Automotive Accident Reconstruction: Practices and Principles, Second Edition, 2nd Edition (Hardback) book cover

Automotive Accident Reconstruction

Practices and Principles, Second Edition, 2nd Edition

By Donald E. Struble, John D. Struble

CRC Press

426 pages | 143 B/W Illus.

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Hardback: 9780367415839
pub: 2020-01-30
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Description

This fully updated edition presents practices and principles applicable for the reconstruction of automobile and commercial truck crashes. Like the First Edition, it starts at the very beginning with fundamental principles, information sources, and data gathering and inspection techniques for accident scenes and vehicles. It goes on to show how to analyze photographs and crash test data. The book presents tire fundamentals and shows how to use them in spreadsheet-based reverse-trajectory analysis. Such methods are also applied to reconstructing rollover crashes. Impacts with narrow fixed objects are discussed. Impact mechanics, structural dynamics, and conservation-based reconstruction methods are presented. The book contains a comprehensive treatment of crush energy, and how to develop structural stiffness properties from crash test data. Computer simulations are reviewed and discussed.

Extensively revised, this edition contains new material on side pole impacts. It has entirely new chapters devoted to low-speed impacts, downloading electronic data from vehicles, deriving structural stiffness in side impacts, and incorporating electronic data into accident reconstructions.

Table of Contents

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

References

2. Tire models

Rolling Resistance

Longitudinal Force Generation

Lateral Force Generation

Longitudinal and Lateral Forces Together

The Backward-Looking Approach

The Effects of Crab Angle

References

3. Subdividing Non-Collision Trajectories with Splines

Introduction

Selecting an Independent Variable

Finding a Smoothing Function

Properties of Splines

Example of Using a Spline for a Trajectory

References

4. A Program for Reverse Trajectory Calculations Using Splines

Introduction

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

Brake Factors

Sample Validation Run

Results of Reverse Trajectory Validation

References

5. Time-Distance Studies

Purpose

Perception and Reaction

Constant Acceleration

Example of Constant Acceleration Time-Distance Study

Variable Acceleration

References

6. Vehicle Data Sources for the Accident Reconstructionist

Introduction

Nomenclature and Terminology

SAE Standard Dimensions

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

References

7. Accident Investigation

Introduction

Information Gathering

Scene Inspection

Vehicle Inspection

Crush Measurement

Inspection Equipment

References

8. Obtaining Electronic Data from Vehicles

Introduction

Evolution of Electronic Data

Passenger Vehicle EDR Data

Commercial Vehicle ECM Data

Data from Infotainment Systems

GPS and Vehicle Telematics Data

On-Board Video Data

References

9. Getting Information from Photographs

Introduction

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

References

10. Measuring Vehicle Crush

Introduction

NASS Protocol

Full-Scale Mapping

Total Station and Three-Dimensional Scanning Methods

Loose Parts

Other Crush Measurement Issues in Co-Planar Crashes

Rollover Roof Deformation Measurements

References

11. Filtering Impulse Data

Introduction

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

Digital Filters for Airbag Applications

Example of a Digital Filter in an Airbag Sensor

References

12. Obtaining and Using NHTSA Crash Test Data

Contemplating Vehicle Crashes

The Crush Zone

Accelerometer Mount Strategy

Other Measurement Parameters and Transducers

Sign Conventions and Coordinate Systems

Finding NHTSA Crash Test Data

Filtering the Data

Filter(j) Subroutine

Using NHTSA Signal Analysis Software

References

13. Analyzing Crash Pulse Data

Crash Pulses in Hard-Copy Crash Test Reports

Integrating the Accelerations

Repeatability of Digitizing Hard-Copy Plots

Effects of Plotted Curve Quality

Accuracy of the Integration Process

Accuracy of the Filtering Process

Effects of Filtering on Acceleration and Velocity Data

The Effect of Accelerometer Location on the Crash Pulse

Conclusions

References

14. Downloading and Analyzing NHTSA Load Cell Barrier Data

The Load Cell Barrier Face

Downloading NHTSA Load Cell Barrier Data

Grouping Load Cell Data Channels

The Computational Burden of Load Cell Data Analysis

Aliasing

Load Cell Barrier Data Analysis Using NHTSA’s PlotBrowser

References

15. Rollover Investigation

Introduction

Measurements of Severity

Evidence on the Vehicle

Evidence at the Scene

References

16. Rollover Analysis

Introduction

Use of an Overall Drag Factor

Laying Out the Rollover Trajectory

Setting Up a Reverse Trajectory Spread Sheet

Examining the Yaw and Roll Rates

Scratch Angle Directions

Soil and Curb Trips

References

17. Vehicle Structure Crash Dynamics

Introduction

Load Paths

Load-Deflection Curves

Energy Absorption

Restitution

Structural Dynamics

Restitution Revisited

Small Car Barrier Crashes

Large Car Barrier Crashes

Small Car/Large Car Comparisons

Narrow Fixed Object Comparisons

Vehicle to Vehicle Collisions

Large Car Hits Small Car

Barrier Equivalence

Load-Deflection Curves from Crash Tests

Measures of Crash Severity

References

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

Impulse-Momentum Using Each Body as a System

The Planar Impact Mechanics Approach

The Collision Safety Engineering Approach

Methods Utilizing the Conservation of Energy

References

19. Reconstruction Using Conservation of Momentum and Energy

Uniaxial Collisions

Conservation of Momentum

Conservation of Energy

Momentum Conservation for Two-Degree-of-Freedom Co-planar Collisions

References

20. Constant-Stiffness Structures and Crash Plots

Introduction

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

References

21. Crush Energy in Accident Vehicles and Non-Linear Structures

Introduction

Segment-By-Segment Analysis of Accident Vehicle Crush Profiles

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?

References

22. Structural Stiffness in Side Impacts

Introduction

MDB Stiffness Characteristics

Kinetic Energies at Separation

The Need for a Calculation Methodology for Deriving Stiffness Parameters

Open-source Methods for Stiffness Evaluation

Insights from Repeated Side Impacts

Conclusions

References

23. Narrow Fixed-Object Collisions

Introduction

Wooden Utility Poles

Poles that Move

Crush Profiles and Vehicle Crush Energy

Maximum Crush and Impact Speed

Side Pole Impacts

References

24. Crush Energy in Underride/Override Collisions

Introduction

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 Civic Underride Crashes

Reconstructing the Plymouth Reliant Underride Crash

Conclusions

References

25. Low-Speed Impacts

Introduction

Braking Forces During Rear Impacts

Low-Speed Side Impacts

Tire Scrub in Side Impact Tests of 2013-2014 Honda Accords

Characterizing Structures and Assessing Crush Energy at Low Speeds

Use of Repair Cost Information for Low-Speed Crashes

References

26. Reconstructing Co-Planar Collisions, Including Energy Dissipation

General Approach

Development of the Governing Equations

The Physical Meaning of Two Roots

Extra Information

Sample Reconstruction

Relative Speeds and Restitution Coefficient

Vehicle Center of Mass Positions

Vehicle Angles at Impact

Principal Direction of Force

Conservation Laws

References

27. Checking the Results in Co-Planar Collision Analysis

Introduction

Sample Spreadsheet Calculations

Choice of Roots

Crash Duration

Selecting Which Vehicle is Number 1

Yaw Rate Degradation

Yaw Rates at Impact

Trajectory Data

Impact Configuration Estimate

Vehicle Angles at Impact

Crab Angles at Impact

Approach Angles

Restitution Coefficient

References

28. Incorporating Electronic Data into Accident Reconstructions

Introduction

Data from EDR

Data from GPS

References

29. Simulation Models and Other Computer Programs

Introduction

CRASH Family of Programs

SMAC Family of Programs

PC-CRASH

Non-Collision Simulations

Occupant Models

References

About the Authors

Donald E. Struble holds BS, MS, and PhD degrees from California Polytechnic State University, Stanford University, and Georgia Institute of Technology, respectively, all in engineering with an emphasis on structural mechanics. Dr. Struble has worked in automotive crashworthiness since 1972, and accident reconstruction since 1983. He is co-holder of a patent on side impact air bags, and was editor of Advances in Side Airbag Systems, published by SAE International in 2005. He is a member of SAE, AAAM, and Sigma Xi, the Scientific Research Society.

John D. Struble holds a BS and MS in Mechanical Engineering from the University of Arizona and the Georgia Institute of Technology, respectively. Mr. Struble served as a Safety Standards Engineer for the National Highway Traffic Safety Administration and Senior Engineer at Struble-Welsh Engineering prior to joining Exponent, Inc., where he is a Principal in the Vehicle Engineering Practice.

About the Series

Ground Vehicle Engineering

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Subject Categories

BISAC Subject Codes/Headings:
TEC009020
TECHNOLOGY & ENGINEERING / Civil / General
TEC009070
TECHNOLOGY & ENGINEERING / Mechanical
TEC017000
TECHNOLOGY & ENGINEERING / Industrial Health & Safety