Crack Opening Displacement Measurement of Surface Crack using Digital Image Correlation Method

Abstract

The effective stress intensity factor range for surface crack in A7075 aluminum alloy under tensile or bending load was determined based on the displacement distribution around the crack tip obtained from the digital image correlation method. Calculation of the opening stress at the crack tip from the effective stress intensity factor range indicated that crack closure occurred under all experimental conditions. The log-log plots of crack growth rate versus the effective stress intensity factor range showed that the data for tensile and bending loads collapsed into a factor of two scatter band. It was also clarified that the crack growth life can be predicted with an error of about ±20% when the modified Paris law is applied to calculate the crack growth life.