what should cae engineers now

What Should CAE Engineers Know and What TheyDo Not Need to Know?15. Nov. 2007

Automotive and Power Train EngineeringProf. Dr.-Ing. M. Meywerk (Automotive Engineering)

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What Should CAE Engineers Knowand What They Do Not Need to Know

Univ.-Prof. Dr.-Ing. Martin MeywerkDepartment of Automotive and Power Train Engineering

Helmut-Schmidt-UniversityUniversity of the Federal Armed Forces, Hamburg

What Should CAE Engineers Know and What TheyDo Not Need to Know?15. Nov. 2007

Automotive and Power Train EngineeringProf. Dr.-Ing. M. Meywerk (Automotive Engineering)

2/14

Introduction

What is the background?Giving lectures both for engineers in industry and students (topic:

CAE methods in automotive engineering). The experiences are the following:

the „pupils“ learn very quick the functionality of buttons and how to produce coloured pictures

the „pupils“ do not want to analyse or interpret the resultsBut: It is very important to anaylse results from CAE-software from

a physical point of view

What Should CAE Engineers Know and What TheyDo Not Need to Know?15. Nov. 2007

Automotive and Power Train EngineeringProf. Dr.-Ing. M. Meywerk (Automotive Engineering)

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Workflow for CAE engineers

Boss: This is our new part in the suspension; are you ableto calculate the durability?

CAE engineer: Yes, of courseBoss: By tomorrow?CAE engineer: By next week!?Boss: ...

Now the work starts for the CAE engineer.

What Should CAE Engineers Know and What TheyDo Not Need to Know?15. Nov. 2007

Automotive and Power Train EngineeringProf. Dr.-Ing. M. Meywerk (Automotive Engineering)

4/14

Modellingphysical → geometrical → mathematical

Simulating (software)

Analysing the results

What Should CAE Engineers Know and What TheyDo Not Need to Know?15. Nov. 2007

Automotive and Power Train EngineeringProf. Dr.-Ing. M. Meywerk (Automotive Engineering)

5/14

Physical ModellingWhich physical phenomena are involved in the problem?⇒ principal physical equations

Which phenomena could be neglected?⇒ assumptions

Simple estimations or experimentsconcerning the assumption have to be done⇒ Final set of equations

possible

chan

geof

A lot of knowledge of physical phenomena is necessary.

What Should CAE Engineers Know and What TheyDo Not Need to Know?15. Nov. 2007

Automotive and Power Train EngineeringProf. Dr.-Ing. M. Meywerk (Automotive Engineering)

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Geometrical modelling

1. CAD-data Clean upunique (not double defined)

anywhere (no holes)

2. Physically motivated modification (strong link to physical modelling)

What Should CAE Engineers Know and What TheyDo Not Need to Know?15. Nov. 2007

Automotive and Power Train EngineeringProf. Dr.-Ing. M. Meywerk (Automotive Engineering)

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Geometrical modellingKleine Bohrung

Kleine Sicke

little hole

little bead

What Should CAE Engineers Know and What TheyDo Not Need to Know?15. Nov. 2007

Automotive and Power Train EngineeringProf. Dr.-Ing. M. Meywerk (Automotive Engineering)

8/14

Physically motivated modifications / simplifications

- a lot of experience is necessary for simplifacation of geometry- anticipation of the solution- simplification is necessary

statics (stress)--oheat conduction+++Modal analysis (eigenvalues)++o

disciplineradiiholesbeads

small

+ can be simplifiedo with restrictions: can be simplified- should not be simplified

What Should CAE Engineers Know and What TheyDo Not Need to Know?15. Nov. 2007

Automotive and Power Train EngineeringProf. Dr.-Ing. M. Meywerk (Automotive Engineering)

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Physically motivated modifications / simplificationsa)

a

b

b/20

a/4

2b/3

c)

b/109x....

4b/5

b)b/20

4b/5b/5

x

b/10

b/5

b/10

b/5

b/10

b/5

d) e)

f)

9x....

modifications dependadditionally to discipline on: Number, shape and location

What Should CAE Engineers Know and What TheyDo Not Need to Know?15. Nov. 2007

Automotive and Power Train EngineeringProf. Dr.-Ing. M. Meywerk (Automotive Engineering)

10/14

Mathematical Modelling

Correct choice of: • solver for ODE • discretization method for PDE• parameter of the solving algorithm

- knowledge of the algorithms is necessary

What Should CAE Engineers Know and What TheyDo Not Need to Know?15. Nov. 2007

Automotive and Power Train EngineeringProf. Dr.-Ing. M. Meywerk (Automotive Engineering)

11/14

Simulating (software)

– knowledge of the most capabilities of the software– knowledge of all relevant input parameters

What Should CAE Engineers Know and What TheyDo Not Need to Know?15. Nov. 2007

Automotive and Power Train EngineeringProf. Dr.-Ing. M. Meywerk (Automotive Engineering)

12/14

Analysing the results

- plausibility of the results- simple estimations- comparison with known facts- conservation of mass, momentum, energyIt is the responsibility of the CAE engineer to check the results!

- basic principles has to be known- simple estimation formulas have to be applied

(known by heart or by book)- basic physical parameters has to be known by heart

What Should CAE Engineers Know and What TheyDo Not Need to Know?15. Nov. 2007

Automotive and Power Train EngineeringProf. Dr.-Ing. M. Meywerk (Automotive Engineering)

13/14

Lack of knowledge

- properties of tensors (of second order)- how to apply simple estimation formulas- broad knowledge of physics- plausibility checks

What Should CAE Engineers Know and What TheyDo Not Need to Know?15. Nov. 2007

Automotive and Power Train EngineeringProf. Dr.-Ing. M. Meywerk (Automotive Engineering)

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Summary

What should CAE Engineers know

• a lot of physics, some numerical mathematics, little CAD facts,how to estimate, how to anticipate, and how to interprete results

and what they do not need to know?

• script languages for pre- or post processing or workflow definition,programming languages e.g. C#, customizing of software

What Should CAE Engineers Know and What TheyDo Not Need to Know?15. Nov. 2007

Automotive and Power Train EngineeringProf. Dr.-Ing. M. Meywerk (Automotive Engineering)

15/14

Demands on knowledge:

basic: bstandard: shigh: h

Classification of CAE engineerCAD engineer : CADCAE standard user : CAECAE specialist (developer) : Spec.

Demands

What Should CAE Engineers Know and What TheyDo Not Need to Know?15. Nov. 2007

Automotive and Power Train EngineeringProf. Dr.-Ing. M. Meywerk (Automotive Engineering)

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Matrix: Demands vs. Classification

Should not be done

b

Crash

s

Spec.

CAE

CAD

hshs hbb

MBSStatic/FEM

What Should CAE Engineers Know and What TheyDo Not Need to Know?15. Nov. 2007

Automotive and Power Train EngineeringProf. Dr.-Ing. M. Meywerk (Automotive Engineering)

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Example: MBS (some keywords)basic: kinematics and kinetics of rigid bodies in three dimensions,

solver for ODE, angles for orientation of rigid bodies(e.g. Euler), simple 1D-force-deflection-laws, …

standard: broad survey of solvers for ODE (incl. one-step, multi-step,implicit, explicit), stiff ODE, survey of orientation descriptionsfor rigid bodies, simple tensor calculus, general3D force / momentum-deflection/rotation law, flexible bodies (Craig Bampton), …

spec.: DAE solver, index 3 systems, floating frame of referenceformulation for flexible bodies in MBS, …

Examples, no complete list!

What Should CAE Engineers Know and What TheyDo Not Need to Know?15. Nov. 2007

Automotive and Power Train EngineeringProf. Dr.-Ing. M. Meywerk (Automotive Engineering)

18/14

Example: Continuum Mechanicsbasic: linear material laws, lin. FEA, tensors; limits of the

simplified, linear modelling, …

standard: nonlinear material laws, elasto-plastic, composites,phaenomenological laws, higher order FE, locking effects, …

spec.: alternative discretization method (MLS, Trefftz), adaptivemeshing, compatibility, …

Examples, no complete list!

What Should CAE Engineers Know and What TheyDo Not Need to Know?15. Nov. 2007

Automotive and Power Train EngineeringProf. Dr.-Ing. M. Meywerk (Automotive Engineering)

19/14

Example: Crashbasic: Crash on a low level should not be applied!

standard: nonlinear material laws, elasto-plastic, composites,phaenomenological material laws, foams, reduced/full/selectiveintegration, hourglass modes/control, mass scaling, contactalgorithm, parts of standard MBS, tensors, invariants, time stepcontrol, mass scaling, penetration removal, airbag andrestraint modelling, dummy models, basics of nonlineardynamics, ….

spec.: alternative discretization method (MLS, Trefftz, …), adaptivemeshing, ….

Examples, no complete list!