What is fatigue ?
Component failure is caused by (metal) fatigue, which is a physical phenomenon. Fatigue is a type of progressive failure characterized by the beginning and spread of cracks to an unstable structure. This can also occur due to mechanical abuse or overloading etc.
Which variables have an impact on fatigue ?
Loads, geometry, and material are the three main elements that influence fatigue.
Fatigue tests can be classified based on a number of factors. For example, the following is a common classification:
Test requirements include:
Engineers and technicians use fatigue testing to anticipate a part’s or component’s durability in a variety of operating environments. Fatigue tests are used to determine the total number of load cycles to failure, as well as to assess the decline in stiffness and strength of materials due to repetitive loading. Repeated tension-tension, compression-compression, tension-compression, or other cyclic loading combinations are used to perform fatigue tests. Loading is given through the actuator and measured with the load cell. The test loads are usually recorded using a data logger that collects data from thousands of inputs from equipment installed on the test sample, such as strain gauges, pressure gauges, load cells, and LVDTs, etc. A representative model or loading module is applied repeatedly until the safe life of the structure is demonstrated or failures occur that need to be corrected.
Load cells, strain gauges, and displacement gauges are mounted on the structure to check that the proper load has been applied. Load cells that are most commonly used for fatigue testing are strain gauge based high fatigue rated load cells.