Durability Topics

Abrasion Hardness
Resistance to abrasive wear.
Bending Stress
Stress on the cross-sectional area of a beam due to the bending moment of the beam under load.
Breaking Stress
Also known as the ultimate tensile strength. This is the maximum stress that can be applied to a material.
Brittle Crack Propagation
A very sudden propagation of a crack with the absorption of no energy except that stored elastically in the body.
Brittle Fracture
Separation of a solid with little or no macroscopic plastic deformation.
The tendency of a material to fracture without first undergoing significant plastic deformation.
Climate Chamber
A test facility that can recreate different climatic conditions, often extreme conditions that allow a component, assembly or complete system to be tested to ensure it will perform correctly.
Compressive Stress
Stress on the cross-sectional area of a body normal to the compression force acting on the body
A fracture type discontinuity characterized by a sharp tip and high ratio of length and width to opening displacement.
Crack Growth Analysis
Fatigue analysis technique that assumes the existence of a crack or flaw and looks at this propagation.
Critical Resolved Shear Stress
The shear stress, resolved within a slip plane and direction, which is required to initiate slip.
Cycle Counting
Cycle counting is used to summarize lengthy, irregular load-versus-time histories by providing the number of times cycles of various amplitudes occur.
Cyclic Loading
The repeated loading and unloading of a structure to determine the fatigue lifetime.
Durability Books
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Durability Calculations
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Durability Conversions
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Durability Source Code
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Durability Weblinks
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Engine Tuning to Increase Durability
The adjustment, modification or design of internal combustion engines to increase durability.
An important mode of failure of engineering components subjected to dynamic stresses.
Fatigue Analysis
The anlysis of a particular design to understand how durable it will be over it′s lifetime.
Fatigue Chunks
Thick three-dimensional particles exceeding 50 microns indicating severe wear.
Fatigue Corrosion
The process in which a metal fractures prematurely under conditions of simultaneous corrosion and repeated cyclic loading at lower stress levels or fewer cycles than would be required in the absence of the corrosive environment.
Fatigue Failure
Failure occurs after a period of time even in cases of low stress, the component appears to get tired.
Fatigue Life
Number of cycles of fluctuating stress and strain of a specified nature that a material will sustain before failure occurs.
Fatigue Limit
In fatigue testing, the number of cycles which may be withstood without failure at a particular level of stress.
Fatigue Notch Factor
Ratio of fatigue strength of a specimen with no stress concentration to fatigue strength of a specimen with a notch or other stress raisers.
Fatigue Ratio
Ratio of fatigue strength or fatigue limit to tensile strength.
Fatigue Resistance
The ability of a material to withstand repeated and varying loads.
Fatigue Strength
Magnitude of fluctuating stress required to cause failure in a fatigue test specimen after a specified number of cycles of loading.
Fatigue Strength Reduction Factor
An alternate term for fatigue notch factor.
Fatigue Test
A method for determining the behaviour of materials under fluctuating loads.
Fibre Stress
Stress through a point in a part in which stress distribution is not uniform.
Flow Stress
The shear stress required to cause plastic deformation of solid metals.
Fracture Stress
True stress generated in a material at fracture.
Heat Cracking
A pattern of small, irregular cracks, that result from local heating of an object.
Hoop Stress
Circumferential stress in a cylindrically shaped part as a result of internal or external pressure.
Hot Crack
A crack that forms due to internal stresses developed from shrinkage during solidification of a metal casting.
Level Cross Counting
One count is recorded each time the positive sloped portion of the load exceeds a present level above the reference load, and each time the negative sloped portion of the load exceeds a present level below the reference load.
Local Stress Relieving
Stress relieving heat treatment of a specific portion of a structure.
Mean Stress
Algebraic difference between maximum and minimum stress in one cycle of fluctuating loading, as in a fatigue test.
Nominal Stress
Stress calculated on the basis of the net cross section of a specimen without taking into account the effect of geometric discontinuities such as holes, grooves, fillets, etc.
Normal Stress
Stress acting perpendicular to an imaginary plane cutting through an object.
Operating Stress
Stress imposed on a part in service.
Application of high fluctuating loads at the beginning of a fatigue test and lower loads toward the end.
Peak Counting
This method identifies the occurrence of a relative maximum or minimum load value.
Peierls Stress
The stress required to move a dislocation.
Proof Stress
Stress that will cause a specified permanent deformation.
Rainflow Analysis
A method of representing a random signal by various numbers of sinusoids that would produce the same amount of fatigue damage.
Residual Stress
Internal stress in a material often resulting from thermal or mechanical straining.
Shear Stress
Stress in the cross-sectional plane of a material that is in the same plane as the shearing force acting on it.
Simple-Range Counting
Range is the difference between two successive reversals. The range is positive when a valley is followed by a peak. The range is negative when a peak is followed by a valley.
SN Curve
High-cycle fatigue situations, materials performance is commonly characterized by an S-N curve, also known as a Wöhler curve . This is a graph of the magnitude of a cyclic stress (S) against the logarithmic scale of cycles to failure (N).
Static Failure
Failure when stress exceeds tensile strength in a single pass.
Step Stressing
stresses in a series of pre-selected increments.
Strain-Life Analysis
Models plasticity and low cycle fatigue.
Defined as the force per unit area of cross-section.
Stress Amplitude
One-half the range of fluctuating stress developed in a specimen in a fatigue test.
Stress Concentration
A condition in which a stress distribution has high localized stresses; usually induced by an abrupt change in the shape of the part (eg holes, corners, necks).
Stress Corrosion
Preferential attack of areas under stress in a corrosive environment, where such an environment alone would not have caused corrosion.
Stress Corrosion Cracking
Material deterioration due to cracking, by being under static stress either applied or residual.
Stress Intensity Factor
A scale factor to define the magnitude of the crack-tip stress field.
Stress Raisers
Changes in contour or discontinuities in a structure that cause local increases in stress.
Stress Ratio
Ratio of minimum stress to maximum stress in one cycle of loading in a fatigue test.
Stress Relaxation
Rate of reduction of stress in a material due to creep.
Stress Relieving
Heating to a suitable temperature, holding long enough to reduce residual stresses and then cooling slowly enough to minimize the development of new residual stresses.
Stress Resultant
A system of forces which is statically equivalent to a stress distribution over an area.
Stress Rupture Strength
Alternative name for Creep Rupture Strength.
Stress-Life Analysis
Analysis technique works best for high cycle fatigue.
Stress-Rupture Test
A tension test performed at constant temperature, the load being held at such a level as to cause rupture.
Stress-Strain Diagram
Graph of stress as a function of strain.
Stress-Strain Ratio
Stress divided by strain at any load or deflection, below the elastic limit of a material it is equal to tangent modulus of elasticity.
Tensile Stress
Stress acting on the cross-sectional area of a body normal to the tension force acting on the body.
Thermal Fatigue
A type of fatigue failure that introduces the cyclic stresses by fluctuating thermal stresses.
Thermal Stress
A residual stress introduced within a body resulting from a change in temperature.
Torsional Stress
Shear stress developed in a material subjected to a specified torque in torsion test.
True Stress
The load applied to a material divided by the cross sectional area over which it acts.
Viscous Stresses
The components of the stress tensor when the pressure, i.e., the mean of the three normal stresses, has been subtracted out from each of the normal stresses.
Working Stress
The allowable stress considered to be safe in the design of part. It is the ultimate stress of the material divided by a safety factor.

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Subjects: Materials Mechanical Engineering Noise & Vibration