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Glossary of Materials Testing

A B C D E F G H I K L M
N O P R S T U V W Y Z
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A
Accuracy
Actuator
Adherence
Adherence Index
Adjustment
Alpha Rockwell Hardness
Anisotropic or Anisotropy
Anvils
Average Value
Axial Strain
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B
Bagley Correction
Balance
Bend Test
Bending Strength
Bond Strength
Break Detector
Break Elongation
Breaking Load
Breaking Strength
Brittle Failure (Impact)
Bulk Modulus of Elasticity
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C
Calibration
Capillary Rheometer
CEAST: Compagnia Europea Apparecchi Scientifici Torino (CEAST)
Channel
Cleavage Strength
Climbing Drum Peel Test
Coefficient of Elasticity
Cohesive Strength
Complex Modulus
Compliance
Composite Channel
Compressibility
Compressibility and Recovery Test
Compression Fatigue
Compression Set
Compression Test
Compression-Deflection Test
Compressive Deformation
Compressive Strength
Compressive Yield Strength
Constant Amplitude
Control Loop
Control Mode
Control Pendant
Controller
Crack Propagation
Creep
Creep and Stress-Relaxation Test
Creep Limit
Creep Rate
Creep Recovery
Creep Rupture Strength
Creep Strength
Creep Test
Crosshead
Crosshead (Impact)
Crush Resistance
Crushing Load
Crushing Strength
Impact Charpy
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D
Damping
Deflection to Maximum Load (Impact)
Deformation Energy
Deformation Under Load
Delamination Strength
Denier
Derived Channel
Dies (Rheology)
Double Shear Round
Drift
Drop Height (Impact)
Drop Weight Assembly
Dry Strength
Ductile Failure (Impact)
Ductility
Dynamic Creep
Dynamic Mechanical Analysis (DMA)
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E
EASL
Eccentricity of Loading
Edge Tearing Strength
Elastic Hysteresis
Elastic Limit
Elastic Limit, Apparent
Elasticity
Elongation
Embrittlement
Endurance
Energy
Energy to Failure (Impact)
Energy to Maximum Load (Impact)
Energy to Yield (Impact)
Engineering Strain
Engineering Stress
Error
Event Detector
Extension
Extensometer
Extrusion
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F
Fatigue
Fatigue Life
Fatigue Limit
Fatigue Notch Factor
Fatigue Ratio
Fatigue Strength
Fatigue Strength Reduction Factor
Fatigue Test
Fiber Stress
Filler
Flag (Impact)
Flex Resistance
Flexural Modulus of Elasticity
Flexural Strength
Flexure Test
Flow Stress
Fracture Initiation
Fracture Stress
Fracture Test
Fracture Toughness
Frequency (Impact Data Acquisition)
Frequency Response
Frequency, Natural
Full-Scale
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G
Gauge Length
Gauge Width
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H
Hardness
Hardness Test
Harmonic Frequency (Impact)
Hooke's Law
Hysteresis Loop
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I
Impact Energy
Impact Strength
Impact Test
Impact Velocity
In Vitro
Incipient Damage Point
Inertial Peak (impact)
Initial Tension
Isotropic
Izod (Impact)
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K
Kink Test
Knot Strength
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L
LASE
Limits (Operational)
Linear Density
Linear Interpolation
Live Displays
Load
Load at Failure (Impact)
Load at Yield (Impact)
Load Cell
Load Frame
Load Protect
Load String
Load-Deflection Diagram
Loop Shaping
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M
Maximum (yield) Load (Impact)
Maximum Fiber Stress
Maximum Load (Impact)
Mean Stress
Measurement
Measurement Consistency
Melt Flow Rate (MFR, MVR)
Melt Index
Minimum Bend Radius
Modulus
Modulus in Bending
Modulus of Elasticity
Modulus of Rigidity
Modulus of Rupture
Modulus of Strain Hardening
Modulus of Toughness
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N
Necking
Nominal Modulus
Nominal Stress
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O
Offset Yield Strength
Operating Stress
Out of Tolerance (OOT)
Outer Fiber Strain Factor
Outer Fiber Stress Factor
Overstressing
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P
Parallel Length
Peak Maximum/Minimum
Peel Extension
Peel Factor
Peel Length
Peel Resistance
Peel Strength
Physical Measurement
Piezoelectric
Plastic
Plastic Deformation
Plastic Strain Ratio
Plasticity
Plasticity Number
Poisson's Ratio
Precycling
Preload
Pressure Transducer
Prompt Workspace
Prompted Test
Proof Stress
Proportional Limit
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R
Ramp
Rate of Strain Hardening
Rationalization
Rationalized Transducer
Real Channel
Rebound Test
Recovery
Recovery Test
Reduction of Area
Relative Modulus
Relaxation
Repeatability
Residual Elongation
Result
Rheology Testing
Ringing
Rupture Resistance
Rupture Strength
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S
Safety Shield
Sample
Secant Modulus of Elasticity
Self-Identification
Set Point
Shear Modulus of Elasticity
Shear Rate
Shear Strength
Shear Stress
Shock Absorbers
Slack
S-N Diagram
Soft-Keys
Specimen
Specimen Protect
Splitting Resistance
Springback
Standalone Mode
Stiffness
Stop Blocks
Strain
Strain Energy
Strain Hardening Exponent
Strain Pacing
Strain Point
Strain Rate
Strain Rate (Adaptive)
Strain Relaxation
Straining Rate
Strength Coefficient
Strength Reduction Ratio
Stress
Stress Amplitude
Stress Concentration Factor
Stress Rate
Stress Ratio
Stress Relaxation
Stress Rupture Strength
Stressing Rate
Stress-Strain Diagram
Stress-Strain Ratio
Striker (Impact)
Stripping Strength
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T
Table (Impact)
Tangent Modulus of Elasticity
Tear Length
Tear Resistance
Tearing Strength
Tenacity
Tensile Impact Test
Tensile Modulus of Elasticity
Tensile Strength
Tensile Testing
Tension Set
Tension Test
Tex
T-Grooved Baseplate (Impact)
Thermoplastic
Thermosetting
Time for Rupture
Torsion Test
Torsional Deformation
Torsional Modulus of Elasticity
Torsional Strain
Torsional Strength
Torsional Stress
Total Absorbed Energy (Impact)
Total Deflection (Impact)
Total Energy (Impact)
Toughness
Transducer
Transverse Strain
True Strain
True Stress
Tup
Tup Insert
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U
Ultimate Elongation
Ultimate Strength
Uncertainty of Measurement
Upper Yield Strength
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V
Velocity Slowdown (Impact)
Verification
Versachannel
Virtual Measurement
Viscoelasticity
Viscosity
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W
Wet Strength
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Y
Yield Point
Yield Point Elongation
Yield Strength
Yield Strength Elongation
Yield Value
Young's Modulus
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Z
Zero Suppression
Zone

Hardness Test

Simply stated, hardness is the resistance of a material to permanent indentation. It is important to recognize that hardness is an empirical test and therefore hardness is not a material property. This is because there are several different hardness tests that will each determine a different hardness value for the same piece of material. Therefore, hardness is test method dependent and every test result has to have a label identifying the test method used.

Hardness is, however, used extensively to characterize materials and to determine if they are suitable for their intended use. All of the hardness tests described in this section involve the use of a specifically shaped indenter, significantly harder than the test sample, that is pressed into the surface of the sample using a specific force. Either the depth or size of the indent is measured to determine a hardness value.

Why Use a Hardness Test?

  • Easy to perform
  • Quick - 1 to 30 seconds
  • Relatively inexpensive
  • Non-destructive
  • Finished parts can be tested - but not ruined
  • Virtually any size and shape can be tested
  • Practical QC device - incoming, outgoing

The most common uses for hardness tests is to verify the heat treatment of a part and to determine if a material has the properties necessary for its intended use. Establishing a correlation between the hardness result and the desired material property allows this, making hardness tests very useful in industrial and R&D applications.

Hardness Scales

There are five major hardness scales:
  • Brinell - HB
  • Knoop - HK
  • Rockwell - HR
  • Shore - HS
  • Vickers - HV

Each of these scales involve the use of a specifically shaped diamond, carbide or hardened steel indenter pressed into the material with a known force using a defined test procedure. The hardness values are determined by measuring either the depth of indenter penetration or the size of the resultant indent. All of the scales are arranged so that the hardness values determined increase as the material gets harder. The hardness values are reported using the proper symbol, HR, HV, HK, etc. indicating the test scale performed.

Five Determining Factors

The following five factors can be used to determine the correct hardness test for your application.

  • Material - grain size, metal, rubber, etc.
  • Approximate Hardness - hardened steel, rubber, etc.
  • Shape - thickness, size, etc.
  • Heat Treatment – through or casehardened, annealed, etc.
  • Production Requirements - sample or 100%