Analysis of Growing Ductile Cracks Using Computer Image Processing

Abstract

This paper is concerned with a study of growing crack-tip behaviors in ductile materials using the hybrid experimental and numerical method by means of a computer image processing technique. Here, a displacement field near a crack tip is first measured by the image processing technique. Combined with a finite element technique, the strain, the stress, the near-crack-tip J-integral, and the crack-tip singular field are evaluated from the measured displacement field. In this procedure, elastic unloading phenomena occurring around a growing crack tip, which may play important roles in the near-crack-tip behaviors, are also evaluated and are taken into account in evaluating the near-crack-tip J-integral. The present method is applied to the analyses of a growing ductile crack in a tensile (CT) specimen made of Type 304 stainless steel. The transition behaviors of the crack-tip singular field, the elastic unloading, and the near-crack-tip J-integral in accordance with crack growth are discussed in detail through the comparison between experimental and theoretical results.