Revision for “Fatigue Wear” created on November 10, 2021 @ 02:28:52
<em>Fatigue wear </em>is a type of wear where a number of cycles is needed to generate debris. The fatigue process in metals may induce the generation of surface and subsurface cracks, which after a critical number of cycles results in a severe damage, such as large fragments leaving the surface[1,2]. Two mechanisms of fatigue wear are distinguished: high- and low-cycle fatigue. In high-cycle fatigue, the number of cycles before failure is high, so the component life is relatively long. The cracks in this case are generated due to preexisting micro defects in the material, close to which the local stress may exceed the yield value, even though nominally the macroscopic contact is in the elastic regime. Accumulation of plastic strain around inhomogeneities is a precursor for initiation of a crack. In the low-cycle fatigue, the number of cycles before failure is low, so the component fails fast. In this mode, plasticity is induced each cycle and the wear particle is generated over the course of accumulated cycles. The wear debris is not generated at the first cycles, but only the shallow grooves due to plastic deformation are formed, as discussed in. After a critical number of cycles, the plastic strain exceeds a critical value and the fracture takes place. There are the three stages in crack propagation: crack initiation, growth and post-critical stage, when the catastrophic failure occurs. Most of the lifetime of the component is occupied by the first stage, with the sizes of initial cracks around 2-3 μm and lower.  Bhushan B. Principles and Applicaion of Tribology. New York: A Wiley-Interscience Publication; 1999.  Barrois W. Repeated Plastic Deformation as a Cause of Mechanical Surface Damage in Fatigue, Wear, Fretting-Fatigue, and Rolling Fatgiue. 1979;79.  Bhushan B. Modern Tribology Handbook. Columbus: CRC Press; 2001.  Padilla H, A., Boyce, B.,L. A Review of Fatigue Behavior in Nanocrystalline Metals. 2010;50.  Sangid M, D. The Physics of Fatigue Crack Initiation. 2013;57.  Hokkirigawa K, Kato, K. An Experimental and Theoretical Investigation of Ploughing. Cutting and Wedge formation During Abasive Wear. 1988;21.  Lawson L, Chen, E.Y., Meshii, M. Near-Threshold Fatigue: A Review 1999;21.  Mughrabi H. Microstructural Fatigue Mechanisms: Cyclic Slip Irreversibility, Crack Initiation, Non-Linear Elastic Damage Analysis. 2013;57.
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