Vehicle Collision Dynamics: Analysis and Reconstruction

Cover
Dedication
Contents
Preface
Acknowledgment
1 Structural behavior of the vehicle during the impact
	1.1 Crashworthiness structures and phenomenological aspects of the impact
	1.2 Pulse acceleration curve
		1.2.1 Centroid time
	1.3 Force–deformation curve
	1.4 Distribution of the impact forces over time and space
	1.5 Parameters of influence for the force–deformation curves
		1.5.1 Vehicle model
		1.5.2 Offset
		1.5.3 Oblique impact
		1.5.4 Underride/override
		1.5.5 Impact speed
	References
2 Impact impulsive models
	2.1 Impact models
	2.2 Contact plane, center of impact
	2.3 Momentum, impulse, and friction coefficient
	2.4 Coefficient of restitution
		2.4.1 Closing speed
		2.4.2 Mass effect
		2.4.3 Structural aspects
	2.5 Centered and oblique impacts
	2.6 Model with three degrees of freedom
		2.6.1 Full and sliding impact
		2.6.2 Coefficient of restitution at the center of impact
		2.6.3 Directions of pre- and postimpact speeds
		2.6.4 Impact against a rigid barrier
	2.7 Sensitivity analysis
	2.8 Energy
		2.8.1 Energy and Kelvin’s theorem
			Compression phase
			Restitution phase
			Kelvin’s theorem
		2.8.2 Normal and tangential dissipated energy
	2.9 Scalar equations
	2.10 Speed change in the center of the impact
	2.11 Constant acceleration circle
	References
	Further reading
3 Models for the structural vehicle behavior
	3.1 Lumped mass models
		3.1.1 Mass–spring model (Campbell model)
			Vehicle-to-barrier impact
			Vehicle-to-vehicle impact, effective mass system
			Coefficient of restitution in the collision between two vehicles
		3.1.2 McHenry model
		3.1.3 Kelvin model
			Vehicle-to-barrier Kelvin model
			Responses of an underdamped systems
			Kelvin model parameters identification
			Vehicle-to-vehicle Kelvin model
	3.2 Pulse models
		3.2.1 Halfsine pulse shape
		3.2.2 Haversine pulse shape
		3.2.3 Triangular pulse shape
		3.2.4 Macmillan model
		3.2.5 Example
	3.3 Direct integration of the curves F(x)
	3.4 Reduced order lumped mass model
		3.4.1 Model description
			Contact identification
			Plane of impact and impulse direction
			Directly connected nodes identification
			Calculation of impact forces
			Calculation of final kinematic parameters
	References
4 Energy loss
	4.1 The classical approach to estimate the energy loss
	4.2 Correction for oblique impacts
		4.2.1 Measurement of deformation depths
	4.3 Determination of A and B stiffness coefficients from the residual crush
		4.3.1 Crash against fix rigid barrier
		4.3.2 Crash against a mobile rigid barrier
		4.3.3 Oblique crash against fix rigid barrier
	4.4 Determination of A and B stiffness coefficients from dynamic deformation
	4.5 Energy equivalent speed
	4.6 Triangle method
	4.7 Triangle method with dynamic deformations
	References
5 Crash analysis and reconstruction
	5.1 Crash analysis
		5.1.1 Impact configuration
		5.1.2 Center of impact and contact plan
		5.1.3 Principal direction of forces
		5.1.4 Postimpact phase analysis
		5.1.5 Energy loss evaluation
		5.1.6 Preimpact velocity calculation
		5.1.7 Results check
			Check 1—momentum conservation
			Check 2—compatibility between pre- and postimpact velocities
			Check 3—energy conservation
	5.2 Example
		5.2.1 Impact configuration and point of impact
		5.2.2 Center of impact an contact plane
		5.2.3 Principal direction of forces evaluation
		5.2.4 Postimpact analysis
		5.2.5 Energy loss calculation
			Measurement of the extent of deformations
			Energy equivalent speed evaluation by case comparison
		5.2.6 Preimpact velocity calculation using the method based on momentum calculation
			Results check
		5.2.7 Preimpact speed calculation based on deformations measurements
			Results check
		5.2.8 Velocities from the video analysis
	References
Index