Forensic Engineering:: The Art and Craft of A Failure Detective

421 Pages·2020·17.911 MB·English

by  Colin Gagg

Forensic Engineering
Te Art and Craf of a Failure Detective

Forensic Engineering
Te Art and Craf of a Failure Detective
Colin R. Gagg
CRC Press
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Contents
Preface xix
Acknowledgements xxiii
Author xxv
1 Failure Analysis or Forensic Engineering? 1
1.0 Synopsis 1
1.1 Historic Failure Analysis 2
1.2 Conventional Failure Analysis 4
1.3 Product Defects 9
1.4 Causal Analysis 10
1.4.1 Qualitative Analysis 11
1.4.2 Semi-Quantitative Analysis 11
1.4.3 Computer-Aided Causal Analysis 13
1.4.5 Case Study: Failure of a 4.5-inch Kitchen Knife 14
1.5 Design Calculations and Modelling 15
1.5.1 Miner’s Law for Life-Time Cumulative Damage
Prediction 16
1.6 Summation of Conventional Failure Analysis 17
1.7 Forensic Engineering 18
1.7.1 Case Study: Collapse of the Rana Plaza Factory 18
1.8 Range of Competence 20
1.8.1 A Generic Failure Analysis or a Forensic
Investigation? 21
1.9 Initial Forensic Approach to Failure 21
1.9.1 Reverse Engineering (Te ‘Weakest-Link’
Principle) 22
1.9.2 Associated Costs of Forensic Investigation 23
1.10 Historic Failures 23
1.10.1 Computer-Aided Technology Limitations 27
1.11 Analytical Techniques 31
1.12 Dissemination of Knowledge and Experience 32
1.12.1 Popular Books 33
1.12.2 Event Reporting 34
1.12.3 Textbooks 37
1.12.4 Forensic Engineering Teaching 38
vii
viii Contents
1.13 Case Study Temes 39
1.13.1 Te Sayano-Shushenskaya Power Station
Accident of 2009 39
1.14 Research-Enriched Teaching 40
1.15 Concluding Remarks 41
References 42
2 Initial Aspects of Forensic Failure Investigation 51
2.0 Introduction 51
2.1 Tree Essential ‘Abstract’ Assets for the Investigator 52
2.1.1 Assessing the Situation 52
2.1.2 Initial Visual Observation as a Fact-Finding
Exercise 52
2.1.3 Te Failure Scenario 52
2.1.4 Summary of Understated Investigative Skills 53
2.2 Visual Observation 54
2.2.1 Case Study: Visual Comparison 55
2.2.2 Case Study: Common (Engineering) Sense 56
2.3 Forensic Photography 57
2.4 Record Keeping 59
2.5 Witness Evidence 60
2.6 Documentary Evidence 61
2.6.1 Case Study: Fatal Aircraf Crash 61
2.7 Product and Material Standards 63
2.7.1 Case Study: Step Ladder Failure 63
2.8 Patents 66
2.9 Surviving Remains (Detritus) 66
2.9.1 Gathering of Evidence and the ‘Chain of Evidence’ 67
2.10 Product Liability 68
2.10.1 Case Study: Premature Failure of a Presentation
Cake Knife 69
2.11 Te ‘Corporate’ Environment 70
2.11.1 Case Study: Bird-Strike Testing of Aircraf Engines 71
2.12 Abuse or Misuse 72
2.12.1 Case Study: Abuse 73
2.12.2 Case Study: Misuse 74
References 77
3 A Framework or Methodology for Forensic
Investigation 79
3.0 Introduction 79
3.1 Background to Failure Analysis Methodology 79
Contents ix
3.2 An Investigative Path Followed by the Writer 80
3.2.1 Intuition (Reasoning) and a ‘Structured’
Investigation Framework 80
3.2.2 Individual Stages of Investigation 81
3.2.3 Te Field Investigation Kit 84
3.2.4 Initial Approach to Failure Investigation 86
3.2.5 Background Data Collection 87
3.2.6 Sifing the Evidence 88
3.2.6.1 Case Study: Failure of a New Design
of Horse Bit 88
3.2.7 Records 89
3.2.8 Single Items of Evidence 89
3.3 Te Failure Detective 91
3.3.1 Transformation Stresses 91
3.3.2 Establishing a Load Transfer Path to Determine
the ‘Weakest Link’ 92
3.3.3 Case Study: Te Weakest-Link Principle 94
3.3.4 Case Study: Failure of a Backhoe Dipper Arm 95
3.4 Computer-Aided Technologies 96
3.4.1 Case Study: Failure of an Open-Ended
Spanner 97
3.5 Te Forensic Engineering Report 100
3.6 Concluding Remarks 101
References 101
4 Analytical Methods 103
4.0 Introduction to a Typical Forensic Engineering
‘Toolbox’ 103
4.1 Non-Destructive Testing (NDT) 104
4.1.1 Case Study: Failure of a Power Transmission
Shaf 105
4.2 Crack Detection and the Human Eye 106
4.2.1 Surface Appearance of Common Cracks 107
4.2.2 Other Crack Detection Techniques 108
4.3 Hardness Testing 111
4.3.1 Case Study: Pin-Punch Splintering 113
4.3.2 Relationship between Hardness and Tensile
Strength 114
4.4 Indirect Stress/Strain Analysis 115
4.4.1 Brittle Lacquer Technique 115
4.4.2 Case Study: Cycling Accident 116
4.4.3 Photoelastic Stress Measurement 117