Combined experimental-numerical investigation of fretting fatigue crack initiation

This study investigated the fretting fatigue crack initiation behavior of titanium alloy, Ti-6Al-4V. Tests were conducted to generate fretting fatigue failures from 2x10(4) to 5x10(7) cycles at 200 Hz. Fractography was employed to determine number of cycles to crack initiation, crack location and angle of crack orientation. Finite element analysis was conducted based on the experimental information in order to assess the ability of two critical plane approaches to predict fretting fatigue crack initiation behavior; the Smith-Watson-Topper critical plane parameter and the maximum shear stress range critical plane parameter. When properly formulated, these parameters predicted number of cycles to crack initiation and location of crack initiation which were in agreement with the experimental counterparts. However, these two parameters predicted different orientation angles of crack initiation at the contact surface. Based on the observations of orientation angles, the combined experimental-numerical approach showed that the mechanism for fretting fatigue crack initiation was governed by the maximum shear stress range on the critical plane. (C) 2001 Elsevier Science Ltd. All rights reserved.