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A crack growth equation is used for calculating the size of a fatigue crack growing from cyclic loads. The growth of a fatigue crack can result in catastrophic failure, particularly in the case of aircraft. When many growing fatigue cracks interact with one another it is known as widespread fatigue damage. A crack growth equation can be used to ...
[2] [3] The law provides a mathematical model to predict the number of cycles to failure (N) based on the applied stress amplitude (). A High Cycle Fatigue Test is used to determine material behaviour under repetitive cyclic loads. This test aims to establish the stress-cycles-to-failure characteristics of materials, primarily utilising an ...
Also, in the presence of a steady stress superimposed on the cyclic loading, the Goodman relation can be used to estimate a failure condition. It plots stress amplitude against mean stress with the fatigue limit and the ultimate tensile strength of the material as the two extremes. Alternative failure criteria include Soderberg and Gerber. [36]
One noteworthy event in which the failure was a result of LCF was the 1994 Northridge earthquake. Many buildings and bridges collapsed, and as a result over 9,000 people were injured. [ 6 ] Researchers at the University of Southern California analyzed the main areas of a ten-story building that were subjected to low-cycle fatigue.
Being a power law relationship between the crack growth rate during cyclic loading and the range of the stress intensity factor, the Paris–Erdogan equation can be visualized as a straight line on a log-log plot, where the x-axis is denoted by the range of the stress intensity factor and the y-axis is denoted by the crack growth rate.
Concrete cone failure – Failure mode of anchors in concrete submitted to tensile force; Concrete degradation – Damage to concrete affecting its mechanical strength and its durability; Earthquake – Sudden movement of the Earth's crust; Fatigue – Initiation and propagation of cracks in a material due to cyclic loading
A cyclic model (or oscillating model) is any of several cosmological models in which the universe follows infinite, or indefinite, self-sustaining cycles. For example, the oscillating universe theory briefly considered by Albert Einstein in 1930 theorized a universe following an eternal series of oscillations, each beginning with a Big Bang and ending with a Big Crunch; in the interim, the ...
When cyclic stresses are applied to a material, even though the stresses do not cause plastic deformation, the material may fail due to fatigue. Fatigue failure is typically modeled by decomposing cyclic stresses into mean and alternating components. Mean stress is the time average of the principal stress.