ASM Metals HandBook Vol. 8 - Mechanical Testing and Evaluation
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Polystyrene, 30% glass reinforced 8.3 1.2 …
…
Polyphenylene sulfide, 40% glass reinforced 7.7 1.12 …
…
Fluorocarbon, ETFE and ECTFE; glass reinforced 7.6 1.1 …
…
Melamines, cellulose electrical 7.6 1.1 6.9
1.0
Cedar (Eastern red) 6.2 0.9 …
…
Polyimides, unreinforced 4.8 0.70 3.1
0.45
Polyesters, thermoset, cast, rigid 4.5 0.65 1.0
0.15
Acetal, homopolymer; unreinforced 3.6 0.52 …
…
Acrylics, cast, general purpose 3.4 0.50 2.4
0.35
Acrylics, moldings 3.4 0.50 1.6
0.23
Nylon, mineral reinforced 3.4 0.5 …
…
Polystyrene, general purpose 3.4 0.50 3.2
0.46
Styrene acrylonitrile; unreinforced 3.4 0.50 2.8
0.40
Nylons; general purpose 3.3 0.48 1.9
0.28
Polyphenylene sulfide, unreinforced 3.3 0.48 …
…
Polystyrene, impact grades 3.2 0.47 1.0
0.15
Epoxies, cast 3.1 0.45 0.3
0.05
Polycarbonate, unreinforced 3.1 0.45 2.3
0.34
ABS 2.9 0.42 2.0
0.29
Acetal, copolymer; unreinforced 2.8 0.41 …
…
Phenylene oxide based resins; unreinforced 2.6 0.38 2.5
0.36
ABS/polycarbonate 2.6 0.37 …
…
Acrylic/PVC 2.6 0.37 2.3
0.34
Polyaryl sulfone 2.6 0.37 …
…
Polysulfone; unreinforced 2.5 0.36 …
…
Polyether sulfone 2.4 0.35 …
…
ABS/PVC, rigid 2.3 0.33 …
…
ABS/polysulfone (polyaryl ether) 2.2 0.32 …
…
Allyl diglycol carbonate 2.1 0.30 …
…
Fluorocarbon, PTFCE 2.1 0.30 1.3
0.19
Fluorocarbon, ETFE and ECTFE; unreinforced 1.7 0.24 …
…
ABS/polyurethane 1.5 0.22 1.1
0.16
Polypropylene, general purpose 1.5 0.22 1.1
0.16
Polymethylpentene 1.4 0.21 …
…
Fluorocarbon, PVF 1.4 0.2 1.2
0.17
Vinylidene chloride copolymer; oriented 1.38 0.20 …
…
Polypropylene, high impact 0.9 0.13 …
…
Polyethylene, high molecular weight 0.69 0.1 …
…
Fluorocarbon, FEP 0.5 0.07 0.3
0.05
Fluorocarbon, PTFE 0.5 0.07 0.3
0.04
Vinylidene chloride copolymer; unoriented 0.48 0.07 …
…
Polybutylene, homopolymer 0.25 0.036 0.23
0.034
Polybutylene, copolymer 0.23 0.034 0.08
0.012
Polyacrylate, unfilled 0.20 0.29 …
…
Polyethylenes, low density 0.19 0.027 0.14
0.020
PVC, PVC-acetate, nonrigid 0.021
0.003 0.0027
0.0004
PET, polyethylene terephthalate; ECTFE, ethylene tetrafluoroethylene; ETCFE, ethylene
chlorotrifluoroethylene; PVC, polyvinyl chloride; PVF, polyvinyl formal; FEP, fluorinated ethylene propylene;
PTFE, polytetrafluoroethylene
Glossary of Terms
A
A-basis
Mechanical property value above which at least 99% of the population of values is expected to fall, with
a confidence of 95%. Also called A-allowable. See also B-basis, S-basis, and typical basis.
abrasion
Roughening or scratching of a surface due to abrasive wear.
abrasive wear
The removal or displacement of material from a surface when hard particles slide or roll across the
surface under pressure. The particles may be loose or may be part of another surface in contact with the
surface being worn. Contrast with adhesive wear.
accepted reference value
A value that serves as an agreed-on reference for comparison and which is derived as the following: (1)
a theoretical or established value, based on scientific principles, (2) an assigned value, based on
experimental work of some national or international standards organization, or (3) a consensus value,
based on collaborative experimental work under the auspices of a scientific or engineering group. When
the accepted reference value is the theoretical value, it is sometimes referred to as the “true” value.
accuracy
(1) The agreement or correspondence between an experimentally determined value and an accepted
reference value for the material undergoing testing. The reference value may be established by an
accepted standard (such as those established by ASTM), or, in some cases, the average value obtained
by applying the test method to all the sampling units in a lot or batch of the material may be used. (2)
The extent to which the result of a calculation or the reading of an instrument approaches the true value
of the calculated or measured quantity. Compare with precision.
adhesive wear
The removal or displacement of material from a surface by the welding together and subsequent
shearing of minute areas of two surfaces that slide across each other under pressure. In advanced stages,
may lead to galling. Contrast with abrasive wear.
alligator skin
See preferred term orange peel.
angle of bend
The angle between the two legs of a specimen after bending is completed. It is measured before release
of the bending force, unless otherwise specified.
anisotropy
The characteristic of exhibiting different values of a property in different directions with respect to a
fixed reference system in the material. See also planar anisotropy
apparent area of contact
In tribology, the area of contact between two solid surfaces defined by the boundaries of their
macroscopic interface.
arbitration bar
A test bar, cast with a heat of material, used to determine chemical composition, hardness, tensile
strength, and deflection and strength under transverse loading in order to establish the state of
acceptability of the casting.
asperity
In tribology, a protuberance in the small-scale topographical irregularities of a solid surface.
average linear strain
See engineering strain.
axial strain
See uniaxial strain.
B
batch
A definite quantity of some product or material produced under conditions that are considered uniform.
A batch is usually smaller than a lot
Bauschinger effect
The phenomenon by which plastic deformation increases yield strength in the direction of plastic flow
and decreases it in other directions.
B-basis
Mechanical property value above which at least 90% of the population of values is expected to fall, with
a confidence of 95%. See also A-basis, S-basis, and typical-basis.
bearing area
The product of the pin (or hole) diameter and specimen thickness in a bearing test. See also bearing
stress.
bearing strain
The ratio of the deformation of the bearing hole, in the direction of the applied force, to the pin diameter
in a bearing test.
bearing strength
The maximum bearing stress that a material is capable of sustaining.
bearing stress
The force per unit of bearing area.
bearing test
A method of determining the response to stress (load) of metal products that are subjected to riveting,
bolting, or a similar fastening procedure. The purpose of the test is to determine the bearing strengthof
the material and to measure the bearing stress versus the deformation of the hole created by a pin or rod
of circular cross section that pierces the sheet perpendicular to the surface.
bearing yield strength
The bearing stress at which a material exhibits a specified limiting deviation from the proportionality of
bearing stress to bearing strain in a bearing test.
bend radius
(1) The inside radius of a bent section. (2) The radius of a tool around which metal is bent during testing
or fabrication.
bend test
A test for determining the relative ductility of metal that is to be formed (usually sheet, strip, plate, or
wire) or for determining soundness and toughness of metal (after welding, for example). The specimen
is usually repeatedly bent over a specified diameter through a specified angle and then unbent for a
specified number of cycles. There are four general types of bend tests, named according to the manner
in which the forces are applied to the specimen to make the bend: free bend, guided bend, semiguided
bend, and wrap-around bend.
biaxial stress
See principal stress (normal).
blanking shear test
A method used to determine the through-thickness shear strength of sheet material that involves
blanking a disk out of flat strip using a simple punch-and-die method. Alson known as punching shear
test.
breaking load
The maximum load (or force) applied to a test specimen or structural member loaded to rupture.
breaking stress
The stress at failure. Also known as rupture stress. See also fracture stress.
Brinell hardness number, HB
A number related to the applied load and to the surface area of the permanent impression made by a ball
indenter computed from the equation:
where P is applied load, kgf; D is diameter of ball, mm;and d is mean diameter of the impression, mm.
Brinell hardness test
A test for determining the hardness of a material by forcing a hard steel or carbide ball of specified
diameter into it under a specified load. The result is expressed as the Brinell hardness number.
brittle crack propagation
A very sudden propagation of a crack with the absorption of no energy except that stored elastically in
the body. Microscopic examination may reveal some deformation not noticeable to the unaided eye.
Contrast with ductile crack propagation.
brittle fracture
Separation of a solid accompanied by little or no macroscopic plastic deformation. Typically, brittle
fracture occurs by rapid crack propagation with less expenditure of energy than for ductile fracture.
buckling
A compression phenomenon that occurs when, after some critical level of load, a bulge, bend, bow,
kink, or other wavy condition is produced in a beam, column, plate, bar, or sheet structural element.
bulk modulus
See bulk modulus of elasticity.
bulk modulus of elasticity (K)
The measure of resistance to change in volume; the ratio of hydrostatic stress to the corresponding unit
change in volume. This elastic constant can be expressed by the equation:
where K is bulk modulus of elasticity, σ
m
is hydrostatic or mean stress tensor, p is hydrostatic pressure,
and β is the coefficient of compressibility. Also known as bulk modulus, compression modulus,
hydrostatic modulus, and volumetric modulus of elasticity.
button
That part of a weld, including all or part of the weld nugget, that tears out in the destructive testing of a
spot, seam, or projection welded specimen.
C
capacity
In tensile testing machines, the maximum load and/or displacement for which a machine is designed.
Some testing machines have more than one load capacity. These are equipped with accessories that
allow the capacity to be modified as desired.
catastrophic wear
Rapidly occurring or accelerating surface damage, deterioration, or change of shape caused by wear to
such a degree that the service life of a part is appreciably shortened or its function is destroyed.
caustic cracking
A form of stress-corrosion cracking most frequently encountered in carbon steels or iron-chromium-
nickel alloys that are exposed to concentrated hydroxide solutions at temperatures of 200 to 250 °C (400
to 480 °F). Also known as caustic embrittlement.
caustic embrittlement
See preferred term caustic cracking.
cavitation damage
Erosion of a solid surface through the formation and collapse of cavities or bubbles in an adjacent liquid
that contains vapor and/or gas.
cavitation erosion
See preferred term cavitation damage.
central tendency of data
In statistics this is described by the central limit theorem. This theorem states the fact that if one draws
samples of size nfrom the population and calculates the mean of these samples, the means will form a
distribution that tends toward normality regardless of the form of the original sample distribution.
chafing fatigue
Fatigue damage initiated in a surface damaged by rubbing against another body. See also fretting.
Charpy test
An impact test in which a V-notched, keyhole-notched, or U-notched specimen, supported at both ends,
is struck behind the notch by a striker mounted at the lower end of a bar that can swing as a pendulum.
The energy that is absorbed in fracture is calculated from the height to which the striker would have
risen had there been no specimen and the height to which it actually rises after fracture of the specimen.
Contrast with Izod test.
chevron pattern
A fractographic pattern of radial marks (shear ledges) that looks like nested letters “V,” sometimes
called a herringbone pattern. Chevron patterns are typically found on brittle fracture surface in parts
whose widths are considerably greater than their thicknesses. The points of the chevrons can be traced
back to the fracture origin.
chord modulus
The slope of the chord drawn between any two specific points on a stress-strain curve. Compare with
secant modulus. See also modulus of elasticity.
cleavage
The tendency of a material to cleave or split along definite crystallographic planes.
cleavage fracture
A fracture, usually of a polycrystalline metal, in which most of the grains have failed by cleavage,
resulting in bright reflecting facets. It is one type of crystalline fracture and is associated with low-
energy brittle fracture. Contrast with shear fracture.
coefficient of compressibility
See bulk modulus of elasticity.
coefficient of friction (μ)
The dimensionless ratio of the force (F) between two bodies to the normal force (N) pressing these
bodies together: μ (or f) = (F/N)
coefficient of thermal expansion
(1) Change in unit of length (or volume) accompanying a unit change of temperature, at a specified
temperature. (2) The linear or volume expansion of a given material per degree rise of temperature,
expressed at an arbitrary base temperature or as a more complicated equation applicable to a wide range.
compression modulus
See bulk modulus of elasticity.
compression test
A method for assessing the ability of a material to withstand compressive loads.
compressive modulus
The ratio of compressive stress to compressive strain below the proportional limit. Theoretically equal
to Young's modulus determined from tensile experiments.
compressive strength
Maximum compressive stress a material is capable of developing. With a brittle material that fails in
compression by fracturing, the compressive strength has a definite value. For ductile, malleable, or
semiviscous materials (which do not fail in compression by a shattering fracture), the value obtained for
compressive strength is an arbitrary value dependent on the degree of distortion that is regarded as
effective failure of the material.
compressive stress
A stress that causes an elastic body to deform (shorten) in the direction of the applied load. Contrast
with tensile stress.
compressometer
Instrument for measuring change in length over a given gage length caused by application or removal of
a force. Commonly used in compression testing of metal specimens.
constant-life fatigue diagram
A plot (usually on rectangular coordinates) of a family of curves, each of which is for a single fatigue
life (number of cycles), relating alternating stress, maximum stress, minimum stress, and mean stress.
The constant-life fatigue diagram is generally derived from a family of S-N curves, each of which
represents a different stress ratio for a 50% probability of survival. See also nominal stress, maximum
stress, minimum stress, S-N curve, fatigue life, and stress ratio.
continuous use temperature
The maximum temperature at which material may be subjected to continuous use without fear of
premature thermal degradation.
conventional strain
See engineering strain.
conventional stress
See engineering stress.
corrosion fatigue
Cracking produced by the combined action of repeated or fluctuating stress and a corrosive environment
at lower stress levels or fewer cycles than would be required in the absence of a corrosive environment.
corrosive wear
Wear in which chemical or electrochemical reaction with the environment is significant. Compare with
oxidative wear.
covalent bond
A bond in which two atoms share a pair of electrons. Contrast with ionic bond.
crack arrest
The temporary or permanent cessation of crack extension.
crack extension (Δ
a
)
An increase in crack size. See also crack length (depth), effective crack size, original crack size, and
physical crack size.
crack-extension force (G)
The elastic energy per unit of new separation area that would be made available at the front of an ideal
crack in an elastic solid during a virtual increment of forward crack extension. See also J-integral.
crack-extension resistance (K
R
)
A measure of the resistance of a material to crack extension, expressed in terms of the stress-intensity
factor, the crack-extension force, or values of Jderived using the J-integral concept.
crack-growth rate
Rate of propagation of a crack through a material due to statically or dynamically applied load.
crack length (depth) (a)
In fatigue and stress corrosion cracking, the physical crack size used to determine the crack growth rate
and the stress-intensity factor. For the compact-type specimen, crack length is measured from the line
connecting the bearing points of load application. For the center-cracked-tension specimen, crack length
is measured from the perpendicular bisector of the central crack.
crack-mouth-opening displacement (CMOD)
See crack-opening displacement.
crack-opening displacement (COD)
On a K
Ic
, specimen, the opening displacement of the notch surfaces at the notch and in the direction
perpendicular to the plane of the notch and the crack. The displacement at the tip is called the crack-tip-
opening displacement (CTOD); at the mouth, it is called the crack-mouth-opening displacement
(CMOD).
crack-plane orientation
An identification of the plane and direction of a fracture in relation to product geometry. This
identification is designated by a hyphenated code, the first letter(s) representing the direction normal to
the crack plane and the second letter(s) designating the expected direction of crack propagation.
crack size (a)
A lineal measure of a principal planar dimension of a crack. This measure is commonly used in the
calculation of quantities descriptive of the stress and displacement fields. In practice, the value of crack
size is obtained from procedures for measurement of physical crack size, original crack size, or effective
crack size, as appropriate to the situation under consideration. See also crack length.
crack-tip-opening displacement (CTOD)
See crack-opening displacement.
crack-tip plane strain
A stress-strain field, near a crack-tip, that approaches plane strain to the degree required by an empirical
criterion.
crazing
Region of ultrafine cracks, which may extend in a network on or under the surface of a resin or plastic
material. May appear as a white band. Often found in a filament-wound pressure vessel or bottle. In
many plastics, craze growth precedes crack growth, often generating additional strength because crazes
are load bearing.
creep
Time-dependent strain occurring under stress. The creep strain occurring at a diminishing rate is called
primary or transient creep; occurring at a minimum and almost constant rate, secondary or steady-rate
creep; that occurring at an accelerating rate, tertiary creep.
creep rate
The slope of the creep-time curve at a given time determined from a Cartesian plot.
creep recovery
The time-dependent decrease in strain in a solid, following the removal of force. Recovery is usually
determined at a constant temperature.
creep-rupture strength
The stress that will cause fracture in a creep test at a given time in a specified constant environment.
Also known as stress-rupture strength.
creep-rupture test
A method of evaluating elevated temperature durability in which a tension specimen is stressed under
constant load until it breaks. Data recorded commonly include initial stress, time to rupture, initial
extension, creep extension, and reduction in area at the fracture. Also known as stress-rupture test.
creep strain
The time-dependent total strain (extension plus initial strain) produced by applied stress during a creep
test.
creep strength
The stress that will cause a given creep strainin a creep test at a given time in a specified constant
environment.
creep stress
The constant load in a creep test divided by the original cross-sectional area of the specimen.
creep test
A method of determining the extension of metals under a given load at a given temperature. The
determination usually involves the plotting of time-elongation curves under constant load.
cross linking
With thermosetting and certain thermoplastic polymers, the setting up of chemical links between the
molecular chains. When extensive, as in most thermosetting resins, cross linking makes an infusible
supermolecule of all the chains. In rubbers, the cross linking is just enough to join all molecules into a
network.
crushing test
(1) A radial compressive test applied to tubing, sintered-metal bearings, or other similar products for
determining radial crushing strength(maximum load in compression). (2) An axial compressive test for
determining quality of tubing, such as soundness of weld in welded tubing.
crystalline
That form of a substance comprised predominantly of (one or more)crystals, as opposed to glassy or
amorphous.
crystalline defects
The deviations from a perfect three-dimensional atomic packing that are responsible for much of the
structure-sensitive properties of the materials. Crystal defects can be point defects (dislocations) or
surface defects (vacancies), line defects (dislocations), or surface defects (grain boundaries).
crystalline fracture
A pattern of brightly reflecting crystal facets on the fracture surface of a polycrystalline metal, resulting
from cleavage fracture of many individual crystals. Contrast with fibrous fracture and silky fracture, See
also granular fracture.
cup fracture (cup-and-cone fracture)
A mixed-mode fracture, often seen in tensile-test specimens of a ductile material, where the central
portion undergoes plane-strain fracture and the surrounding region undergoes plane-stress fracture. One
of the mating fracture surfaces looks like a miniature cup; it has a central depressed flat-face region
surrounded by a shear lip. The other fracture surface looks like a miniature truncated cone.
cupping test
A mechanical test used to determine the ductility and drawing properties of sheet metal. It consists of
measuring the maximum depth of bulge that can be formed before fracture. The test is commonly
carried out by drawing the test piece into a circular die by means of a punch with a hemispherical end.
See also Erichsen cup test, Olsen cup test, and Swift cup test.
cycle
In fatigue, one complete sequence of values of applied load that is repeated periodically. The symbol N
represents the number of cycles. See also S-N curve.
cyclic loads
Loads that change value by following a regular repeating sequence of change.
D
decarburization
Loss of carbon from the surface layer of a carbon-containing alloy due to reaction with one or more
chemical substances in a medium that contacts the surface.
deflection temperature under load (DTUL)
The temperature at which a simple cantilever beam deflects a given amount under load. Formerly called
heat distortion temperature.
deformation
A change in the form of a body due to stress, thermal change, change in moisture, or other causes.
Measured in units of length.
deformation curve
See stress-strain diagram.
deformation energy
See strain energy.
density
The mass per unit volume of a solid material.
design of experiments (DOE)
A methodology involving statistically designed experiments in which the character and sequence of
individual experiments are planned in advance so that data are taken in a way that will provide the most
unbiased and precise results commensurate with the available time and money. The chief classes of
statistically designed experiments are: (1) blocking designs to remove the effect of background variables
from the experimental error, (2) factorial designs, in which all levels of each factor in an experiment are
combined with all levels of every other factor, and (3) response surface designs, which determine the
empirical relation between the factors (independent variables)and the response (performance variable).
diamond pyramid hardness test
See Vickers hardness test
dilatometer
An instrument for measuring length or volume changes in a solid during heating and subsequent cooling
or isothermal holding.
dimensional stability
Ability of a plastic part to retain the precise shape in which it was molded, fabricated, or cast.
dimpled rupture
A fractographic term describing ductile fracture that occurs through the formation and coalescence of
microvoids along the fracture path. The fracture surface of such a ductile fracture appears dimpled when
observed at high magnification and usually is most clearly resolved when viewed in a scanning electron
microscope. See also ductile fracture.
discontinuous yielding
The nonuniform plastic flow of a metal exhibiting a yield point in which plastic deformation is
inhomogeneously distributed along its length. Under some circumstances, it may occur in metals not
exhibiting a distinct yield point, either at the onset of or during plastic flow.
dislocation
A linear imperfection in a crystalline array of atoms. Two basic types are recognized: (1) an edge
dislocation corresponds to the row of mismatched atoms along the edge formed by an extra, partial
plane of atoms within the body of a crystal; (2) a screw dislocation corresponds to the axis of a spiral
structure in a crystal, characterized by a distortion that joins normally parallel planes together to form a
continuous helical ramp (with a pitch of one interplanar distance) winding about the dislocation. Most
prevalent is the so-called mixed dislocation, which is any combination of an edge dislocation and a
screw dislocation.
dislocation density
The total length of dislocation lines per unit volume, or the number of dislocation lines that cut through
a unit cross-sectional area.
displacement
The distance that a chosen measurement point on a cracked specimen displaces normal to the crack
plane as the crack grows. See also crack-opening displacement and crack plane orientation.
distortion
Any deviation from an original size, shape, or contour that occurs because of the application of stress or
the release of residual stress.
double-shear test
A shear test having two stationary, shear blades and one moving one and that uses solid round bars as
test specimens.
ductile crack propagation
Slow crack propagation that is accompanied by noticeable plastic deformation and requires energy to be
supplied from outside the body. Contrast with brittle fracture.
ductile fracture
Fracture characterized by tearing of metal accompanied by appreciable gross plastic deformation and
expenditure of considerable energy. Contrast with brittle fracture.
ductility
The ability of a material to deform plastically before fracturing. Measured by elongation or reduction in
area in a tensile test, by height of cupping in a cupping test, or by the radius or angle of bend in a bend
test. See also malleability.
durometer hardness
Measure of the indentation hardness of plastics. It is the extent to which a spring-loaded steel indenter
protrudes beyond the pressure foot into the material.
dynamic mechanical measurement
A technique in which either the modulus and/or damping of a substance under oscillatory load or
displacement is measured as a function of temperature, frequency, or time, or a combination thereof.
dynamic modulus
The ratio of stress to strain under cyclic conditions (calculated from data obtained from either free or
forced vibration tests, in shear, compression, or tension).
dynamic recovery
A process occurring in hot working of metals in which a fine subgrain structure forms within the
elongated grains due to annihilation of dislocations due to easy cross slip and climb. It results in a
lowering of the flow stress. Dynamic recovery, as opposed to dynamic recrystallization that occurs in
hot working, occurs in metals of high stacking fault energy such as aluminum, αiron, and most bcc
metals.
dynamic strain aging
A behavior in metals in which solute atoms are sufficiently mobile to move toward and interact with
dislocations. This results in strengthening over a specific range of elevated temperature and strain rate.
E
edge distance
The distance from the edge of a bearing specimen to the center of the hole in the direction of applied
force. See also bearing test.
edge distance ratio
The ratio of the edge distance to the pin diameter in a bearing test.
edge strain
Transverse strain lines or Lüders lines ranging from 25 to 300 mm (1 to 12 in.) in from the edges of cold
rolled steel sheet or strip.
effective crack size (a
e
)
The physical crack size augmented for the effects of cracking plastic deformation. Sometimes the
effective crack size is calculated from a measured value of a physical crack size plus a calculated value
of a plastic-zone adjustment. A preferred method for calculation of effective crack size compares
compliance from the secant of a load-deflection trace with the elastic compliance from a calibration for
the type of specimen.
effective yield strength
An assumed value of uniaxial yield strength that represents the influence of plastic yielding on fracture-
test parameters.
elastic calibration device
A device for use in verifying the load readings of a testing machine consisting of an elastic member(s)
to which loads may be applied, combined with a mechanism or device for indicating the magnitude (or a
quantity proportional to the magnitude) of deformation under load.
elastic constants
The factors of proportionality that relate elastic displacement of a material to applied forces. See also
modulus of elasticity, bulk modulus of elasticity, shear modulus, and Poisson's ratio.
elastic deformation
A change in dimensions directly proportional to and in phase with an increase or decrease in applied
force.
elastic energy
The amount of energy required to deform a material within its elastic range of behavior, neglecting
small heat losses due to internal friction. The energy absorbed by a specimen per unit volume of
material contained within the gage length being tested. It is determined by measuring the area under the
stress-strain curve up to a specified elastic strain. See also modulus of resilience and strain energy.
elastic hysteresis
See preferred term mechanical hysteresis.
elastic limit
The maximum stress which a material is capable of sustaining without any permanent strain
(deformation) remaining on complete release of the stress. Compare with proportional limit.
elastic recovery
Amount the dimension of a stressed elastic material returns to its original (unstressed) dimension on
release of an applied load. In hardness testing, the shortening of the original dimensions of the
indentation upon release of the applied load.
elastic resilience
The amount of energy absorbed in stressing a material up to the elastic limit; or, the amount of energy
that can be recovered when stress is released from the elastic limit.
elastic strain
See elastic deformation.
elastic strain energy
The energy expended by the action of external forces in deforming a body elastically. Essentially, all the
work performed during elastic deformation is stored as elastic energy, and this energy is recovered upon
release of the applied force.
elasticity