06 CAE Crash simulation

Question 1

How many elements can we afford?

Answer 1

1987 - General mash 100mm, fine mesh 30mm
1997 - “ 30mm, “ 10mm
2008 - “ 7mm, “ 3mm

-> not all details can be captured, penetration is a problem

Question 2

create a reliable model (5)

Answer 2

• define objective(s) of model
• only as complicated as necessary
• use experience
• use model parts which have been validated on a component level
• model validation is essential part

Question 3

parts of model

Answer 3

material
loads
joints
physical properties (thickness, densities)
geometrical description

Question 4

workflow

Answer 4

1) virtual component design
2) subsystem validating
3) full scale-virtual testing
4) full scale testing

Question 5

verify

Answer 5

verify:
- check that the mathematical equations are correctly implemented
- check that the parameters are correctly inputted
- consistent units

Question 6

validating

Answer 6

validating:
- check that the results are close to experimental observations
- code has no errors
- overlaid scans of test on FEM

Question 7

Three level of complexity

Answer 7

1) mass-spring system
2) crash test dummy
3) human body model

Question 8

verify vs. validating

Answer 8

first verify than validate

Question 9

Validation vs. actual load dummy

Answer 9

not the same loads
< realism of boundary conditions
> control of boundary conditions

Question 10

What makes a model useful?

Answer 10

if the model can guide us to a better design.

Question 11

What kind of model can we use?

Answer 11

depends on question. simple to detailed

Question 12

What is a validated model?

Answer 12

a model that closely matches physical tests. (often just some aspects are validated)

Question 13

How much should I trust a model?

Answer 13

don’t fall for blindspots
more complexity or less experience = less trust