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 |  موضوع: كتاب Fractography in Failure Analysis of Polymers الأحد 17 سبتمبر 2023, 1:57 am | |
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أحضرت لكم كتاب
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
و المحتوى كما يلي :
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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