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.
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.
Corrosion fatigue is fatigue in a corrosive environment. It is the mechanical degradation of a material under the joint action of corrosion and cyclic loading. Nearly all engineering structures experience some form of alternating stress, and are exposed to harmful environments during their service life.
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 ]
Vibration fatigue is a mechanical engineering term describing material fatigue, caused by forced vibration of random nature. An excited structure responds according to its natural-dynamics modes, which results in a dynamic stress load in the material points. [ 1 ]
When a material is cyclically strained, a plot of stress against strain shows loops forming from the smaller interruption cycles. At the end of the smaller cycle, the material resumes the stress-strain path of the original cycle, as if the interruption had not occurred. The closed loops represent the energy dissipated by the material. [1]
Fatigue testing is a specialised form of mechanical testing ... Fatigue tests are used to obtain material data such as the rate of growth of a fatigue crack ...