Automotive Accident Reconstruction: Practices and Principles

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Struble, D.: Automotive Accident Reconstruction: Practices and Principles, CRC Press. 1. Auflage 2013. 498 Seiten ISBN 978-1466588370


Automotive Accident Reconstruction: Practices and Principles introduces techniques for gathering information and interpreting evidence, and presents computer-based tools for analyzing crashes. This book provides theory, information and data sources, techniques of investigation, an interpretation of physical evidence, and practical tips for beginners. It also works as an ongoing reference for experienced reconstructionists. The book emphasizes three things: the theoretical foundation, the presentation of data sources, and the computer programs and spread sheets used to apply both theory and collected data in the reconstruction of actual crashes.

It discusses the specific requirements of reconstructing rollover crashes, offers background in structural mechanics, and describes how structural mechanics and impact mechanics are applied to automobiles that crash. The text explores the treatment of crush energy when vehicles collide with each other and with fixed objects. It delves into various classes of crashes, and simulation models. The framework of the book starts backward in time, beginning with the analysis of post-crash vehicle motions that occurred without driver control.

Applies time-reverse methods, in a detailed and rigorous way, to vehicle run-out trajectories, utilizing the available physical evidence Walks the reader through a collection of digital crash test data from public sources, with detailed instructions on how to process and filter the information Shows the reader how to build spread sheets detailing calculations involving crush energy and vehicle post-crash trajectory characteristics Contains a comprehensive treatment of crush energy

This text can also serve as a resource for industry professionals, particularly with regard to the underlying physics.


1. General Principles

An Exact Science?
Units, Dimensions, Accuracy, Precision, and Significant Figures
Newton’s Laws of Motion
Coordinate Systems
Accident Phases
Conservation Laws
Crush Zones
Acceleration, Velocity, and Displacement
Crash Severity Measures
The Concept of Equivalence
Objectives of Accident Reconstruction
Forward-Looking Models (Simulations)
Backward-Looking Methods

2. Tire Models

Rolling Resistance
Longitudinal Force Generation
Lateral Force Generation
Longitudinal and Lateral Forces Together
The Backward-Looking Approach
Effects of Crab Angle

3. Subdividing Noncollision Trajectories with Splines

Selecting an Independent Variable
Finding a Smoothing Function
Properties of Splines
Example of Using a Spline for a Trajectory

4. A Program for Reverse Trajectory Calculation Using Splines

Developing Velocity–Time Histories for Vehicle Run-Out Trajectories
Other Variables at Play in Reverse Trajectory Calculations
Vehicle Headings and Yaw Rates
Example Reverse Trajectory Calculation
Yaw Rates
Secondary Impacts with Fixed Objects
Verifying Methods of Analyzing Post-Crash Trajectories
The RICSAC Crash Tests
Documenting the Run-Out Motions
Data Acquisition and Processing Issues
Separation Positions for the RICSAC Run-Out Trajectories
Side Slap Impacts
Secondary Impacts and Controlled Rest
Surface Friction
Sample Validation Run
Results of Reverse Trajectory Validation

5. Time–Distance Studies

Perception and Reaction
Constant Acceleration
Example of Constant Acceleration Time–Distance Study
Variable Acceleration

6. Vehicle Data Sources for the Accident Reconstructionist

Nomenclature and Terminology
Vehicle Identification Numbers
Vehicle Specifications and Market Data
Vehicle Inertial Properties
Production Change-Overs and Model Runs
Sisters and Clones
Other Information Sources
People Sizes

7. Accident Investigation

Information Gathering
Scene Inspection
Vehicle Inspection
Crush Measurement

8. Getting Information from Photographs

Photographic Analysis
Mathematical Basis of Photogrammetry
Two-Dimensional Photogrammetry
Camera Reverse Projection Methods
Two-Photograph Camera Reverse Projection
Analytical Reverse Projection
Three-Dimensional Multiple-Image Photogrammetry

9. Filtering Impulse Data

Background and Theory
Analog Filters
Filter Order
Bode Plots
Filter Types
Digital Filters
FIR Filters
IIR Filters
Use of the Z-transform
Example of Finding the Difference Equation from the Transfer Function
Bilinear Transforms

10. Digital Filters for Airbag Applications

Example of Digital Filter in Airbag Sensor

11. Obtaining NHTSA Crash Test Data

Contemplating Vehicle Crashes
The Crush Zone
Accelerometer Mount Strategy
Other Measurement Parameters and Transducers
Sign Conventions and Coordinate Systems
Processing NHTSA Crash Test Accelerometer Data
Summary of the Process
Downloading Data from NHTSA’s Web Site
Identifying the Accelerometer Channels to be Downloaded
Downloading the Desired Channels
Parsing the Data File
Filtering the Data

12. Processing NHTSA Crash Test Acceleration Data

Integrating the Accelerations
Filtering the Data
Filter( j) Subroutine
Parsing the Data File
NHTFiltr.bas Program Output
Averaging Two Acceleration Channels
Using the NHTSA Signal Browser

13. Analyzing Crash Pulse Data

Data from NHTSA
Repeatability of Digitizing Hardcopy Plots
Effects of Plotted Curve Quality
Accuracy of the Integration Process
Accuracy of the Filtering Process
Effects of Filtering on Acceleration and Velocity Data
Effect of Accelerometer Location on the Crash Pulse

14. Downloading and Analyzing NHTSA Load Cell Barrier Data

The Load Cell Barrier Face
Downloading NHTSA Load Cell Barrier Data
Crash Test Data Files
Grouping Load Cell Data Channels
Computational Burden of Load Cell Data Analysis
Example of Load Cell Barrier Data Analysis
Using the NHTSA Load Cell Analysis Software

15. Rollover Forensics

Measurements of Severity
Evidence on the Vehicle
Evidence at the Scene

16. Rollover Analysis

Use of an Overall Drag Factor
Laying Out the Rollover Trajectory
Setting Up a Reverse Trajectory Spreadsheet
Examining the Yaw and Roll Rates
Scratch Angle Directions
Soil and Curb Trips

17. Vehicle Structure Crash Mechanics

Load Paths
Load–Deflection Curves
Energy Absorption
Structural Dynamics
Restitution Revisited
Small Car Barrier Crashes
Large Car Barrier Crashes
Small Car/Large Car Comparisons
Narrow Fixed Object Collisions
Vehicle-to-Vehicle Collisions
Large Car Hits Small Car
Barrier Equivalence
Load–Deflection Curves from Crash Tests
Measures of Crash Severity

18. Impact Mechanics

Crash Phase Duration
Degrees of Freedom
Mass, Moment of Inertia, Impulse, and Momentum
General Principles of Impulse–Momentum-Based
Impact Mechanics
Eccentric Collisions and Effective Mass
Using Particle Mass Analysis for Eccentric Collisions
Momentum Conservation Using Each Body as a System
The Planar Impact Mechanics Approach
The Collision Safety Engineering Approach
Methods Utilizing the Conservation of Energy

19. Uniaxial Collisions

Conservation of Momentum
Conservation of Energy

20. Momentum Conservation for Central Collisions


21. Assessing the Crush Energy

Constant-Stiffness Models
Sample Form Factor Calculation: Half-Sine Wave Crush Profile
Sample Form Factor Calculation: Half-Sine Wave Squared
Crush Profile
Form Factors for Piecewise-Linear Crush Profiles
Sample Form Factor Calculation: Triangular Crush Profile
Constant-Stiffness Crash Plots
Example Constant-Stiffness Crash Plot
Constant-Stiffness Crash Plots for Uniaxial Impacts by Rigid
Moving Barriers
Segment-by-Segment Analysis of Accident Vehicle Crush
Constant-Stiffness Crash Plots for Repeated Impacts
Constant Stiffness with Force Saturation
Constant Stiffness Model with Force Saturation, Using Piecewise
Linear Crush Profiles
Constant-Force Model
Constant-Force Model with Piecewise Linear Crush Profiles
Structural Stiffness Parameters: Make or Buy?

22. Measuring Vehicle Crush

NASS Protocol
Full-Scale Mapping
Total Station Method
Loose Parts
Other Crush Measurement Issues in Coplanar Crashes
Rollover Roof Deformation Measurements

23. Reconstructing Coplanar Collisions, Including Energy Dissipation

General Approach
Development of the Governing Equations
The Physical Meaning of Two Roots
Extra Information
Sample Reconstruction

24. Checking the Results in Coplanar Collision Analysis

Sample Spreadsheet Calculations
Choice of Roots
Crash Duration
Selecting Which Vehicle is Number 1
Yaw Rate Degradation
Yaw Rates at Impact
Trajectory Data
Vehicle Center of Mass Positions
Impact Configuration Estimate
Vehicle Headings at Impact
Crab Angles at Impact
Approach Angles
Restitution Coefficient
Principal Directions of Force
Energy Conservation
Momentum Conservation
Direction of Momentum Vector
Momentum, Crush Energy, Closing Velocity, and Impact Velocities
Angular Momentum
Force Balance
Vehicle Inputs
Final Remarks

25. Narrow Fixed-Object Collisions

Wooden Utility Poles
Poles that Move
Crush Profiles and Vehicle Crush Energy
Maximum Crush and Impact Speed
Side Impacts

26. Underride/Override Collisions

NHTSA Underride Guard Crash Testing
Synectics Bumper Underride Crash Tests
Analyzing Crush in Full-Width and Offset Override Tests
The NHTSA Tests Revisited
More Taurus Underride Tests
Using Load Cell Barrier Information
Shear Energy in Underride Crashes
Reconstructing Ford Taurus Underride Crashes
Reconstructing Honda Accord Underride Crashes
Reconstructing the Plymouth Reliant Underride Crash

27. Simulations and Other Computer Programs

CRASH Family of Programs
SMAC Family of Programs
Noncollision Simulations
Occupant Models



<pr>Catalog no. K20381

October 2013

c. 488 pp.

ISBN: 978-1-4665-8837-0

$149.95 / £95.00

Contact Editor: Jonathan Plant


Reconstruction Crush energy Velocity change (delta-V) Rollovers Conservation of energy Conservation of momentum Newton’s Second Law Trajectory analysis Structural stiffness Restitution Filters, digital Planar impacts Impact velocity Vehicle crashes Crash tests Photogrammetry Time-reverse Drag factor Pole impacts Underride crashes