Author(s)

T. H. Topper and A. Vawani-Farahani

Abstract

Crack closure, crack growth rate and fatigue life changes due to compressive overloads in biaxial fatigue T. H. ~opper' & A. ~arvani-~arahani~ I Department of Civil Engineering, University of Waterloo, Waterloo, Ontario, Canada 2 Department of Mechanical, Aerospace and Industrial Engineering, Ryerson University, Toronto Ontario, Canada Abstract Crack opening stresses, crack shape, crack surface asperity heights, crack growth rates and fatigue lives were obtained at four strain ratios in a SAE 1045 steel. Measurements for uniaxial tests were made with an optical microscope while those for other strain ratios were made with a confocal scanning laser microscope. Two load histories were used, constant amplitude fully reversed straining and blocks of cycles consisting of one compressive overload cycle and a number of constant amplitude cycles. Tests were performed on standard ASTM axial specimens in uniaxial fatigue and on thin walled tubular specimens for other strain ratios. The machine used for

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