Forensic Materials Engineering: Case Studies

by Lewis; Peter Rhys

• ISBN13: 9780849311826
• ISBN10: 0849311829
• Edition: 1st
• Format: Hardcover
• Copyright: 2003-09-29
• Publisher: CRC Press

Summary

A catheter used to transfer vital fluids splits during surgery.A wheel detaches from a moving car on the highway.A small gear tooth breaks from a chisel and flies into a mechanic's eye.How did these accidents occur and were they preventable? Peter Lewis, Ken Reynolds, and Colin Gagg are seasoned forensic engineers who have been commissioned by insurance companies, lawyers, and private clients to investigate a variety of mechanical accidents that allegedly involved faulty equipment. The causes of these failures have varied - from manufacturing defects to user negligence to a combination of both - but their outcomes are often the same: huge financial loss, and sometimes even the immeasurable loss of life.Case studies are the most valuable source of information for manufacturers striving to improve their products. In Forensic Materials Engineering: Case Studies, the authors offer stories of real accidents and thorough assessments of what went wrong. Unlike other case study presentations, they focus on not just the technical details, but also other vital aspects, including human error, turning points in the investigations, and the litigation involved. Presented in chronological order, each well-illustrated case study includes legal background, reports the case results, and highlights the lessons learned from the case.New materials and applications appear constantly, and with them, new failure modes. Examining various materials in a range of situations, Forensic Materials Engineering: Case Studies provides an outstanding opportunity to gain virtual experience through up-to-date facts and feedback from forensic engineering practitioners.

Table of Contents

1 Introduction	1	(24)
1.1 Forensic Engineering	1	(2)
1.2 Causal Analysis	3	(4)
1.2.1 Fault Tree Analysis	4	(3)
1.3 Product Design and Manufacture	7	(3)
1.4 Product Defects	10	(2)
1.4.1 Primary Defects	11	(1)
1.4.2 Secondary Defects	12	(1)
1.5 Product Testing	12	(2)
1.5.1 FMEA	13	(1)
1.6 Litigation	14	(7)
1.6.1 Trials of Disputes	15	(2)
1.6.2 Evidence and Trial Procedure	17	(2)
1.6.3 The Role of Forensic Engineers	19	(1)
1.6.4 Expert Reports	20	(1)
1.7 Engineering Materials	21	(1)
References	22	(3)
2 Materials in Distress	25	(36)
2.1 Introduction	25	(5)
2.1.1 Cause of Demise - Engineering example	27	(3)
2.2 Manufacturing Defects	30	(5)
2.2.1 Defects by Omission	31	(2)
2.2.2 Welding Defects	33	(2)
2.3 Failures under Mechanical Overload	35	(8)
2.3.1 Polymeric Materials	39	(2)
2.3.2 Fracture Surfaces	41	(2)
2.4 Fatigue Failure	43	(9)
2.5 Corrosion	52	(6)
2.5.1 Stress Corrosion Cracking of Metals	55	(3)
2.5.2 Environmental Cracking of Plastics	58	(1)
2.6 Creep	58	(3)
3 Establishing the Load Transfer Path	61	(24)
3.1 Loads, Forces and Design	61	(1)
3.2 Abnormal Externally Applied Force -- Stepladder	62	(4)
3.3 Establishing the Load Transfer Path	66	(7)
3.4 Effect of Faults and Weaknesses	73	(3)
3.5 Cause of Failure of Axle Bracket in Racing Motorcycle Sidecar	76	(9)
4 A "Toolbox" for Forensic Engineers	85	(46)
4.1 Introduction	85	(1)
4.2 An Initial Approach to a Failure	86	(3)
4.2.1 Significance of Initial Observations	87	(2)
4.3 Assessing the Situation	89	(1)
4.4 Inside the Toolbox	90	(15)
4.4.1 Photography and Sample Handling	91	(1)
4.4.2 Product and Material Standards	92	(1)
4.4.3 Macroscopic Examination	93	(1)
4.4.4 Examination under Magnification: Optical Microscopic Inspection	94	(1)
4.4.5 Metallographic Sectioning	94	(6)
4.4.6 Scanning Electron Microscopy (SEM)	100	(5)
4.5 Mechanical Testing	105	(10)
4.5.1 Tensile Testing	105	(2)
4.5.2 Hardness Testing	107	(1)
4.5.3 Moh's Hardness Test	107	(1)
4.5.4 Vickers Hardness Test	107	(1)
4.5.5 Brinell Hardness Test	108	(1)
4.5.6 Rockwell Hardness Test	109	(1)
4.5.7 Tensile Strength and Hv	109	(2)
4.5.8 Bend Tests	111	(2)
4.5.9 Torsion Testing	113	(2)
4.6 Indirect Strain Measurement	115	(6)
4.6.1 Brittle Lacquer	115	(2)
4.6.2 Crack Detection Methods	117	(1)
4.6.3 Other Crack Detection Techniques	118	(3)
4.7 Chemical and Thermal Analysis	121	(7)
4.7.1 Differential Scanning Calorimetry (DSC)	121	(3)
4.7.2 Infrared Spectroscopy	124	(2)
4.7.3 Chromatography	126	(1)
4.7.4 Other Methods	127	(1)
4.7.5 Integrity of Analysis	127	(1)
4.8 Closing Comments	128	(2)
References	130	(1)
5 Failure Due to Manufacturing Faults	131	(40)
5.1 Traumatic Failure	131	(2)
5.2 Failure of Freight Containers	133	(11)
5.3 Failures of Gears in Oil Pump	144	(2)
5.4 Manhole Step	146	(5)
5.5 Failure of Threaded Iron Pipe Coupling	151	(1)
5.6 Replacement Gears for Gearbox of Heavy Trucks	152	(3)
5.7 Hooks and Keepers	155	(3)
5.8 Rivet Failure in Multipurpose Tool	158	(1)
5.9 Scaffolding Guard Rail	159	(6)
5.10 Gas Molding Problems	165	(6)
6 Fluid Transport	171	(44)
6.1 Introduction	171	(1)
6.2 Materials of Choice	171	(3)
6.2.1 Design Criteria	172	(1)
6.2.2 Corrosion and Environmental Degradation	172	(1)
6.2.3 Case Studies	173	(1)
6.3 Corrosion Failures	174	(10)
6.3.1 Failure of an Oil Delivery Pipe	175	(2)
6.3.2 Vehicle Brake Pipe Failure	177	(4)
6.3.3 Stainless Steel Pipe Clamp Corrosion	181	(3)
6.3.4 Other SCC Failures	184	(1)
6.4 A Plumbing Problem	184	(10)
6.4.1 Reasons for Failure	186	(1)
6.4.2 The Fracture Surface	187	(2)
6.4.3 Water Pressure	189	(2)
6.4.4 Molding Features	191	(1)
6.4.5 Stress Corrosion Cracking	192	(1)
6.4.6 Acetal Polymer	192	(1)
6.4.7 A U.S. Problem	193	(1)
6.4.8 Aftermath	194	(1)
6.5 Fuel Pipes	194	(5)
6.5.1 Cracking and Abrasion	196	(1)
6.5.2 A Problem in Eire	197	(1)
6.5.3 Murphy Infants v. Fiat Spa	198	(1)
6.5.4 Aftermath	199	(1)
6.6 SCC of Diesel Fuel Pipe Connector	199	(6)
6.6.1 Remains of the Pipe	200	(2)
6.6.2 Stress Corrosion Cracking	202	(2)
6.6.3 Loading of the Return Pipe	204	(1)
6.6.4 Conclusions	204	(1)
6.7 Sealing Materials	205	(7)
6.7.1 Failed Seals	208	(1)
6.7.2 Experimental Analysis	208	(2)
6.7.3 Discussion	210	(2)
6.7.4 Conclusions	212	(1)
References	212	(3)
7 Failure of Storage Vessels	215	(40)
7.1 Leakage of a Galvanized Tank	216	(2)
7.1.1 The Failed Header Tank	217	(1)
7.2 A Radiator Failure	218	(10)
7.2.1 Material Requirements	218	(1)
7.2.2 Failure Investigation	219	(2)
7.2.3 The Critical Crack	221	(2)
7.2.4 Microscopy	223	(3)
7.2.5 Mechanical Tests	226	(1)
7.2.6 Mechanical Analysis	226	(1)
7.2.7 Aftermath	227	(1)
7.3 Battery Case Failures	228	(8)
7.3.1 Miners Backpack Cases	228	(3)
7.3.2 Fire in the Hong Kong Subway	231	(2)
7.3.3 UV Degradation	233	(3)
7.4 Domestic Bathtubs	236	(3)
7.5 Failure of Underground Storage Tanks	239	(2)
7.6 Failure of Large Storage Tanks	241	(12)
7.6.1 The Material Evidence	243	(2)
7.6.2 Subcritical Cracks	245	(2)
7.6.3 Material Testing	247	(1)
7.6.4 Weld Defects	248	(1)
7.6.5 Tank Structure	248	(2)
7.6.6 Aftermath	250	(1)
7.6.7 Inspection of Other Tanks	251	(1)
7.6.8 Other Tank Failures	252	(1)
7.7 Conclusions	253	(1)
References	254	(1)
8 Accidents in the Workplace	255	(32)
8.1 Explosion in a Foundry	255	(6)
8.1.1 The Accident	255	(2)
8.1.2 Investigations	257	(1)
8.1.3 The Pleadings	258	(2)
8.1.4 Outcome	260	(1)
8.2 Accident with a Pressure Die-Casting Machine	261	(3)
8.2.1 The Accident	261	(2)
8.2.2 Outcome	263	(1)
8.3 Eye Injuries	264	(9)
8.3.1 Eye Injury While Replacing Clutch Plate	265	(2)
8.3.2 Lath Axe	267	(3)
8.3.3 Printer's Drying Frame	270	(3)
8.4 Ladder Accidents	273	(13)
8.4.1 The Material Evidence	273	(2)
8.4.2 Ladder Stability	275	(1)
8.4.3 Reconstruction	275	(1)
8.4.4 Coefficient of Friction	276	(1)
8.4.5 Repose Angle	277	(1)
8.4.6 Stability Experiments	278	(3)
8.4.7 Conclusions	281	(1)
8.4.8 Workplace Accident	282	(2)
8.4.9 Ladder Accidents and Design Improvements	284	(2)
References	286	(1)
9 Failure of Medical Implements	287	(32)
9.1 Introduction	287	(1)
9.2 The Body as a working Environment	288	(1)
9.3 Design and Performance Criteria	288	(2)
9.3.1 Performance	289	(1)
9.3.2 Design Attributes	289	(1)
9.4 Hip Joint Failures	290	(7)
9.4.1 Fatigue Failure of Prosthetic Hip Components	290	(2)
9.4.2 Failure in Femoral Stem of Total Hip Prosthesis	292	(1)
9.4.3 Manufacturing Contamination of Acetabular Hip Shells	293	(2)
9.4.4 Corrosion of a Polished Titanium Alloy Femoral Stem	295	(2)
9.5 Catheter Failures	297	(6)
9.5.1 Fracture of a TPE Catheter	297	(1)
9.5.2 Fracture of a Breast Tissue Expander	298	(5)
9.6 Examination of Needle Recovered from Upper Thigh	303	(2)
9.6.1 Outcome	305	(1)
9.7 A Defective Breathing Tube	305	(2)
9.7.1 Outcome	306	(1)
9.8 Failure of Surgical Tweezers	307	(6)
9.8.1 In-Plane Cracking of Surgical Tweezers	307	(3)
9.8.2 Production Failure of Titanium (Ti-6Al-4V) Ophthalmic Tweezers	310	(3)
9.9 A Failed Crutch	313	(2)
9.10 Failure of Nerve Probe during Surgical Procedure	315	(2)
9.10.1 Outcome	316	(1)
References	317	(2)
10 Component Failure in Road Traffic Accidents	319	(30)
10.1 Steering Arm from Truck	320	(8)
10.1.1 The Accident	320	(3)
10.1.2 Investigations	323	(2)
10.1.3 Alternative Explanation	325	(1)
10.1.4 Further Examples of Steering Shaft Failures from Motor Vehicle Accidents	326	(2)
10.2 Wheel Detachments	328	(3)
10.3 Brake Pipe Failures	331	(4)
10.3.1 Brake Failure by Fatigue	332	(3)
10.3.2 Failure of a Plastic Pipe	335	(1)
10.4 Lamp Filaments	335	(5)
10.4.1 Failure Mechanisms	336	(2)
10.4.2 Motorcycle Accident	338	(2)
10.5 Tow Hitches	340	(9)
10.5.1 Trailer Accident	340	(4)
10.5.2 Tow Bolt Fatigue	344	(5)
11 Fraudulent Insurance Claims	349	(16)
11.1 Car Keys	350	(2)
11.2 Perforated Oil Filter	352	(2)
11.3 Major Engine Damage, Allegedly Due to Loss of Oil	354	(4)
11.4 Three-Car Road Accident	358	(7)
12 Criminal Cases	365	(14)
12.1 Counterfeit Coins	365	(3)
12.2 Shotgun Pellets	368	(2)
12.3 Metal Theft	370	(2)
12.4 Chain from Murder	372	(1)
12.5 Coin Box Busters	373	(2)
12.6 Remelting Beer Barrels	375	(4)
13 Intellectual Property Cases	379	(50)
13.1 Introduction	379	(2)
13.1.1 Patents	380	(1)
13.1.2 Case Studies	380	(1)
13.2 Wheeled Containers	381	(12)
13.2.1 The Lifting Lip	382	(3)
13.2.2 Plastic Bins	385	(1)
13.2.3 Growth in Use	386	(1)
13.2.4 The Steel Bin	387	(2)
13.2.5 The Trial (Schneider v Taylor)	389	(1)
13.2.6 Meaning of Terms	389	(1)
12.2.7 Alternative Interpretation	390	(2)
13.2.8 Standard Dimensions	392	(1)
13.2.9 Judgment	392	(1)
13.2.10 Afterword	393	(1)
13.3 Lawnmowers	393	(21)
13.3.1 History of Development	394	(1)
13.3.2 The Hover Principle	395	(1)
13.3.3 The Hovermower	395	(2)
13.3.4 Wheeled Rotary Mowers	397	(1)
13.3.5 Monocoque Mowers	397	(1)
13.3.6 The Rasenkatz Patent	398	(1)
13.3.7 Design Development Sequence	399	(6)
13.3.8 Pretrial Litigation	405	(1)
13.3.9 Discovery	405	(1)
13.3.10 The New Model	406	(1)
13.3.11 Main Trial (Black & Decker v. Flymo I)	406	(1)
13.3.12 Infringement	407	(1)
13.3.13 Validity	408	(1)
13.3.14 Wording of Claim 1	409	(2)
13.3.15 Judgment	411	(2)
13.3.16 Afterword	413	(1)
13.4 Electromechanical Devices	414	(11)
13.4.1 Residual Current Devices	414	(1)
13.4.2 Power Breaker v. Volex et al.	414	(1)
13.4.3 Patent-in-Suit	415	(3)
13.4.4 Modeling the Technical Effect	418	(2)
13.4.5 The Protector	420	(3)
13.4.6 The Trial (Patents County Court)	423	(2)
13.4.7 Afterword	425	(1)
13.5 Endword	425	(1)
References	426	(3)
Index	429