Search results
Results from the WOW.Com Content Network
In materials science, fatigue is the initiation and propagation of cracks in a material due to cyclic loading. Once a fatigue crack has initiated, it grows a small amount with each loading cycle, typically producing striations on some parts of the fracture surface.
Basquin's law of fatigue states that the lifetime of the system has a power-law dependence on the external load amplitude, , where the exponent has a strong material dependence. [1] It is useful in expressing S-N relationships .
Low cycle fatigue (LCF) has two fundamental characteristics: plastic deformation in each cycle; and low cycle phenomenon, in which the materials have finite endurance for this type of load. The term cycle refers to repeated applications of stress that lead to eventual fatigue and failure; low-cycle pertains to a long period between applications.
The method successively extracts the smaller interruption cycles from a sequence, which models the material memory effect seen with stress-strain hysteresis cycles. [1] This simplification allows the number of cycles until failure of a component to be determined for each rainflow cycle using either Miner's rule to calculate the fatigue damage ...
There are three mechanisms acting in thermo-mechanical fatigue Creep is the flow of material at high temperatures; Fatigue is crack growth and propagation due to repeated loading; Oxidation is a change in the chemical composition of the material due to environmental factors. The oxidized material is more brittle and prone to crack creation.
Static fatigue describes how prolonged and constant cyclic stress weakens a material until it breaks apart, which is called failure. [1] Static fatigue is sometimes called "delayed fracture". [ 2 ] The damage occurs at a lower stress level than the stress level needed to create a normal tensile fracture. [ 2 ]
Within the branch of materials science known as material failure theory, the Goodman relation (also called a Goodman diagram, a Goodman-Haigh diagram, a Haigh diagram or a Haigh-Soderberg diagram) is an equation used to quantify the interaction of mean and alternating stresses on the fatigue life of a material. [1]
Surface fatigue is a process in which the surface of a material is weakened by cyclic loading, which is one type of general material fatigue. Fatigue wear is produced when the wear particles are detached by cyclic crack growth of microcracks on the surface. These microcracks are either superficial cracks or subsurface cracks.