ASTM E1823-96e1
(Terminology)Standard Terminology Relating to Fatigue and Fracture Testing
Standard Terminology Relating to Fatigue and Fracture Testing
SCOPE
1.1 This terminology contains definitions, definitions of terms specific to certain standards, symbols, and abbreviations approved for use in standards on fatigue and fracture testing. the definitions are preceded by two lists. The first is an alphabetical listing of the symbols used. (Greek symbols are listed in accordance with their spelling in English.) The second is an alphabetical listing of relevant abbreviations.
1.2 This terminology includes Annex A1 on Units and Annex A2 on Designation Codes for Specimen Configuration, applied Loading, and Crack or Notch Orientation.
General Information
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Standards Content (Sample)
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e1
Designation: E 1823 – 96
Standard Terminology
Relating to Fatigue and Fracture Testing
This standard is issued under the fixed designation E 1823; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
e NOTE—This standard was updated editorially in February 1997.
1. Scope ized Stress-Life (S-N) and Strain-Life (e-N) Fatigue Data
E 740 Practice for Fracture Testing with Surface-Crack
1.1 This terminology contains definitions, definitions of
Tension Specimens
terms specific to certain standards, symbols, and abbreviations
E 812 Test Method for Crack Strength of Slow-Bend Pre-
approved for use in standards on fatigue and fracture testing.
cracked Charpy Specimens of High-Strength Metallic
The definitions are preceded by two lists. The first is an
Materials
alphabetical listing of symbols used. (Greek symbols are listed
E 813 Test Method for J , A Measure of Fracture Tough-
Ic
in accordance with their spelling in English.) The second is an
ness
alphabetical listing of relevant abbreviations.
E 992 Practice for Determination of Fracture Toughness of
1.2 This terminology includes Annex A1 on Units and
Steels Using Equivalent Energy Methodology
Annex A2 on Designation Codes for Specimen Configuration,
E 1049 Practices for Cycle Counting in Fatigue Analysis
Applied Loading, and Crack or Notch Orientation.
E 1152 Test Method for Determining J-R Curves
2. Referenced Documents
E 1221 Test Method for Determining Plane-Strain Crack-
Arrest Fracture Toughness, K , of Ferritic Steels
2.1 ASTM Standards: Ia
E 1290 Test Method for Crack-Tip Opening Displacement
E 6 Terminology Relating to Methods of Mechanical Test-
(CTOD) Fracture Toughness Measurement
ing
E 1304 Test Method for Plane-Strain (Chevron-Notch)
E 338 Test Method for Sharp-Notch Tension Testing of
Fracture Toughness of Metallic Materials
High-Strength Sheet Materials
E 1457 Test Method for Measurement of Creep Crack
E 399 Test Method for Plane-Strain Fracture Toughness of
Growth Rates in Metals
Metallic Materials
E 1681 Test Method for Determining a Threshold Stress
E 436 Test Method for Drop-Weight Tear Tests of Ferritic
Intensity Factor for Environment-Assisted Cracking of
Steels
Metallic Materials Under Constant Load
E 466 Practice for Conducting Force-Controlled Constant
E 1737 Test Method for J-Integral Characterization of Frac-
Amplitude Axial Fatigue Tests of Metallic Materials
ture Toughness
E 467 Practice for Verification of Constant Amplitude Dy-
E 1820 Test Method for Measurement of Fracture Tough-
namic Loads on Displacements in an Axial Load Fatigue
ness
Testing System
G 15 Terminology Relating to Corrosion and Corrosion
E 468 Practice for Presentation of Constant Amplitude Fa-
Testing
tigue Test Results for Metallic Materials
E 561 Practice for R-Curve Determination
3. Terminology
E 602 Test Method for Sharp-Notch Tension Testing with
2 3.1 Symbols: Alphabetical Listing of Principal Symbols
Cylindrical Specimens
Used in This Terminology:
E 604 Test Method for Dynamic Tear Testing of Metallic
Materials
Symbol Term
E 606 Practice for Strain-Controlled Fatigue Testing
a crack depth, crack length, crack size, estimated crack
E 647 Test Method for Measurement of Fatigue Crack
size
a effective crack size
e
Growth Rates
a notch length
n
E 739 Practice for Statistical Analysis of Linear or Linear-
a original crack size
o
a physical crack size
p
a/W normalized crack size
A load ratio (P /P )
This terminology is under the jurisdiction of ASTM Committee E-8 on Fatigue a m
and Fracture and is the direct responsibility of Subcommittee E08.02 on Standards
and Terminology.
Current edition approved June 10, 1996. Published August 1996.
2 3
Annual Book of ASTM Standards, Vol 03.01. Annual Book of ASTM Standards, Vol 03.02.
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NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
E 1823
Symbol Term Symbol Term
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
K crack-arrest fracture toughness trum loading sequence of finite length that is repeated
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
K plane-strain crack-arrest fracture toughness apparent crack advance due to crack-tip blunting in the
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
K , K , K plane-strain (chevron-notch) fracture toughness one half of the crack-tip opening displacement. This estimate
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
P load of change of the environment chamber volume. E 1823
P load amplitude
a
clipping—in fatigue spectrum loading, the process of decreas-
P mean load
m
ing or increasing the magnitude of all loads (strains) that are,
P precrack load
M
P maximum load
max respectively, above or below a specified level, referred to as
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
r critical slope ratio
compliance (LF ], n— the ratio of displacement increment to
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
s sample variance
parameter computed so that the statement 88the population
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
m tions are made based on different samples from the popula-
S fatigue strength at N cycles
N
tion. E 1823
s crack strength
c
s nominal (net-section) stress confidence level (or coefficient)—the stated proportion of the
N
s residual strength
r
times the confidence interval is expected to include the
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
Y
interval. E 1823
s yield strength
YS
constant amplitude loading— in fatigue loading, a loading
T specimen temperature
t transition time (straining) in which all of the peak loads (strains) are equal
T
t total cycle period
t
and all of the valley loads (strains) are equal. E 1049
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
E 1823
NOTE 1—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
constant life diagram— in fatigue, a plot (usually on rectan- derived from a family of S-N curves each of which repre-
gular coordinates) of a family of curves each of which is for sents a different stress ratio (A or R) for a 50 % probability
a single fatigue life, N, relating stress amplitude, S , to mean of survival. E 1823
a
stress, S , or maximum stress, S , or both, to minimum corrosion fatigue—the process by which fracture occurs
m max
stress, S . The constant life fatigue diagram is usually prematurely under conditions of simultaneous corrosion and
min
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
E 1823
repeated cyclic loading at lower stress levels or fewer cycles crack plane and the second letter(s) designating the expected
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 dimension of a crack. This measure is commonly used in the
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
effective crack size, a , as appropriate to the situation being considered.
e
DISCUSSION—In Practice E 561, displacement is the distance that a
E 647
chosen measurement point on the specimen displaces normal to the
crack plane. Measurement points on the C(W) and C(T) specimen
cumulative frequency spectrum—See exceedances spectrum.
configurations are identified as locations V0, V1, and V2. E 561
cumulative occurrences spectrum—See exceedances spec-
crack extension, Da [L]—an increase in crack size.
trum.
−2
crack strength, s [FL ]—the maximum value of the nomi-
c
DISCUSSION—For example, in Practice E 561, Da or Da is the
p e
nal stress that a cracked structure is capable of sustaining.
difference between the crack size, either a (physical crack size) or a
p e
(effective crack size), and a (original crack size). E 561
o DISCUSSION—1 Crack strength is calculated on the basis of the
maximum load and the original minimum cross-sectional area (net
−1 −2
crack-extension force, G [FL or FLL ]—the elastic en-
cross section or ligament). Thus, it takes into account the original size
ergy per unit of new separation area that is made available at
of the crack but ignores any crack extension that may occur during the
the front of an ideal crack in an elastic solid during a virtual
test.
increment of forward crack extension.
DISCUSSION—2 Crack strength is analogous to the ultimate tensile
strength, as it is based on the ratio of the maximum load to the
DISCUSSION—This force concept implies an analytical model for
minimum cross-sectional area at the start of the test. E 338, E 602
which the stress-strain relations are regarded as elastic. The preceding
definition of G applies to either static cracks or running cracks. From
crack-tip opening displacement (CTOD), d, [L]—the crack
past usage, G is commonly associated with linear-elastic methods of
displacement resulting from the total deformation (elastic
analysis, although the J (see J-integral) also may be used for such
plus plastic) at variously defined locations near the original
analyses. E 1823
(prior to load application) crack tip.
−3/2 −1
crack-extension resistance, K [FL ], G [FL ]or J
R R R
−1 DISCUSSION—In common practice, d is estimated for Mode 1 by
[FL ]—a measure of the resistance of a material to crack
inference from observations of crack displacement nearby or away, or
extension expressed in terms of the stress-intensity factor, K;
both, from the crack tip. E 1290
crack-extension force, G; or values of J derived using the
J-integral concept. crack-tip plane strain—a stress-strain field (near the crack
tip) that approaches plane strain to the degree required by an
DISCUSSION—See definition of R-curve. E 561
empirical criterion.
crack length, a [L]—See crack size and surface crack length.
DISCUSSION—For example, in Mode 1, the criterion for crack-tip
Also see crack length in the Description of Terms. For
plane strain given by Test Method E 399 requires that plate thickness,
example, in the C(T) specimen, a is measured from the line 2
B, must be equal to or greater than 2.5 (K/s ) . E 399
YS
connecting the bearing points of load application; in the
crack-tip plane stress—a stress-strain field (near the crack tip)
...
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