Flaw Characteristics in Dynamic Fatigue: The Influence of Residual Contact Stresses |
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Authors: | D B MARSHALL B R LAWN |
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Affiliation: | Department of Applied Physics, School of Physics, University of New South Wales, Kensington, New South Wales 2033, Australia |
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Abstract: | The effect of residual contact stresses on the dynamic fatigue response of surfaces containing indentation-induced flaws is studied. Indentation fracture mechanics is used to analyze the growth of well-defined "median/radial" cracks in combined residual (elastic/plastic) contact and applied (uniform) tensile fields, and thence to determine strength characteristics. In this way a general formulation is obtained for the fatigue strength at constant stress rate. Experimental confirmation of the essential predictions of the theory is obtained from strength tests on Vickers-indented soda-lime glass disks in water environment. It is thereby implied that residual stresses can have a significant deleterious influence on the fatigue behavior of any brittle solid whose controlling flaws have a contact history. Such effects need to be considered in the design of structural ceramics, most notably where fracture-mechanics calibrations of crack-velocity parameters are used for lifetime predictions. |
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