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When plastic strain occurs, the service life of material decreases, often no more than 104, a.k.a., in low-cycle fatigue range. The research of low-cycle fatigue was traditioanlly done for pressure vessels, power machinery that are exposed to a heat source/sink which induces thermal expension (thermal stress) to the structure. The low-cycle fatigue is usually presented as the plastic strain in log scale against cycles to failure N also in log scale.
To add Fig 12-13, low-cycle fatigue
The result of low-cycle fatigue is near a straight line for common metal meterials such as steel and is often referred as Coffin-Manson relation:
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is the amplitude of plastic strain.
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is fatigue dutility coefficient defined by the strain intercept at 2N = 1. For common metal materials,   .
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N is the number of strain cycles to failure and 2N is the number of strain reversals to failure.
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c if called fatigue ductility exponent. For common metal materials, -0.7 < c < -0.5. A smaller c value results in a longer fatigue life.
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