Contact Information
Introduction to Vehicle Crashworthiness Lecture -1 1
Office Phone: Office: Email: Office Hours:
CE 264 Non-linear Finite Element Modeling and Simulation
Web:
Pradeep Mohan (703)726-8538 Research 2, 302 E
[email protected] 2:00 to 4:00 PM on Tuesdays and by appointment http://crash.ncac.gwu.edu/pradeep/
CE 264, Lecture 1
Slide #2
Objective
What is Non-Linear FEM and why study it?
FEM is a numerical analysis technique for obtaining approximate solutions to a wide variety of engineering problems for which an analytical solution does not exist
Non-linearities
Safety Standards
CE 264 Non-linear Finite Element Modeling and Simulation
Material • Stress-strain behavior
Geometry • Change in geometry have a significant effect on the load deformation behavior
CE 264, Lecture 1
Slide #3
1
Federal Motor Vehicle Safety Standards (Part 571)
“Active Safety / Crash Avoidance” - 100 Series
Braking (ABS), electronic stability control (ESC), lighting and signalling
Crash Phase • Minimize risk of injury to occupants, combines the reciprocal aims of absorbing impact and ensuring a survival space
Post-Crash Phase • Interior Trim Flammability and fuel system integrity
301 – Fuel System Integrity
CE 264, Lecture 1
Slide #5
FMVSS 208 – New Regulation
208 – Occupant Crash Protection 214 – Side Impact Protection 216 – Roof Crush Resistance
“Fire-related” - 300 Series
30 mph ( 48 kph) into a fixed barrier 50th percentile Hybrid III dummy in front driver and passenger seats Uses dummy injury measures for regulation • Chest G’s 1M
CE 264, Lecture 1
Slide #46
Prototypes reqd. for crash testing
10000
80000
Difficult to conceive a vehicle design with today’s constraints of regulations and safety without any simulation at all Accurate and robust analytical tools using state state-ofof the-art in computational mechanics and computer hardware are indispensable for crash simulations The contribution of simulation lies in that it complements a testing facility by preventing unnecessary y work from being g done The ideal picture is indeed one of a design, heavily supported by analysis, resulting in building of only those prototypes that are almost certain to pass all final verification testing
Engineering Analysis Methods
100
50
Engineering Analysis
Classical methods
Signiificant cost savings
1985
FE Model Size (elem)
M Made possible by suupercomputers
Regulatory Requirements
Reduce Injuries & Fatalities
Year
Exact
Approximate
Numerical methods
Energy
Boundary Finite Finite Element Difference Elements
CAE: Uses Engineering analysis tools primarily FE, BE and FD methods Linear / Non-Linear: based on material, loading Static / Dynamic: Temporal variation in loading, boundary conditions Quasi Static /Transient are sub-cases of above
