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材料测试和力学测量名词定义
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A
Abrasion Resistance
The ability of a material to withstand surface wear due to rubbing against another surface
Adherence
The measure of the bond between a coating and a substrate
Adhesion
Adhesion is the molecular attraction exerted between bodies in contact
Adhesiveness
Defined by Adhesive stress. A = F/S where F is the force perpendicular to the bond and S is the surface area of the bond
Amorphous Polymer
A polymer with an irregular molecular chain and no crystallinity
Apparent Bending Modulus
Used for material that are too flexible for a standard bending test. The sample is supported on a cantilever beam and deflected by a set angle. Deflection, angle and specimen dimensions are used for calculations
Apparent Shear Rate
Calculated by 4Q/p R3 where Q is the volumetric flow rate (m3/s) and R is the radius (m) of the capillary
Apparent Viscosity
The viscosity of a fluid, measured at a given shear rate at a fixed temperature
Axial Strain
Strain in the direction in which the force is applied, ie; on the same axis
B
Bending Modulus
The modulus of elasticity applicable to the bending of a sample; defined as Stress / Strain
Bending Stress
Force per cm² acting on point on the sample length when a force is applied at that point
Bending Test
A sample is supported at both ends and a compressive force is applied to the middle of the sample.
Blend
A combination of two or more polymer chains having different features, that are not bonded to each other
Bond Strength
A measure of the stress required to separate a layer of material from the base to which it is bonded
Break Detector
Used to define the parameter that determines if a sample has broken. Two categories of sharp break, where the force drops quickly or a gradual break where the force reduces gradually.
Break Force
Force at which a break is defined
Break Load
Load at which a break is defined
Break Strength
Force at which a break is defined divided by sample width
Brittleness
A material which has a tendency to fracture without appreciable deformation
Bulk Modulus
An elastic constant relating mean stress to volumetric strain
Burst Strength
The ability of a material to resist rupture by pressure, sample dimensions and probe dimensions are required
C
Capillary Viscometer
Measures the time of flow of a measured volume of solution through a capillary tube under the force of gravity is compared with the time taken for the same volume of pure solvent, or of another liquid of known viscosity to flow through the same capillary
Chord
A chord of a curve is a geometric line segment whose end points both lie on the curve. A secant or a secant line is the line extension of a chord
Chord Modulus
The chord modulus is the slope of the chord drawn between any two specified points on the stress-strain curve
Cleavage Strength
Tensile load divided by sample width required to cause separation of an adhesive bond
Climbing Drum Peel
Fixture designed to peel bond between sandwich type material usually having one rigid and one flexible surface
Coefficient of Elasticity
An alternative term for modulus of elasticity
Coefficient of Kinetic Friction
The ratio of friction force to normal force once slippage has begun between two objects in contact
Cofficient of Static Friction
A ratio measure of how much force is required before an inert object, of a given material, at rest on another known substance, can be put into motion
Cohesive Strength
Measure of force / area of two substances that stick to each other
Cohesiveness
Stickiness
Compressiblity
The ability to be compressed
Compression
Application of a force to reduce a samples height
Compression Set
Deformation which remains in a sample after has been subjected to and released from a specific compress stress for a definite period of time at a prescribed temperature
Compressive Deflection
The distance that a sample is compressed
Compressive Deformation
Extent to which a material deforms under a crushing load
Compressive Strength
The measured resistance of a specimen to axial loading when expressed as force per unit area
Compressive Yield
The stress at which a material deforms found from the stress / strain curve
Conventional Stress
Conventional stress, as applied to tension and compression tests, is force divided by the original gauge length or height
Creep
Strain caused by stress that occurs over time
Creep Distance
Measurement of the distance a sample changes due to creep
Creep Rate
Rate of change of a sample due to creep
Creep Recovery
Measurement of the distance a sample returns to its original size after a creep test
Crush Test
Alternative name for a compression test, usually to fracture or break
Crystalline
Sample where the molecules are arranged in an irregular order
Curing Strength
Point a which a sample that requires time to cure achieves its maximum strength
Cycling
Exercising a sample between limits for a duration of fixed number times
D
Deformation
A change in dimensions of a material
Delamination Force
Force required to separate two bonded materials by a peeling action
Delamination Strength
Force required to separate two bonded materials by a peeling action divided by the sample width
Denier
Measurement of yarn size
Density Column
Device for measuring the density of plastic at 23 C
Die Swell
Die swell is a memory effect in which the polymer tries to return to its former shape after extrusion through a die
Draw Down
The effect of thinning of a extruded polymer when it leaves the die caused by the effect of gravity on the extruded polymer after the die
Ductile
Can be easily formed or shaped (opposite of brittle)
Ductility
The ability of a material to deform plastically without fracturing
Dumbbell
Preformed sample specimen for tensile testing, enabling the sample to be gripped easily and have a section of the sample formed to high tolerance dimensions
Dynamic Friction
Resistance to relative movement of two bodies that are already in motion
E
Edge Tear
In determining the edge tear resistance of a paper sample, a strip of paper is simultaneously torn at opposite edges of the strip by means of a thin, V-notch beam held in a stirrup. A tearing force is applied at a constant rate of elongation until the paper begins to tear
Elastic Limit
The point beyond which the deformation of a structure or material are no longer purely elastic
Elastic Modulus
The ratio of stress, within the proportional limit, to the corresponding strain
Elastic Strength
The force at the elastic limit dived by sample width
Elasticity
Tendency of a material to return to its original shape after it has been stretched or compressed
Elongation
Extension of a specimen which has been stretched in a test. The percentage elongation is an indication of ductility
Elongation at Fracture
Extension of a specimen reported at break
Elongation at Yield
The extension of a specimen reported at the yield point
Energy
Work required or work done during a test. The area under a force curve divided by the change in extension
Engineering Stress
Force divided by the original sample area
Events
Points placed on a graph which may be used to report load, stress, strain, time or extension
Extension
Measurement of movement of the testing machine
Extension Compensation
Ability to tare out an extension before the main test starts
Extensometer
Device to measure accurately the movement of a sample either by contacting directly on the sample or a non-contacting optical method
Extraction
Removal of one component from another as in "Insertion / Extraction test
F
Falling Dart
Device for measuring the force required to break a thin film material by puncturing. Uses free falling masses
Fatigue
Fatigue is a process by which a material is weakened by cyclic loading
Fatigue Duration
Effects of fatigue on a sample experienced over time
Fatigue Limit
Point at which a sample fractures or reaches a defined point during cycling
Flexural Bond
Strength of an adhesive bond between two materials determined by a flexing motion
Flexural Modulus
The ratio, within the elastic limit, of the applied stress on a test specimen in flexure to the corresponding strain
Flexural Resistance
Flexural resistance is a measurement of a material and corresponds to the maximum stress per unit area that a specimen can withstand without breaking when subjected to a bending force
Flexural Rigidity
Measurement of force required to permanently deform a sample by bending
Flexural Strength
Maximum stress developed in a specimen just before it cracks or breaks in a flexure test
Flexural Test
A bending test
Fractional Melt Index
Term used to describe polymers that have a Melt Index of less than 1
Fracturability
Food testing, a load peak or fall in the first compression cycle (bite) indicating the sample has crumbled or fractured but has not completely broken
Fracture
A break in the sample
Fracture Mode
Direction applied to a crack to open it. Open, forward or transverse shear
Fracture Test
Test ending in a sample fracture, user defined
G
Gauge Length
Unit of length which is used to calculate strain, the original sample length, height or grip separation
Gel Bloom
Test to BS757
Glass Transition
Change in an amorphous polymer from viscous to hard and relatively brittle
Green Strength
Term used to describe the strength of a polyurethane or rubber compound in the early stages of cure
Gumminess
The property of cohesiveness and stickiness
H
Hardness
Resistance to permanent deformation
Hooke's Law
The amount by which a material body is deformed (the strain) is linearly related to the force causing the deformation (the stress)
Hysteresis
The mechanical energy loss that always occurs under loading and unloading, proportional to the area between the loading and unloading load-deflection curves within the elastic range
I
Impact
The striking of one body against another
Impact Energy
The energy dissipated during an impact
Impact Strength
The force / sample dimension in an impact test
Insertion
Pushing or forcing one body in to another, as in insertion / extraction test
Intrinsic Viscosity
A measure of the capability of a polymer in solution to enhance the viscosity of the solution
J
K
Knot Strength
Measurement of the degradation of a material when a knot is formed due to compressive and tensile forces
L
Lap Shear
Shear stress that acts on a overlapped joint
Limit of Proportionality
Shear stress that acts on a overlapped joint
Linear Density
Mass per unit length
Linear Portion
Section of the stress / strain curve where increase in load is proportional to extension
Load at Yield
The load reported at point at which a specified deviation from proportionality of stress and strain occurs
Lower Yield
A lower yield is defined as being the first minima to occur after the upper yield
Lower Yield Strength
Force / area reported at a point of lower yield
M
Markers
Points placed on a graph to report load, extension, stress, strain. May be moved to recalculate values
Maximum Bending Strain
Change in length / original length and requires the span of the supports and the radius of the bend
Maximum Bending Stress
Force per unit area acting at a point along the length of a sample resulting from the bending moment applied at that point
Mean Stress
Algebraic difference between maximum and minimum stress
Melt Flow Rate
Defined as the weight of polymer in grams flowing through an aperture of specific diameter and length, with defined pressure over a 10 minute period. Also know as Melt Index
Melt Strength
A measure of the extensional viscosity of polymer melts
Melt Viscosity
A measure of the extensional viscosity of polymer melts
Melt Volume Rate
Defined as the volume of polymer in cm³ flowing through an aperture of specific diameter and length, with defined pressure over a 10 minute period
Melting Point
The temperature at which the structure of a crystalline polymer is destroyed to yield a liquid
Modulus
The physical measurement of stiffness in a material, equalling the ratio of applied load to the resultant deformation of the material
Modulus of Bending
The modulus of elasticity applicable to the bending of a beam; defined as Stress / Strain
Modulus of Elasticity
Rate of change of strain as a function of stress. The slope of the straight line portion of a stress-strain diagram
Modulus of Rigidity
Rate of change of strain as a function of stress in a specimen subjected to shear or torsion loading
Modulus of Rupture
In bending, the modulus of rupture is the bending moment at fracture divided by the section modulus
Modulus of Toughness
Work done on a unit volume of material as a simple tensile force is gradually increased from zero to the value causing rupture is defined as the Modulus of Toughness. This may be calculated as the entire area under the stress-strain curve from the origin to rupture
N
Necking
Reduction of the cross sectional area of the metal in a portion of the sample caused by stretching
Newtonian Fluid
A fluid with a constant viscosity at a given temperature regardless of the rate of shear
Nominal Stress
Stress calculated on the assumption of a uniform cross-sectional area, without defects or deformities taken in to consideration
Non-Newtonian Fluid
Fluids having viscosities that depend on the shear rate
O
Offset Yield
Point of interception on the stress / strain curve, parallel to the line of best fit offset by a defined extension
P
Peel Resistance
Another name for bond strength
Peel Strength
Force / contact area in a peel test
Percentage Elongation
Ratio of final gauge against original gauge length
Percentage Elongation at Fracture
Ratio of final gauge against original gauge length at fracture or break
Percentage Non-proportional Elongation at Fracture
Calculates the extension (as a percentage of sample gauge length / sample height) at the point where a line drawn parallel to the linear portion line, through the point of fracture, intercepts zero load
Percentage Non-proportional Elongation at Maximum Force
Calculates the elongation (as a percentage of sample gauge length / height), at which a line parallel to the linear portion line, drawn from the point of maximum force, intercepts zero load
Percentage Total Elongation at Maximum Force
Percentage total elongation at maximum force is calculated as being the extension expressed as a percentage of sample gauge-length, at the position where the load readings are highest
Plastic Deformation
Deformation that remains after the load causing it is removed. It is the permanent part of the deformation beyond the elastic limit of a material
Plasticity
The properties of a material that allow it to be shaped and to retain its shape
Poisson's Ratio
Ratio of lateral strain to axial strain in an axial loaded specimen
Preload
Load applied to a sample before it is tested to remove unwanted sample or fixture movement
Proof Strength Non-Proportional Elongation
Proof strength non-proportional elongation is calculated as being the stress at the interception of the trace with a line drawn parallel to the linear portion line, offset by the specified percentage non-proportional elongation
Proof Strength Total Elongation
Proof strength total elongation is calculated as being the stress at the specified percentage total elongation
Proof Stress
The load for a given cross sectional area under which a material must not stretch permanently beyond a specified percentage of its length
Propagation
Peel and tear testing, defined as distance moved by the two parts as they separate
Propagation Limit
Limit to which the test will drive
Puncture
Rupture caused to a sample when the force is applied at 90 degrees to the sample
Q
R
Rate of Creeping
Timed rate of deformation when the sample is subjected to a constant load at a constant temperature
Rate of Relaxation
Value of the slope of the relaxation curve at a given time
Recovery
The ability of a material to recover to its original dimensions after being subjected to a force
Relaxation
Rate at which stress reduces due to creep
Residual Extension
Difference in extension before and after a material is stressed
Resilience
The ability of a material to return to its original shape after the removal of a stress that has produced elastic strain
Rheology
The science of deformation and flow of matter
Ring Stiffness
The force required to deflect a ring or pipe sample by the percentage of its height or diameter
Rupture
When a sample bursts or is torn
Rupture Strength
Value of force to cause a rupture / sample dimensions
Rupture Stress
The failure of a specimen held under a definite constant load for a given period of time at a specific temperature
S
Seam
Joint consisting of a line formed by joining two pieces
Secant
A straight line that intersects a curve at two or more points
Secant Modulus
Slope of a line drawn from the origin to a point on the stress / strain curve
Shear
A force acting perpendicular to the longitudinal axis of a SAMPLE
Shear Rate
Shear rate is a measure of the rate of shear deformation
Shear Strength
Maximum shear stress that can be sustained by a material before rupture
Shear Stress
Normal stress is perpendicular to the designated plane, shear stress is parallel to the plane
Snap Off
Used in the testing of container lids, the action of removing the lid that exhibits a sharp drop in
Snap On
Used in the testing of container lids, the action of fitting the lid that exhibits a sharp drop in force
SPC
Statistical Process Control
Springiness
The elasticity of a material that can be stretched and returns to its original length
Stiffness
Stiffness is the resistance of an elastic body to deflection by an applied force
Strain
The amount of deformation a material experiences per unit of original length in response to stress
Strain Energy
Measure of energy absorption characteristics of a material under load up to fracture
Strain Hardening Exponent
An increase in hardness and strength caused by plastic deformation at temperatures below the recrystallization range
Strain Rate
Deformation of a specimen height or length per time
Strength
The of stress an object can endure before it breaks
Stress
Force that a material is subjected to per unit of original area
Stress Ratio
The algebraic ratio of two specified stress values in a stress cycle
Stress Relaxation
A stress-strain condition in which the stress reduces as the strain remains constant
Stringiness
The property of an adhesive which causes it to form filaments, threads, etc., when the applicator is removed from the adherend, or when transfer surfaces are separated
T
Tack Test
Applicable to adhesives. Two surfaces are contacted together at a set speed for a set duration and the force required to pull them apart is recorded
Tangent Modulus
The instantaneous slope at any point on the stress-strain curve
Tear Resistance
Resistance of a material to a force acting to initiate and then propagate a failure
Tear Strength
The force required to tear an sample divided by the sample thickness
Tenacity
Strength of fibre or yarn in terms of the ratio of breaking load and linear density
Tensile Strength
The stress in force per unit area required to break a specimen
Tension Set
Extent to which vulcanized rubber is permanently deformed after being stretched a specified amount for a short time
Tex
A unit for linear density equal to the mass in grams per 1000M
Toughness
The ability of a material to absorb energy and deform plastically before fracturing
TPA
Texture Profile Analysis. A simulation of a two bite action
True Strain
Instantaneous percentage change in specimen length. It is equal to the natural log of the ratio of length at any instant to original length
True Stress
Load divided by the area of the sample. The constant changing area is used during the test
U
Ultimate Strength
The highest force developed in a sample before break
Upper Yield
An upper yield is defined as the first maxima to occur above a specified load threshold, that persists for not less than a specified duration
Upper Yield Strength
Upper yield strength is calculated as being the reading on the stress axis at the point of the upper yield
V
Viscosity
The thickness or resistance to flow of a liquid
W
Warp
Lengthwise yarns in a fabric
Weft
Crossways yarns in a fabric
Wet Strength
Breaking force of paper when wet
Y
Yield
The stress at which a material exhibits a specified deviation from proportionality of stress and strain
Young's Modulus
The Young's Modulus result is calculated as being the gradient of the modulus line on a stress vs. strain graph
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