet offers virtually unlimited resources to persons

interested in the FEM.

The following links are a small sample of FEM sites on theInternet which the author has found useful. Thousands more(at least!) are readily available.

Most commercial FEM developers have extensive presenceon the Internet, with web pages that include companyhistories, descriptions of software products, and example FEMsolutions.

Other good FEM resources on the web originate withacademia, government, and discussion and user groups.

S l t d FEM R th I t t ( t )


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Selected FEM Resources on the Internet (cont.)

http://www.ansys.nethttp://www.engineeringzones.com- A website created to educate people in the latestengineering technologies, manufacturing techniques and software tools. Exellent FEMlinks, including links to all commercial providers of FEM software.

http://www.comco.com/feaworld/feaworld.html - Extensive FEM links, categorizedby analysis type (mechanical, fluids, electromagnetic, etc.)

http://www.engr.usask.ca/%7Emacphed/finite/fe_resources/fe_resources.html-Lists many public domain and shareware programs.

http://sog1.me.qub.ac.uk/- Home page of the the Finite Element Research Group atThe Queen's University of Belfast. Excellent set of FEM links.

http://www.tenlinks.com/cae/- Hundreds of links to useful and interesting CAE cited,including FEM, CAE, free software, and career information.

http://www.gorni.eng.br/- Extensive FEM links.

http://www.nafems.org/- National Agency for Finite Element Methods and Standards(NAFEMS).http://www.6dof.com/


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Contents


Mechanics)

Examples



Future Trends

Internet Resources

References

References


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References

Cashman, J., 2000. Future of Engineering Simulation,ANSYSSolutions, Vol. 2, No. 1, pp. 3-4.

Chandrupatla, T. R. and Ashok D. Belegundu, 1997. Introduction toFinite Elements in Engineering, Prentice Hall, Upper Saddle River,New Jersey.

Kardestuncer, H., 1987. Finite Element Handbook, McGraw-Hill,New York.

Krouse, J., 2000. Physical Testing Gets a Bum Rap,ANSYSSolutions, Vol. 2, No. 2, p. 2.Lentz, J., 1994. Finite Element Analysis Cross Training, unpublished

lecture notes, Honeywell Engines and Systems, Phoenix, Az.Nikishkov, G.V., 1998. Introduction to the Finite Element Method,

unpublished lecture notes, University of Arizona, Tucson, Az.Rajan, S.D., 1998. Finite Elements for Engineers, unpublished

lecture notes, Arizona State University, Tempe, Az.Segerlind, L. J., 1984.Applied Finite Element Analysis, John Wiley

and Sons, New York.

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