Crashworthiness

Question 1

Explain procedure of accident reconstruction.

Answer 1

Accident Reconstruction
• Data Collection / Accident Investigation
–Accident type, vehicles, injuries
–Gross motions of vehicles and occupants
• Reconstruction
–Calculate severity
–Detailed simulation of system dynamics

Question 2

Name a crash parameter related to velocity.

Answer 2

Crash Parameters
• Delta V:
–is NOT the speed of impact
–described the speed change during a
crash phase
–has been a historical measure of accident
severity

Question 3

Explain Delta-v.

Answer 3

Question 4

Explain relation Delta-V and accelerations.

Answer 4

Question 5

How is Delta-V selected in oblique crashes?

Answer 5

Question 6

Explain Energy in relation to crashes.

Answer 6

Energy
• EBS / BEV / EES / ETS
– equivalent impact speed for a rigid barrier test
– Energy Absorbed in vehicle damage is expressed as an
equivalent speed
E= 1/2 MV2
V=EBS/BEV/EES/ETS

Question 7

Which are the two approaches to estimate crash severity?

Answer 7

Crash Dynamics
• Two Approaches to estimate the crash severity
– Momentum
– Energy

Question 8

What does succesful momentum analysis needs?

Answer 8

Successful Momentum analysis needs:
– Accurate scene evidence
– Vehicle Masses
– Pre-impact speed

Question 9

What does succesful Energy analysis needs?

Answer 9

Successful Energy analysis needs:
– Vehicle Stiffness data
– limited crash speed range (20-70 km/h)

Question 10

How is momentum reconstructions performed?

Answer 10

Momentum Reconstructions
• Scene information:
– Road conditions, weather, location, road geometry
– vehicle orientation at impact
• Vehicle position at rest and/or some pre-impact information

Question 11

Which are the equations for impact?

Answer 11

Question 12

How to solve for unknown v in momentum reconstructions?

Answer 12

Question 13

The relationship between restitution and velocity?

Answer 13

Question 14

What are the limitations with momentum reconstruction?

Answer 14

Question 15

Explain background for the crash model.

Answer 15

Question 16

Explain the energy approach.

Answer 16

Question 17

Explain the Energy calculation.

Answer 17

Question 18

Explain differences between direct and induced damage?

Answer 18

Question 19

Explain the crushable zone.

Answer 19

Question 20

Equations acceleration and velocity in crash tests?

Answer 20

Question 21

Equations velocity and displacement vehicle crash tests.

Answer 21

Question 22

Differences between restrained and unrestrained occupant on velocity/time charts?

Answer 22

Question 23

Explain Force Deformation Characteristics.

Answer 23

Question 24

Curve vehicle deceleration.

Answer 24

Question 25

General structure of car?

Answer 25

Question 26

Which are the load paths?

Answer 26

Question 27

Explain phases of vehicle deceleration.

Answer 27

Question 28

Vehicle deceleration force curves.

Answer 28

Question 29

Detailed load paths?

Answer 29

Question 30

Explain Estimation of structure force.

Answer 30

Question 31

Explain the compromise of compatibility/aggressivity.

Answer 31

Compatibility/Aggressivity • Vehicle structural response can be considered to consist of a “compromise” – Self Protection: Can the vehicle protect its own occupants? – Aggressivity: Does the vehicle protect itself at the expense of its collision partner?

Question 32

Which are the Compatibility Categories?

Answer 32

Compatibility Categories • Mass - What kinetic energy is involved? • Stiffness - How strong is the structure? • Structural Interaction - How does the structure respond with the crash partner’s structures?

Question 33

Explain the compatibility problem.

Answer 33

Question 34

if the mass ratio of two colliding vehicles is 2:1, how large is the fatality risk for occupants in the smaller vehicles.

Answer 34

Question 35

Explain Force Level Compatibility.

Answer 35

Question 36

Explain Stiffness compatibility.

Answer 36

Question 37

Describe Fixed Barrier Crash Test Problem (1).

Answer 37

Question 38

Explain Fixed Barrier Crash Test Problem (2).

Answer 38

Question 39

Describe the GS diagrams.

Answer 39

Question 40

How to calculate vehicle stiffness?

Answer 40

Question 41

Describe vehicle deceleration and deformation.

Answer 41

Question 42

Describe Structural Interaction.

Answer 42

Structural Interaction • Can the structures absorb the energy in an effective manner • Self protection parameter • Pole impacts, offset impacts

Question 43

What will happen?

Answer 43

Question 44

Explain the concept of alignment in car-to-car crash.

Answer 44

Question 45

Explain C3 deformation for mis-aligned situations?

Answer 45

Question 46

In frontal crashes, compatibility is influenced by:

Answer 46

In frontal crashes, compatibility is influenced by: – Vehicle mass (which influences stiffness) – Structural interaction – Compartment strength is a prerequisite. • Fixed barrier tests create mass dependency • Vehicle “Stiffness” measured in barrier tests is not necessarily the same in a vehicle-vehicle crash

Question 47

How can we get vehicles to interact?

Answer 47

Question 48

Explain physical deformable barrier.

Answer 48

Question 49

Explain progressive deformable barrier.

Answer 49

Question 50

Dimensions in Front and Side impact.

Answer 50

Question 51

Explain challenges with side impact.

Answer 51

Question 52

What are common injuries for side impact? What about restraints?

Answer 52

Question 53

Explain ECER95.

Answer 53

Question 54

Explain the moving deformable barrier

Answer 54

Question 55

How is Delta-v defined?

Answer 55

Delta-v=v\_after-v\_before

Question 56

Describe Side Impact Design.

Answer 56

Question 57

Geometry for car in side structure.

Answer 57

Question 58

Describe deformation mode in side impact.

Answer 58

Question 59

Occupant kinematic behavior in side impact?

Answer 59

Question 60

Velocity Time History Side Impact.

Answer 60

Question 61

Displacement in Velocity-Time History.

Answer 61

Question 62

Elaborate on Door Padding Side Impact.

Answer 62

Question 63

Compatibility modes for side impact?

Answer 63

Question 64

Most important notes on side impact.

Answer 64

Side Impact less sensitive to mass and stiffness –Already huge difference in stiffness for front and side structures • Most critical issue is the geometry of the impacting vehicle –Important to not load high on the vehicle side –Reduce intrusion and intrusion velocity on occupant

Question 65

Most common crash types?

Answer 65

Rear-crashes

Question 66

Rear Impacts.

Answer 66

Rear Impacts • The most common crash type producing injuries • Not necessarily the most severe crash type encountered – Relative speed at impact can be lower than travel speed of striking vehicle • Historic main feature for rear impact it protection of fuel system

Question 67

Span of impact energies?

Answer 67

Question 68

Describe Front Component Pedestrian Impact.

Answer 68

Question 69

Describe Sensitivity to Bullet Mass.

Answer 69