Fractography in Failure Analysis of Polymers

Fractography in Failure Analysis of Polymers
اسم المؤلف
Michael D. Hayes , Dale B. Edwards , Anand R. Shah
التاريخ
17 سبتمبر 2023
المشاهدات
306
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Fractography in Failure Analysis of Polymers
Michael D. Hayes
Engineering Systems Inc. (ESI), Atlanta, GA, USA
Dale B. Edwards
Engineering Systems Inc. (ESI), Aurora, IL, USA
Anand R. Shah
Engineering Systems Inc. (ESI), Aurora, IL, USA
Table of contents
Foreword
Preface
Acknowledgments

  1. Introduction
    1.1 Motivations
    1.2 What Is Fractography?
    1.3 Plastic Material Structure–Property Relationship
    1.4 Components of a Failure Investigation
    References
  2. Fractography as a Failure Analysis Tool
    2.1 Failure Analysis Fundamentals
    2.2 The Scientific Method
    2.3 Application of the Scientific Method
    2.4 The Role of Fractography in Failure Analysis
    References
  3. Instrumentation and Techniques
    3.1 Field or Site Instrumentation and Techniques
    3.2 Microscopic Examination of Fracture Surfaces in a Laboratory
    3.3 Consideration and Selection of Instruments in Failure Analysis
    3.4 Summary
    3.5 Regulatory Agencies
    References
  4. Fractography Basics
    4.1 Fracture Surface Features and Interpretation
    4.2 Brittle Versus Ductile Failures in Polymers
    4.3 Crack Path Analysis
    4.4 Fracture Features
    4.5 Application of Fractography to Failure Analysis
    References
  5. Long-Term Failure Mechanisms in Plastics
    5.1 Introduction
    5.2 Creep
    5.3 SCG/Creep Rupture
    5.4 Environmental Stress Cracking
    5.5 Aging, Degradation, and Surface Embrittlement
    5.6 Summary
    References
  6. Case Studies
    6.1 Introduction
    6.2 Organization of Case Studies
    6.3 Case Study 1: Composite Crossbow
    6.4 Case Study 2: Showerhead Bracket
    6.5 Case Study 3: Polycarbonate Axle Caps
    6.6 Case Study 4: Hot Water Heater Drain Valve
    6.7 Case Study 5: PEEK Coupling
    6.8 Case Study 6: Icemaker Valve Failure
    6.9 Case Study 7: Automotive Part, ABS
    6.10 Case Study 8: Seat Belt
    6.11 Case Study 9: Automotive Part, PC/ABS
    6.12 Case Study 10: CPVC Cover Plate
    6.13 Case Study 11: XLPE Storage Tank for Sulfuric Acid Storage
    6.14 Case Study 12: Oxidation Failure of HDPE Pipe in Water Service
    6.15 Case Study 13: Washing Machine Hose Failure
    6.16 Case Study 14: Polyacetal Crimp Fittings
    6.17 Case Study 15: PVC Water Main
    6.18 Case Study 16: SAN Battery Cases
    6.19 Case Study 17: Flame-Retarded Thermoformed PPE–PS
    6.20 Case Study 18: 8-in. PVC Pipe
    6.21 Case Study 19: Railcar Part, PPE+PS, 20% Glass Filled
    6.22 Case Study 20: 48-in. HDPE Pipe
    6.23 Case Study 21: HDPE Liner Pipe Used in a High-Pressure Steel Pipeline
    References
  7. Epilogue
    7.1 Failure Prevention
    Index
    Index
    Note: Page numbers followed by “f” and “t” refer to figures and tables, respectively.
    A
    Acetal, 1213
    Acetal crimp fitting, degradation of,
    106, 108f
    Acronyms, for commonly used plastic
    materials, 27t
    Acrylonitrile butadiene styrene
    (ABS), 104105, 141142,
    143f, 144, 144f
    fractured ABS boat steering wheel,
    106, 106f, 107f
    Aging, 103108
    American Association for the
    Advancement of Science, 17
    Amorphous thermoplastic, 3
    Archive, 14
    Argument from ignorance, 16
    ASTM D1600, 2728
    ASTM E1188, 36
    Automotive part, ABS (case study)
    anti-rattle trigger post, fracture
    surface of, 143f, 144f
    anti-rattle trigger post, overall
    appearance of, 142f
    background, 141
    conclusions, 144145
    failure analysis, 141144
    fracture, location of, 143f
    material flow and orange-peel-like
    surface finish of anti-rattle
    trigger post, 142f
    techniques, 141
    Automotive part, PC/ABS
    (case study), 148152
    background, 148
    conclusions, 151152
    failure analysis, 149151
    fracture origin location, 150f
    fracture progression in brittle
    manner, 151f
    fracture surface under stereozoom
    optical microscope, 150f
    new uncracked and cracked PC/
    ABS instrument panel, overall
    appearance of, 149f
    techniques, 148149
    B
    Background information, gathering,
    23, 2627
    Beach marks. See Rib markings
    Bifurcations of crack, 52
    Branching of crack. See Crack
    branching
    Brittle, 94
    Brittle fractures, 5557
    Brittle versus ductile failures, in
    polymers, 5360
    cautions, 5960
    plane stress and plane strain,
    5759
    C
    Carbonyl index (CI), 105106
    Case studies, 111
    automotive part
    ABS, 141145
    PC/ABS, 148152
    composite crossbow, 114120
    CPVC cover plate, 152156
    8-in. PVC pipe, 190195
    227Case studies (Continued)
    flame-retarded thermoformed
    PPE-PS, 185190
    48-in. HDPE pipe, 203211
    HDPE liner pipe used in a highpressure steel pipeline,
    211221
    hot water heater drain valve,
    128130
    icemaker valve failure, 134141
    oxidation failure of HDPE pipe in
    water service, 165168
    PEEK coupling, 130134
    polyacetal crimp fittings, 173177
    polycarbonate axle caps, 123127
    PVC water main, 177180
    railcar part, PPE 1 PS, 20% glass
    filled, 195203
    SAN battery cases, 180185
    seat belt, 145148
    showerhead bracket, 120123
    washing machine hose failure,
    168173
    XLPE storage tank for sulfuric acid
    storage, 156165
    Causes versus mechanisms, 67
    Chemical evident on fracture
    surface, 53
    Compound microscopes, 39
    Compounding additives, 44
    Conic markings, 88, 88f
    CPVC cover plate,
    case study, 152156
    background, 152
    conclusions, 155156
    cracks at second machined
    hole in, 153f
    failure analysis, 152155
    fluid emanating from crack in,
    154f, 155f
    fracture origin area near
    machined hole, 154f
    fracture surface from fractured
    CPVC cover plate, 153f
    fractures at machined hole, 152f
    sharp ledges on very smooth
    surface, 154f
    techniques, 152
    CPVC elbow fitting, 29
    CPVC ESC failure, 89, 90f
    CPVC pipe, 8384, 85f
    crack in, 102f
    depict fracture surfaces
    of, 8384, 85f
    evidence of microductility on
    fracture surface of, 102f
    mechanically driven
    crack in, 103f
    Crack arrest marks, 7071
    Crack branching, 52, 61, 62f
    Crack growth, 7, 5960, 61f, 77
    Crack opening displacement, 34
    Crack path analysis, 6162
    Crack propagation, 74, 94, 165166,
    190191
    Crazing in polymers, 57
    Creep, 9395
    brittle, 94
    deformation, 94
    glass transition temperature, 95
    response, 94
    rupture, 94
    failure, 4849, 8687
    Critical stress, 98100, 102103
    Crossbow, case study, 114120
    additional secondary cracks along
    fractured area, 116f
    background, 114115
    conclusions, 119120
    fractured crossbow, 115f
    fractured end of, 116f
    large voids and stress whitening,
    117f
    stress whitening and rubbed
    surface of, 119f
    surface damage near fracture
    origin area, 116f
    techniques/analysis, 115119
    228 INDEXvisibility of internal voids on
    fracture surface, 118f
    visibility of large voids in the
    interior of stock, 118f
    voids near fracture origin at the
    underside of crossbow body,
    118f
    wear marks on stock near fracture
    origin, 117f
    Cross-linked PE (PEX) pipe
    cracks branching in, 62f
    fracture origin at a void in, 65f
    undercut ledges
    on fracture surface near origin
    in, 90f
    in PEX tank fracture near
    origin, 90f
    D
    Damage development, 7
    Daubert v. Merrell Dow
    Pharmaceuticals, Inc., 19
    Deductive reasoning, 1416
    Defects versus imperfections, 912
    Degradation, 64, 7173, 103108
    Design defects, 89
    Design deficiencies, 1213
    Differential scanning calorimeter
    (DSC), 44
    Documentation, 26
    photo, 31f, 35f
    Ductile creep failures, 95
    Ductile failures, in polymers, 5360
    Ductile fracture origin, 68f
    Ductility, on fracture surface, 49
    Dye penetrants, 41, 42f
    E
    Electromagnetic lenses, 43
    Embrittlement, 103108
    Energy-dispersive X-ray spectroscopy
    (EDS), 171, 183, 192, 208
    Environmental SEM (E-SEM),
    4243
    Environmental stress crack resistance
    (ESCR) testing, 208, 212
    Environmental stress cracking (ESC),
    96103, 127, 140, 152153,
    155156, 181183,
    185190, 196198
    agent, 9697
    characteristics of, 96
    differentiating SCG/creep from,
    100103
    failures, 49, 67f
    Environmental variables affecting
    product performance, 225t
    Evidence, definition of, 14
    F
    Fabrication errors, 89
    Failure analysis fundamentals, 613
    causes versus mechanisms, 67
    defects versus imperfections, 912
    design deficiencies, 1213
    fractography’s role in, 2021
    material selection, 1213
    primary versus secondary causes, 8
    root causes, types of, 89
    Failure investigation, 23
    basic elements, 17
    components of, 34
    “Failure of will,” fallacy of, 15
    Failure prevention, 223226
    Fallacies/user error, 1516
    Fallacious logic, 1516
    Fast fracture area on fracture surface,
    5253
    Fatigue striations, 7887
    fatigue crack growth versus slow
    crack growth, 8387
    on fracture surface of PS
    toothbrush failure, 7881, 80f
    on fracture surface of SAN field
    fracture, 7881, 80f
    on HDPE pipe fracture surface,
    7881, 81f
    Field investigation, 2438
    INDEX 229Field investigation (Continued)
    field microscopy, 37
    information gathering, 2526
    photogrammetry and digitization,
    3738
    product specific information, visual
    inspection for, 2633
    visual and photographic
    techniques, 3337
    Finite element analysis (FEA), 140f,
    163, 171, 172f, 174175, 196,
    200, 202
    Flame-retarded thermoformed PPEPS, case study, 185190
    background, 185
    conclusions, 189190
    cracking at thermoformed bend in
    the bus seat material, 187f
    cracking of plastic seat material
    adjacent to attachment to
    frame, 186f
    cracks around attachment hole in
    seat material, 186f
    failure analysis, 186189
    SEM images of cracks, 187f
    smooth fracture origin at outer
    surface of the seat panel, 188f
    strain measurements, 188189,
    189f
    techniques, 185186
    Flaw, 10
    Foreign materials on fracture
    surface, 53
    Forking, 61
    Fourier transform infrared (FTIR)
    spectroscopy, 152, 155f
    Fractography, definition of, 2
    Fracture features, 6290
    conic or parabolic
    markings, 88, 88f
    fatigue striations, 7887
    fatigue crack growth versus slow
    crack growth, 8387
    fracture origin(s), 6365
    hackles, 7475
    mirror zone, 6670
    mist region, 70
    ratchet marks or
    ledges, 8990, 89f
    rib markings/beach marks, 7073
    river patterns or river markings,
    7577
    Wallner lines, 7778
    Fracture modes, 5152, 52f
    Fracture origin, 6466
    at geometric discontinuity in
    PMMA, 66f
    at an inclusion in PVC, 65f
    at a void in PEX tube, 65f
    Fracture surface, 4853
    acrylic, 74, 76f
    bifurcations of crack, 52
    crack branching, 52
    ductility, 49
    failure characteristics, 4849
    fast fracture area on, 5253
    foreign materials or
    chemicals on, 53
    fracture direction for mating
    parts, 5152
    location and nature of fracture
    origin, 49
    microscopic examination of,
    3843
    optical microscopy, 3941
    scanning electron microscopy
    (SEM), 4243
    river patterns/hackles on, 77, 77f
    roughness, 50
    slow crack growth (SCG) region
    on, 5253
    smoothness, 50
    straight/curved crack, 52
    stress whitening on, 50
    striations/lines on, 51
    T-junctions, 52
    undercut ledges on, 82, 90f
    various features of, 64f
    230 INDEXFracture type, identification of, 21
    Frye test, 19
    G
    Gel permeation chromatography
    (GPC), 147148, 147t
    Glass transition temperature, 95
    H
    Hackles, 7475, 75f
    HDPE liner pipe used in a highpressure steel pipeline, case
    study, 211221
    background, 211212
    conclusions, 220221
    failed liner pipes
    long fracture surfaces in, 213f
    typical outer surface gouges and
    scratches on, 212f
    failure analysis, 212220
    mechanical testing, 212
    multiple fracture origins, 150151,
    213215, 214f
    HDPE pipe, 49
    48-in. HDPE pipe (case study),
    203211
    background, 203204
    conclusions, 211
    cracks on inner surface of pipe
    sample, 205f
    cracks in the pipe, exposing,
    206f
    failure analysis, 209211
    fracture surfaces of different
    cracks, 206f, 207f
    material testing, 208209
    pipe section with approximate
    location of through-wall
    cracks, 204f
    section of HDPE pipe received
    for analysis, 203f
    techniques, 204209
    wall thickness measurements,
    204f, 205f
    crazing ahead of fatigue crack in,
    70, 71f, 72f
    degradation of, 107108
    failure in, 74f
    mud cracking of inner surface
    of, 108f
    point load failure in, 73f
    rib markings on, 73f
    in water service, oxidation failure
    of (case study), 165168
    background, 165
    conclusions, 168
    crack in pipe after sectioning the
    pipe longitudinally, 166f
    embrittled inner surface, SCG,
    and mud cracking on inner
    surface of the pipe, 167f
    failure analysis, 166168
    five mil depth of degraded
    material at inner surface, 167f
    HDPE pipe sample with
    crack, 166f
    techniques, 165166
    HDPE tensile test specimen, 5455
    before and after testing, 55f
    notched and cooled in liquid
    nitrogen, 56f
    tested with razor notch, 56f
    High-density polyethylene. See HDPE
    Hooke’s law, 5758
    Hot water heater drain valve, case
    study, 128130, 128f
    background, 128
    conclusions, 130
    techniques and
    analysis, 128130, 129f
    Human roots, causes of failure, 9
    I
    Icemaker valve failure, case study,
    134141
    background, 134135
    conclusions, 141
    failure analysis, 138141, 139f
    INDEX 231Icemaker valve failure, case study
    (Continued)
    Faro laser scan deviation plots
    for subject plate, 138f
    for typical exemplar plate, 138f
    inspection, 135137
    crack on outlet stem portion of
    valve body, 136f
    lab examination, 135137
    laser scan of guide plates, 137
    separated valve body showing
    fracture surfaces, 136f
    subject icemaker, 134f, 135f
    Imperfections, 912
    Inadmissible evidence, 15
    Inductive reasoning, 1416
    Information gathering, 2526
    environmental factors, 26
    Injection molding, 29, 30f
    Instrumentation/techniques
    consideration and selection of,
    4345, 45t
    field/site investigation, 2438
    field microscopy, 37
    information gathering, 2526
    photogrammetry and digitization,
    3738
    product specific information,
    visual inspection for, 2633
    visual and photographic
    techniques, 3337
    microscopic examination of
    fracture surfaces, 3843
    environmental SEM
    (E-SEM), 4243
    optical microscopy, 3941
    scanning electron microscopy
    (SEM), 4243
    regulatory agencies, 4647
    Irrelevant evidence, 15
    L
    Laser scanning, 25, 38
    Latent roots, 9
    Linear elastic fracture mechanics
    (LEFM), 179, 194
    Linear-low-density polyethylene
    (PELLD), 28
    Liquid crystal polymer (LCP), 82
    fatigue failure in, 84f
    fracture origin at the edge of, 85f
    Litigation standard, 1820
    Frye test, 19
    physical evidence, 18
    U.S. Federal Rules of Evidence
    702 (FRE), 1920
    Logic, definition of, 14
    Logic fallacies, 1516
    Long-term failure mechanisms, in
    plastics
    aging, 103108
    creep, 9395
    degradation, 103108
    environmental stress cracking
    (ESC), 96103
    differentiating SCG/creep from,
    100103
    SCG/creep structure, 9596
    surface embrittlement, 103108
    Low-density polyethylene (LDPE)
    resin, 145, 146f, 147148,
    147f
    M
    Manufacturer, identifying, 28
    Manufacturing date, documenting, 32
    Manufacturing defects, 89
    Material defects, 89
    Material properties, 4445, 45t
    Material selection, 1213, 224
    Microcracking, 35, 107f
    Microscopic examination of fracture
    surfaces, 3843
    optical microscopy, 3941
    scanning electron microscopy
    (SEM), 4243
    environmental SEM (E-SEM),
    4243
    232 INDEXMicrovoids in plastics, 5960
    Mirror zone, 6670, 69f
    Mist region, 70, 71f
    Mode of failure, 67
    Mud cracking, 106, 108f
    N
    National Fire Protection Association
    (NFPA), 1617
    Noryl resin, 185190, 195196,
    202203
    GFN2 701 material, 200202
    stress rupture curve for, 202f
    mechanical properties of, 188t
    Nylon axial fatigue test, 82, 83f
    O
    Optical microscopy, 23, 3941
    categories of, 39
    limitations of, 4041
    Organic synthetic polymers, 23
    Oxidation induction time (OIT),
    159160, 165166, 168
    P
    Parabolic markings, 88, 88f
    Part failure, 12
    PE 3408 tensile specimen
    brittle fracture of, 5455, 56f
    ductile failure of, 5455, 55f, 56f
    PEL model, 14
    PELA model, 14
    Photogrammetry and
    digitization, 25, 3738
    laser scanning, 38
    PhotoModeler Scanner software,
    3738
    Physical evidence, 16, 18
    Physical roots, 9
    Plane strain, 5759, 9596
    Plane stress, 5759
    Polyacetal crimp fittings, case study,
    173177
    background, 173
    conclusions, 176177
    crimp fitting assembly, schematic
    of, 175f
    failure analysis, 173176
    field failure, 174f
    techniques, 173
    Polycarbonate (PC) axle caps, case
    study, 123127
    appearance of fracture surface
    showing crack initiation, 125f
    background, 123
    conclusions, 127
    failed axle cap with complete
    circumferential fracture, 124f
    failure analysis, 125127, 127f
    molding flaws, 125f, 126f
    observations, 123125
    partial crack under flange near
    gate, 124f
    two truck wheel axle caps, 124f
    Polycarbonate part, depict fracture
    surfaces of, 8384, 86f
    Polyetherether ketone (PEEK)
    coupling, case study,
    130134, 131f
    background, 130
    conclusions, 134
    failure analysis, 133134
    multiple fracture origins and
    fatigue striations, 133f
    multiple initiation sites and fatigue
    striations, 132f
    observations, 130132
    semi-elliptical fatigue fracture
    origins, 131f
    small cutout fragment, 131f
    fracture surface on, 131f
    surface and microvoids/
    microcracks, 133f
    thin section of cutout fragment,
    mating fracture in, 132f
    Polyethylene (PE), 9798
    high-magnification fracture
    surface in, 60f
    INDEX 233Polyethylene (PE) (Continued)
    low-magnification view of
    SCG in, 60f
    Polymer classification, 23
    Polymer material variables, 224t
    Polymeric materials, basic fracture
    features in, 63t
    Polymethyl methacrylate (PMMA)
    fracture origin at geometric
    discontinuity in, 66f
    mirror zone at the origin area of
    brittle fracture in, 68f
    multiple crazes in, 54
    Polyphenylene etherpolystyrene
    (PPE-PS) material, 50
    ESC failure in, 51f
    Polystyrene (PS), 4849, 8182, 82f
    Polyvinyl chloride
    (PVC), 155156, 177180,
    177f, 190195
    8-in. PVC pipe, case study,
    190195
    background, 190
    conclusions, 194195
    crack initiation area, 193f
    critical pressure versus crack
    length, 195f
    failed PVC pipe, 191f
    failure analysis, 193194
    fractographic observations prior
    to destructive examination,
    191f
    fracture initiation region, 192f
    fracture surface,
    stereomicroscopy of, 192f
    techniques, 190192
    fracture origin at an
    inclusion in, 65f
    fracture surface, parabolic
    markings visible on, 88, 88f
    PVC water main, case study,
    177180
    background, 177
    conclusions, 180
    fracture origin area in the bell
    end of PVC pipe, 177f
    fracture origin showing SCG area
    and fast fracture area, 178f
    techniques and analysis,
    177180
    Presuppositions, 1415
    Processing variables, 224225, 225t
    Product performance, environmental
    variables affecting, 225t
    Product specific information, visual
    inspection for, 2633
    Punctuation marks, 2728
    R
    Railcar part, PPE 1 PS, 20% glass
    filled (case study), 195203
    background, 195196
    conclusions, 202203
    cracking, 197f, 198f
    evidence of fibers running
    longitudinal to the direction of
    fracture, 200f
    failure analysis, 196202
    finite element analysis, 200201
    stress relaxation testing, 202
    stress rupture testing, 201202
    thermogravimetric analysis
    (TGA), 198200
    fracture surface, examining, 199f
    techniques, 196
    vent assembly, 197f
    Ratchet marks/ledges, 8990, 89f
    Red herring, 1012, 15
    Retardation, 184
    Rib markings, 7073, 72f, 73f, 74f
    River markings, 7577
    River patterns, 7577
    Root cause, 23
    definition of, 8
    failure analysis, 8
    types of, 89
    Rotational molding, 3233
    Rubbers, 23
    234 INDEXS
    Safety concerns, checking, 25
    Scanned electron beam, 43
    Scanning electron microscopy (SEM),
    23, 4243, 113
    environmental SEM (E-SEM),
    4243
    Scientific method, 1316
    applications of, 1620
    litigation standard, 1820
    multidisciplinary approach,
    1718
    deductive versus inductive
    reasoning, 1416
    Seat Belt, case study, 145148
    background, 145
    conclusions, 148
    cracked LDPE seat belt
    scabbard, 146f
    failure analysis, 145147
    LDPE seat belt scabbard, fracture
    surface of, 147f
    loading on seat belt scabbard,
    single point source of, 146f
    techniques, 145
    Semicrystalline materials, 6667
    Semicrystalline polymers, 3,
    224225
    Service life anomalies, 89
    Shear yielding, 5657
    Showerhead bracket, case study,
    120123
    background, 120
    conclusions, 123
    crack initiation at injection
    gate, 122f
    cracking at gate location, 121f
    failure analysis, 121123
    fractured bracket, 121f
    hand-held shower product, overall
    view of, 120f
    higher magnification of crack at
    gate, 122f
    observations, 120121
    Simple microscopes, 39
    Site investigation. See Field
    investigation
    Slow crack growth (SCG), 48,
    5253, 5960
    continuous SCG in HDPE samples,
    8485, 86f
    discontinuous SCG in HDPE
    samples, 8485, 87f
    versus fatigue crack growth,
    8387
    low-magnification view of, in
    polyethylene, 60f
    SCG/creep rupture, 9596
    versus environmental stress
    cracking, 100103
    Solid-state structure, development
    of, 224225
    Stereomicroscopes, 39
    Strain optical coefficient, 184
    Straw-man argument, 16
    Stress crack agents, 100t, 101102
    Stress cracking failures in
    polyethylene, 9798
    Stress intensity factor, 6970,
    179180, 194
    Stress state, 58
    ahead of cracked or notched
    material, 58f
    in notched material, 59f
    Stress whitening on fracture surface,
    50
    Striations on fracture surface, 51
    Structureproperty
    relationship, 23, 44
    Styrene acrylonitrile (SAN) battery
    cases, case study, 180185
    background, 180
    conclusions, 185
    example of cracks, 181f
    failure analysis, 183184
    material found on fracture
    surface, 182f
    observations, 180182
    INDEX 235Styrene acrylonitrile (SAN) battery
    cases, case study (Continued)
    photoelastic birefringence patterns
    around gates, 184f
    typical fracture surface, 182f
    Styrene acrylonitrile (SAN) field
    fracture, 7881, 80f
    Surface embrittlement of polymers, 103
    T
    Tensile test, 54, 54f
    HDPE, 55f, 56f
    Thermoplastic, 23
    Thermosets, 23
    T-junctions, 52, 6162
    Twist hackle, 7475, 76f, 77
    U
    Undercut ledges on fracture surface,
    82, 90f
    Uniaxial and biaxial stress states,
    5657
    U.S. Federal Rules of Evidence 702
    (FRE), 1920
    “Unobtainable perfection,” 15
    User errors, 89, 15
    UV degradation, 104
    V
    Variabilities in materials, 10
    Viscoelasticity, 9394
    Visual and photographic techniques,
    3337, 36t
    ASTM E1188, 36
    digital camera and accessories,
    3334, 34t
    hand-held instruments, 33
    microcracks identification, 35
    Visual inspection for product specific
    information, 2633
    manufacturing date, documenting, 32
    rotational molding, 3233
    V-shaped dual gooseneck flexible
    light adapter, 39
    W
    Wallner lines, 7778, 78f, 79f
    Washing machine hose failure, case
    study, 168173
    background, 168
    conclusions, 173
    crack pattern on inner surface, 169f
    exemplar part, cross section of,
    172f
    failed washing machine hose, 169f
    failure analysis, 171172
    FEA of tube in bending that is
    constrained on right end, 172f
    fracture surface, 169f
    fracture surface, 170f
    observations, 168171
    tool marks, 170f
    Wehnelt cylinder, 42
    X
    XLPE storage tank for sulfuric
    acid storage, case study,
    156165
    background, 156158
    bottom surface of the tank, 157f
    changes in elevation, visualizing,
    160, 161f
    conclusions, 163165
    crack in bottom panel, 157f
    ductility on fracture surface, 159f
    failure analysis, 159163
    hackles in final fracture region near
    outer surface, 161f
    microcracking, 159f
    removed section containing crack
    (s), 157f
    step at tailing edge of a void in
    UHMWPE, 162f
    step in PC, 161f
    step in PE, 162f
    steps at an inclusion in PE
    pipe, 162f
    subject tank, 156f
    techniques, 158

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