User:R123J456/Static fatigue

Static Fatigue
Static fatigue describes '''how repetitive cyclic stress weakens a material until it breaks apart, which is called failure.  It is sometimes called "delayed fracture".  This damage happens at a smaller stress level than the stress level needed to create a normal''' tensile fracture. Static fatigue has to do with plastic deformation or crack growth. For example, repeated stress can create small cracks that grow and eventually break apart plastic , glass , and ceramic '''materials. The material reaches failure faster by increasing cyclic stress. Static fatigue varies with material type and environmental factors such as moisture presence and''' temperature.

Applications
Static fatigue tests can estimate a material’s lifetime and hardness to different environments '''. However, measuring a static fatigue limit takes a long time, and it is hard to measure a material’s true static fatigue limit with full certainty .'''

Stress corrosion cracking
Stress corrosion cracking (SCC) happens when a stressed material is in a corrosive (chemically destructive) environment. One example of SSC embrittlement is when moisture increases static fatigue effects in glass. SCC is also seen in hydrogen embrittlement, embrittlement of some polymers, and more.

Plastic Deformation (Plastic Flow)
Plastic deformation happens when stresses flatten, bend, or twist a material until it no longer returns to its original shape. '''This can create several cracks in the material and decrease its lifetime. '''

Examples of Static Fatigue and Stresses on Materials
Plastic pipes under water or other fluids experience hydrodynamic forces resulting in fatigue. The pipes reach failure sooner with higher temperature or increased exposure to aggressive substances. '''For static fatigue tests, rotating machines apply weight on the material under study causing it to bend in different directions. '''