ASTM E1823-96(2002)

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Designation: E 1823 – 96 (Reapproved 2002)
Standard Terminology
Relating to Fatigue and Fracture Testing
This standard is issued under the fixed designation E1823; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope E740 Practice for Fracture Testing with Surface-Crack
Tension Specimens
1.1 This terminology contains definitions, definitions of
E812 Test Method for Crack Strength of Slow-Bend Pre-
terms specific to certain standards, symbols, and abbreviations
cracked Charpy Specimens of High-Strength Metallic
approved for use in standards on fatigue and fracture testing.
Materials
The definitions are preceded by two lists. The first is an
E813 Test Method for J , a Measure of Fracture Tough-
alphabetical listing of symbols used. (Greek symbols are listed Ic
ness
in accordance with their spelling in English.) The second is an
E992 Practice for Determination of Fracture Toughness of
alphabetical listing of relevant abbreviations.
Steels Using Equivalent Energy Methodology
1.2 This terminology includes Annex A1 on Units and
E1049 Practices for Cycle Counting in Fatigue Analysis
AnnexA2 on Designation Codes for Specimen Configuration,
E1152 Test Method for Determining J-R Curves
Applied Loading, and Crack or Notch Orientation.
E1221 Test Method for Determining Plane-Strain Crack-
2. Referenced Documents
Arrest Fracture Toughness, K , of Ferritic Steels
Ia
E1290 Test Method for Crack-Tip Opening Displacement
2.1 ASTM Standards:
(CTOD) Fracture Toughness Measurement
E6 Terminology Relating to Methods of Mechanical Test-
E 1304 Test Method for Plane-Strain (Chevron-Notch)
ing
Fracture Toughness of Metallic Materials
E338 Test Method for Sharp-Notch Tension Testing of
E1457 Test Method for Measurement of Creep Crack
High-Strength Sheet Materials
Growth Rates in Metals
E399 Test Method for Plane-Strain Fracture Toughness of
E1681 Test Method for Determining a Threshold Stress
Metallic Materials
Intensity Factor for Environment-Assisted Cracking of
E436 Test Method for Drop-Weight Tear Tests of Ferritic
Metallic Materials Under Constant Load
Steels
E1737 TestMethodforJ-IntegralCharacterizationofFrac-
E466 Practice for Conducting Force-Controlled Constant
ture Toughness
Amplitude Axial Fatigue Tests of Metallic Materials
E1820 Test Method for Measurement of Fracture Tough-
E467 Practice for Verification of Constant Amplitude Dy-
ness
namic Forces in an Axial Load Fatigue Testing System
G15 Terminology Relating to Corrosion and Corrosion
E468 Practice for Presentation of Constant Amplitude Fa-
Testing
tigue Test Results for Metallic Materials
E561 Practice for R-Curve Determination
3. Terminology
E602 Test Method for Sharp-Notch Tension Testing with
3.1 AlphabeticalListingofPrincipalSymbolsUsedinThis
Cylindrical Specimens
Terminology:
E604 Test Method for Dynamic Tear Testing of Metallic
Materials
Symbol Term
E606 Practice for Strain-Controlled Fatigue Testing
a crack depth, crack length, crack size, estimated crack
E647 Test Method for Measurement of Fatigue Crack size
a effective crack size
e
Growth Rates
a notch length
n
E739 Practice for Statistical Analysis of Linear or Linear-
a original crack size
o
ized Stress-Life (S-N) and Strain-Life (e-N) Fatigue Data
1 3
ThisterminologyisunderthejurisdictionofASTMCommitteeE08onFatigue Discontinued.ReplacedbyE1737.See1996AnnualBookofASTMStandards,
and Fracture and is the direct responsibility of Subcommittee E08.02 on Standards Vol 03.01.
and Terminology. Discontinued. See 1996 Annual Book of ASTM Standards, Vol 03.01.
Current edition approved Oct. 10, 2002. Published April 2003. Originally Discontinued.ReplacedbyE1820.See1997AnnualBookofASTMStandards,
approved in 1996. Last previous edition approved in 1996 as E1823–96. Vol 03.01.
2 6
Annual Book of ASTM Standards, Vol 03.01. Annual Book of ASTM Standards, Vol 03.02.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
E 1823 – 96 (2002)
Symbol Term Symbol Term
a physical crack size T specimen temperature
p
a/W normalized crack size t transition time
T
A load ratio (P /P ) t total cycle period
a m t
A net-section area t ,t , t shear stresses (refer to Fig. 1)
N xy yz zx
b remaining ligament u displacement in x direction
b original uncracked ligament v displacement in y direction
o
B specimen thickness 2v crack-mouth opening displacement
m
B effective thickness V load-line displacement due to creep
e c
B net thickness w displacement in z direction
N
2c surface-crack length W specimen width
C normalized K-gradient Y* stress-intensity factor coefficient
D cycle ratio (n/N ) Y* minimum stress-intensity factor coefficient
f m
C*(t) C*(t) − Integral
3.2 Alphabetical Listing of Abbreviations Used:
da/dN fatigue-crack-growth rate
d crack-tip opening displacement (CTOD)
CMOD crack-mouth opening displacement
dd speciment gage length
COD see CTOD
Da crack extension, estimated crack extension
CTOD crack-tip opening displacement
DK stress-intensity-factor range
DT dynamic tear
DK fatigue-crack-growth threshold
th
DWTT drop-weight tear test
DP load range
EAC environment-assisted cracking
e strain amplitude
a
K-EE equivalent-energy fracture toughness
e inelastic strain
in NTS notch tensile strength
e mean load
m
PS part-through surface
G crack-extension force
SCC stress corrosion cracking
G crack-extension resistance
R
SZW stretch zone width
H* specimen center of pin hole distance
G the path of the J-integral
3.3 Definitions—Each definition is followed by the desig-
JJ-integral
nation(s) of the standard(s) of origin. The listing of definitions
J plane-strain fracture toughness
Ic
is alphabetical.
J crack-extension resistance
R
k fatigue notch factor
f
alternating load—See loading amplitude.
k theoretical stress concentration factor (sometimes ab-
t
breviated stress concentration factor)
block—in fatigue loading, a specified number of constant
K, K , K , K , stress-intensity factor (see mode)
1 2 3
amplitude loading cycles applied consecutively, or a spec-
K , K , K
I II III
trum loading sequence of finite length that is repeated
K crack-arrest fracture toughness
a
K plane-stress fracture toughness
c identically. E 1823
K stress intensity factor threshold for environment-
EAC
blunting line—in fracture testing, a line that approximates
assisted cracking
apparent crack advance due to crack-tip blunting in the
K plane-strain crack-arrest fracture toughness
Ia
K stress intensity factor threshold for plane strain
IEAC absence of slow stable crack tearing. The line is defined
environment-assisted cracking
based on the assumption that the crack advance is equal to
K plane-strain fracture toughness
Ic
onehalfofthecrack-tipopeningdisplacement.Thisestimate
K , K , K plane-strain (chevron-notch) fracture toughness
IvM Iv Ivj
K maximum stress-intensity factor
max
of pseudo-crack advance, Da , is based on the effective
B
K minimum stress-intensity factor
min
yield strength of the material tested. E 813
K stress-intensity factor at crack initiation
o
K crack-extension resistance
R
Da 5 J/2 s (1)
B Y
n cycles endured 3 −1
circulation rate [L T ]—in fatigue testing, the volume rate
N fatigue life
f
of change of the environment chamber volume. E 1823
P load
P load amplitude
a
clipping—in fatigue spectrum loading, the process of decreas-
P mean load
m
ingorincreasingthemagnitudeofallloads(strains)thatare,
P precrack load
M
P maximum load respectively, above or below a specified level, referred to as
max
P minimum load
min
clipping level; the loads (strains) are decreased or increased
q fatigue notch sensitivity
to the clipping level (see Fig. 2). E 1823
r effective unloading slope ratio
−1
compliance (LF ],n—theratioofdisplacementincrementto
r critical slope ratio
c
r plastic-zone adjustment
y
load increment. E 1820
R load ratio (P /P )
min max
confidence interval—an interval estimate of a population
s sample standard deviation
parameter computed so that the statement 88the population
s sample variance
S specimen span
parameter included in this interval” will be true, on the
S load amplitude
a
average, in a stated proportion of the times such computa-
S fatigue limit
f
S mean load tions are made based on different samples from the popula-
m
S fatigue strength at N cycles
N
tion. E 1823
s crack strength
c
confidence level (or coefficient)—the stated proportion of the
s nominal (net-section) stress
N
s residual strength times the confidence interval is expected to include the
r
s sharp-notch strength
s
population parameter. E 1823
s tensile strength
TS
confidence limits—the two statistics that define a confidence
s , s , s normal stresses (refer to )
x y z
s effective yield strength interval. E 1823
Y
s yield strength
YS
constant amplitude loading— in fatigue loading, a loading
E 1823 – 96 (2002)
NOTE—See definition of mode.
FIG. 1 Customary Coordinate System and Stress on a Small Volume Element Located on the x Axis Just Ahead of the Crack Front
FIG. 2 Clipping of Fatigue Spectrum Loading
(straining) in which all of the peak loads (strains) are equal gular coordinates) of a family of curves each of which is for
and all of the valley loads (strains) are equal. E 1049 a single fatigue life, N, relating stress amplitude, S , to mean
a
constant life diagram— in fatigue, a plot (usually on rectan- stress, S , or maximum stress, S , or both, to minimum
m max
E 1823 – 96 (2002)
is measured on the specimen surface at the midpoint of the crack
stress, S . The constant life fatigue diagram is usually
min
length. E 740
derived from a family of S-N curves each of which repre-
sents a different stress ratio (A or R) for a 50% probability
crack-plane orientation—an identification of the plane and
of survival. E 1823
direction of a fracture in relation to product configuration.
corrosion fatigue—the process by which fracture occurs
This identification is designated by a hyphenated code with
prematurely under conditions of simultaneous corrosion and
the first letter(s) representing the direction normal to the
repeatedcyclicloadingatlowerstresslevelsorfewercycles
crackplaneandthesecondletter(s)designatingtheexpected
than would be required in the absence of the corrosive
direction of crack propagation.
environment. G15
DISCUSSION—See also Annex A2, (A2.4 on crack or notch orienta-
counting method—in fatigue spectrum loading, a method of
tion). E 399
counting the occurrences and defining the magnitude of
various loading parameters from a load-time history; (some
crack size, a [L]—a lineal measure of a principal planar
of the counting methods are: level crossing count, peak
dimensionofacrack.Thismeasureiscommonlyusedinthe
count, mean crossing peak count, range count, range-pair
calculation of quantities descriptive of the stress and dis-
count, rain-flow count, racetrack count). E 1049
placement fields and is often also termed crack length or
crack displacement [L]—the load-induced separation vector
depth.
between two points (on the facing surfaces of a crack) that
DISCUSSION—In practice, the value of a is obtained from procedures
were initially coincident.
for measurement of physical crack size, a , original crack size, a , and
p o
DISCUSSION—In Practice E561, displacement is the distance that a
effectivecracksize,a ,asappropriatetothesituationbeingconsidered.
e
chosen measurement point on the specimen displaces normal to the
E 647
crack plane. Measurement points on the C(W) and C(T) specimen
−2
crack strength, s [FL ]—the maximum value of the nomi-
configurations are identified as locations V0, V1, and V2. E 561 c
nal stress that a cracked structure is capable of sustaining.
crack extension, Da [L]—an increase in crack size.
DISCUSSION—1 Crack strength is calculated on the basis of the
DISCUSSION—For example, in Practice E561, Da or Da is the
p e maximum load and the original minimum cross-sectional area (net
difference between the crack size, either a (physical crack size) or a
p e cross section or ligament). Thus, it takes into account the original size
of the crack but ignores any crack extension that may occur during the
(effective crack size), and a (original crack size). E 561
o
test.
−1 −2
crack-extension force, G [FL or FLL ]—the elastic en-
DISCUSSION—2 Crack strength is analogous to the ultimate tensile
ergyperunitofnewseparationareathatismadeavailableat strength, as it is based on the ratio of the maximum load to the
the front of an ideal crack in an elastic solid during a virtual
minimum cross-sectional area at the start of the test. E 338, E 602
increment of forward crack extension.
crack-tip opening displacement (CTOD), d, [L]—the crack
DISCUSSION—This force concept implies an analytical model for
displacement resulting from the total deformation (elastic
which the stress-strain relations are regarded as elastic. The preceding
plus plastic) at variously defined locations near the original
definition of G applies to either static cracks or running cracks. From
(prior to load application) crack tip.
past usage, G is commonly associated with linear-elastic methods of
analysis, although the J (see J-integral) also may be used for such
DISCUSSION—In common practice, d is estimated for Mode 1 by
inference from observations of crack displacement nearby or away, or
analyses. E 1823
both, from the crack tip. E 1290
−3/2 −1
crack-extension resistance, K [FL ], G [FL ]or J
R R R
−1
crack-tip plane strain—a stress-strain field (near the crack
[FL ]—a measure of the resistance of a material to crack
tip)thatapproachesplanestraintothedegreerequiredbyan
extensionexpressedintermsofthestress-intensityfactor,K;
empirical criterion.
crack-extension force, G; or values of J derived using the
J-integral concept.
DISCUSSION—For example, in Mode 1, the criterion for crack-tip
plane strain given by Test Method E399 requires that plate thickness,
DISCUSSION—See definition of R-curve. E 561
B, must be equal to or greater than 2.5 (K/s ) . E 399
YS
crack length, a [L]—See crack size and surface crack length.
crack-tip plane stress—astress-strainfield(nearthecracktip)
Also see crack length in the Description of Terms. For
that is not in plane strain.
example, in the C(T) specimen, a is measured from the line
DISCUSSION—In such situations, a significant degree of plane strain
connecting the bearing points of load application; in the
may be present. E 1823
M(T) specimen, a is measured from the perpendicular
bisector
...