1、Tire Forensic Investigation Analyzing Tire Failure Thomas R. GiapponiTire Forensic Investigation Analyzing Tire FailureOther SAE titles of interest: Tire and Vehicle Dynamics, Second Edition By Hans B. Pacejka (Product Code: R-372) The Racing phone (724) 776-4970; fax (724) 776-0790; e-mail Customer
2、Servicesae.org; website http:/store.sae.org.Tire Forensic Investigation Analyzing Tire Failure Thomas R. Giapponi Warrendale, Pa. Copyright 2008 SAE International eISBN: 978-0-7680-3716-6 All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted
3、, in any form or by any means, electronic, mechanical, photo- copying, recording, or otherwise, without the prior written permission of SAE. For permission and licensing requests, contact: SAE Permissions 400 Commonwealth Drive Warrendale, PA 15096-0001 USA E-mail: permissionssae.org Tel: 724-772-40
4、28 Fax: 724-772-4891 Library of Congress Cataloging-in-Publication Data Giapponi, Thomas R. Tire forensic investigation : analyzing tire failure / Thomas R. Giapponi. p. cm. Includes bibliographical references and index. ISBN 978-0-7680-1955-1 1. Automobiles-TiresTesting. 2. Machine parts-Failures.
5、3. Forensic engineering. I. Title. TL270.G53 2008 629.2826-dc22 2008010119 SAE International 400 Commonwealth Drive Warrendale, PA 15096-0001 USA E-mail: CustomerServicesae.org Tel: Fax: 877-606-7323 (inside USA and Canada) 724-776-4970 (outside USA) 724-776-1615 Copyright 2008 SAE International ISB
6、N 978-0-7680-1955-1 SAE Order No. R-387 Printed in the United States of America. green press INITIATIVE SAE International is committed to preserving ancient forests and natural resources. We elected to print this title on 30% post consumer recycled paper, processed chlorine free. As a result, for th
7、is printing, we have saved: 4 Trees (40 tall and 6-8“ diameter) 1,306 Gallons of Wastewater 2 million BTUs of Total Energy 168 Pounds of Solid Waste 315 Pounds of Greenhouse Gases SAE International made this paper choice because our printer, Thomson-Shore, Inc., is a member of Green Press Initiative
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9、alculator. For more information visit: www papercalculator.org.To my daughter, who inspires me, and to my wife, who encouraged me, not only in life, but to actually sit down and write this book.Acknowledgments I would like to thank all those people within SAE International who aided me in writing th
10、is book, including all those who did so anonymously through the SAE peer review process. In addition, I would like to give special thanks to Dr. William Van Ooij from the University of Cincinnati for his review of Section 9.1 of Chapter 9, and to Dr. James Rancourt of Polymer Solutions Inc. of Black
11、sburg, Virginia, for his guidance in the limited amount of chemistry that is included in the book. Without the help of all these individuals, this book would be less than it is.Contents Foreword xv Preface xix Chapter 1 Belt Separation 1 1.1 Belt-to-Belt Separation (or Belt Separation) Discussion 1
12、1.2 Belt SeparationCrack Initiation and Propagation 3 1.3 Root Causes of and Contributors to Belt Separation 6 1.3.1 Over-Deflection 6 1.3.2 High Speed 7 1.3.3 High Ambient and Pavement Temperatures 8 1.3.4 Road Hazards (Impacts) 8 1.3.5 Ozone Deterioration 9 1.3.6 Physiological Damage 9 1.3.7 Unrep
13、aired or Improperly Repaired Punctures . 10 1.3.8 Improper Tire Maintenance 10 1.3.9 Vehicle-Related Conditions 11 1.3.10 Mounting and/or Demounting Damage 11 1.3.11 Poor Storage of Tires 11 1.3.12 Cuts, Snags, Gouges, Tears, and Abrasions 12 1.3.13 Penetrations 12 1.3.14 Manufacturing and Design Co
14、nditions 13X Tire Forensic Investigation Chapter 2 Belt Separation Identification 15 2.1 Tread and Belt Are Detached 15 2.1.1 Belt Detachment Characteristics 19 2.1.2 Belt Stock Degradation 21 2.1.3 Road Rash 21 2.2 Intact Top Belt and Tread 23 2.3 Accelerated WearUnderlying Separation 29 2.4 Belt S
15、eparationAdditional Notes 33 Chapter 3 Other Types of Belt Separation 35 3.1 Belt Edge Separation 35 3.2 Incipient Belt Edge Separation 37 3.3 Atypical Belt Separation 37 Chapter 4 Identification of Causes and Contributors to Belt Separation 39 4.1 Punctures 39 4.1.1 Over-Deflection 46 4.1.2 Intra-C
16、arcass Pressurization 47 4.1.3 Water and Salt Corrosion 53 4.1.4 Breakage of Belt Wires 55 4.2 Over-Deflection 56 4.2.1 Observation of the Compression Groove 56 4.2.2 Wrinkling of the Innerliner 58 4.2.3 Innerliner Color or Discoloration 58 4.2.4 Exterior Sidewall Contact with the Road Surface 59 4.
17、2.5 Observation of the Tread Shoulders 60 4.2.6 Wheel Weight Clip Mark Depth 61 4.2.7 Shifting or Chattering of the Balance Weight Mark 63Contents xi 4.2.8 Interior (Liner Side) of the Bead Toe Creased or Cracked 64 4.2.9 Bead Face Abrasion or a Circumferential Line in the Bead Face 66 4.2.10 Creasi
18、ng of the Base Radii of the Tread Grooves 66 4.3 Penetrations 67 4.3.1 Tread Attached to the Casing 67 4.3.2 Tread and Top Belt Detached 70 4.4 Impacts 73 4.4.1 Identification of Road Hazard Impacts 76 4.4.2 Identification of Belt Separation Due to Impact 81 4.5 Ozone Deterioration 88 4.6 Mounting a
19、nd/or Demounting Damage 93 4.7 Physiological Aging 98 4.7.1 Durometer 98 4.7.2 Appearance and Feel 99 4.7.3 Spot Ozone Damage 100 4.7.4 Belt Tearing 101 4.8 Snags, Gouges, Cuts, Tears, and Abrasions 102 4.9 Cutting and Chipping 104 4.10 Poor Tire Storage and Improper Tire Maintenance 106 4.10.1 Poor
20、 Tire Storage 106 4.10.2 Improper Tire Maintenance 107 4.11 High Speed and High Ambient and/or Pavement Temperatures 108 4.11.1 High Speed 108 4.11.2 High Ambient and/or Pavement Temperatures 109 4.12 Vehicle-Related Conditions 109xii Tire Forensic Investigation Chapter 5 Identification of Non-Belt
21、Separations 111 5.1 Tread Separation 111 5.2 Bead Area Separation 112 5.2.1 Lower Sidewall Compound Separation Off the Plies 114 5.2.2 Separation Between the Ply Turn-Up(s) or Turn-Down(s) 114 5.2.3 Separation of the Bead Wires or Bundle from the Surrounding Plies 115 5.2.4 Separation Between the St
22、eel or Fabric Chipper or Chafer 115 5.2.5 Bead Breaks 116 5.3 Sidewall Separation 117 5.3.1 Separation Between the Plies 117 5.3.2 Separation Between the Sidewall Compound Components 118 5.3.3 Separation Between the Ply and the Sidewall Compound 118 Chapter 6 Identification of Various Tire Condition
23、s 119 6.1 Run-Flat Damage 119 6.2 Chemical Damage to the Tread and Sidewall 124 6.3 Non-Ozone-Related Cracking, Indentations, and Bulges 125 6.3.1 Cracking 125 6.3.2 Indentations 126 6.3.3 Bulges 129 6.4 Identification of Innerliner Conditions 130 6.4.1 Appearance of a Lap Splice 130 6.4.2 Appearanc
24、e of a Butt Splice 131 6.4.3 Liner Tags 132Contents xiii 6.4.4 Liner Openings 132 6.4.5 Ply Cord Shadowing in the Liner 134 Chapter 7 Identification and Significance of Balance Weight Marks 137 Chapter 8 Location of the Tire on a Vehicle 145 8.1 Outboard Side Versus Inboard Side 145 8.2 Rear Positio
25、n Versus Front Position 147 8.2.1 Rear Position 147 8.2.2 Front Position 148 8.3 Left Side Versus Right Side of the Vehicle 149 Chapter 9 Addressing Several Failure Theories 151 9.1 Brassy Wire Failure 151 9.1.1 No Bonding Between the Brass Laminate and the Belt Compound 152 9.1.2 Partial Bonding Be
26、tween the Brass Laminate and the Belt Compound 152 9.1.3 Proper Bonding and Brassy Wire Appearance 153 9.2 Manufacturing Imprints“Liner Marks“ 154 9.3 Nylon Overlay 156 Chapter 10 Visual and Tactile Nondestructive Tire Investigation Techniques 159 10.1 Basic Inspection Process 159 10.2 Marking the T
27、ire for Inspection 161 10.3 Examination ProcessNotes and Photographs 163 10.4 Tactile and Visual Inspection of the Tire 165 10.4.1 Serial Side Sidewall 165xiv Tire Forensic Investigation 10.4.2 Beads 166 10.4.3 Opposite Serial Side Sidewall 167 10.4.4 Tread 167 10.4.5 Belts 168 10.5 Inspection Proce
28、dureDemounting a Tire from the Wheel 169 10.6 Wheel Inspection 170 10.7 Matching the Wheel to the Tire 174 10.8 Identifying Multiple Past Tire Balances 176 10.9 Photography 177 Appendix A References 179 Appendix B Terms 185 Appendix C Compression Groove 197 Appendix D Run-Flat Sequence 203 Appendix
29、E Shell Rating Scale for Ozone Deterioration 209 Index 211 About the Author 217Foreword Tire forensics is the methodical analysis of failed tires in the pursuit of and the identification of the cause(s) or root cause(s) of the disablement of a tire. A com- bination of science, experience, and some a
30、rt goes into the research and analysis of a tire failure. By using the laws of physics, math, chemistry, and engineering, mixed with the experts real-world tire background and experience in the design, testing, and tire development and manufacturing processes, tire forensic experts determine the mos
31、t likely events that led up to and caused the tire to fail. Unlike a forensic pathologist analyzing a body in a criminal case, a failed tire in a civil suit typically is considered evidence that cannot be dissected and destructively analyzed without agreement by all sides. The analysis by the tire e
32、xpert also may not occur until years later, with a chain of custody that may or may not be tidy and with storage conditions that can be less than optimal. Given these conditions, the forensic tire experts background, knowledge, and ability to determine pre-, during, or post-accident damage can be cr
33、ucial to determining failure causation. The same sidewall that will cut and tear during a curb scuff event can impact a road hazard to bend the wheel flange backwards and show relatively little damage on the exterior of the tire. It takes a trained eye working in a systematic fashion to find the unu
34、sual detail that leads to the root cause contributors to the failure. I say “root cause“ because the type of failure should not be the end result of the investigators work. It usually is the beginning. The goal of the tire forensic expert is to keep digging backwards, looking for root cause(s) and p
35、utting as much of the tire story together as possible. In this book, I cover the many ways that a tire can fail and how to identify that failure. However, I will not be going into anything but minor depth in several sections on defectively manufactured tires. It is my opinion that an expert tire for
36、ensic investigator looking into manufacturing or design defects requires knowl- edge of not only tire failure mechanics, but also a solid grounding in several areas such as tire manufacturing, tire mechanics, testing, and tire design, as well as some familiarity with quality control parameters. The
37、total range of parameters,xvi Tire Forensic Investigation how all the various pieces are supposed to fit and operate together, and what are the correct or incorrect manufacturing details in a tire will contain subtleties and nuances; thus, at times, only experience can dictate the outcome. These sub
38、tle- ties will make each tire its own case with particular circumstances and therefore will be covered only generally here. However, while the tire forensic expert is performing the inspection, he or she must always examine the tire with an open mind, looking for all possibilities of failure modes,
39、including an improperly manufactured tire or a badly designed tire. The terms “accident sequence,“ “pre-accident,“ and “post-accident“ are used frequently in this book. Most tire failures do not result in vehicle damage, col- lisions, rollovers, and so forth. However, litigation-related tire failure
40、s tend to involve at least some vehicle damage. By using these terms, I am relating the tire conditions that are seen to the sequence of events after tire disablement, whether or not vehicle damage or an accident has occurred. In nearly all of the text, I discuss passenger car and light truck tires
41、with two-belt systems. There is passing mention of other belting structures, as well as medium/ heavy truck tires. However, when the #1 or #2 belt is mentioned specifically, it is in the context of a two-belt tire. In this book, when I mention root causes, it is not with the intent to gloss over the
42、 fact that, by definition, there cannot be multiple root causes. However, in tire forensics, considering damage factors to the tire during the accident sequence, sullied chains of custody, and other factors, it will not be unusual for the expert to opine that more than one reason caused the tire dis
43、ablement and to determine that one and only one cause is simply not possible. This book will not cover the following items: An overview of general tire basics or basic tire mechanics is not included. The list of references in Appendix A covers basic tire mechanics in depth. I assume the reader alrea
44、dy has a basic understanding of the tire. This book provides the tire expert a compilation of the latest references on various subjects and serves as a reference itself. All possibilities of failure combinations or of what can be seen or photographed in the examination of a tire are not included. Th
45、ere can be details that can merge to bring out the correct causation, and at times, that subtle grouping and the nuances that come with it will come from the experts background. The root causes of tire failure can involve chemistry and chemical forensic analysis of the tire. If this kind of analysis
46、 and information is required, thenForeword xvii expert advice in those areas should be sought. This type of analysis is beyond the scope of this book. The photographs within this book are not in any way meant to cover the range of possibilities of the various appearances of tire forensic examination
47、 points. They are examples intended only to help the reader with the discussion topic at hand. What will be covered in this book are the methodical, physical, visual, and tactile examination of failed tires, a discussion and identification of the various failure modes for passenger car and light tru
48、ck-type tires, and how to determine some of the past history of a tire. Interspersed among various factors, I will share what general wisdom I have learned in 30 years in the tire industry. My apologies to anyone who is unfamiliar with the terms used in this book because those terms tend to vary amo
49、ng those of us from different tire backgrounds. Appendix B provides definitions of terms as an aid to readers. Finally, please read all the footnotes. These important footnotes add information to the text or indicate exceptions; however, they serve only as guide posts and are not meant to be all encompassing in all situations. Although specific page numbers are listed with the cited references scattered throughout this book, these references provide a great deal of general support and knowledge to tire forensics and tire failure analysis.Preface Many years ago w
