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Model for Cyclic Fatigue of Quasi‐Plastic Ceramics in Contact with Spheres
Author(s) -
Lee Kee Sung,
Jung YeonGil,
Peterson Irene M.,
Lawn Brian R.,
Kim Do Kyung,
Lee Seung
Publication year - 2000
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.2000.tb01544.x
Subject(s) - materials science , indentation , ceramic , composite material , silicon nitride , cyclic stress , contact mechanics , fracture (geology) , spheres , fracture mechanics , degradation (telecommunications) , shear (geology) , structural engineering , layer (electronics) , computer science , engineering , telecommunications , finite element method , aerospace engineering
A model of contact damage accumulation from cyclic loading with spheres and ensuing strength degradation in relatively tough, heterogeneous ceramics is developed. The damage takes the form of a quasi‐plastic zone beneath the contact, consisting of an array of closed frictional shear faults with attendant “wing” microcracks at their ends. Contact fatigue takes place by attrition of the frictional resistance at the sliding fault interfaces, in accordance with an empirical degradation law, allowing the microcracks to extend. At large numbers of cycles or loads the microcracks coalesce, ultimately into radial cracks. Fracture mechanics relations for the strength degradation as a function of number of cycles and contact load are derived. Indentation–strength data from two well‐studied coarse‐grain quasi‐plastic ceramics, a micaceous glass‐ceramic and a silicon nitride, are used to evaluate the model. Comparative tests in static and cyclic contact loading confirm a dominant mechanical component in the fatigue. At the same time, the presence of water is shown to enhance the fatigue. The model accounts for the broader trends in the strength degradation data, and paves the way for consideration of key variables in microstructural design for optimum fatigue resistance.