Analysis of Stress & Strain near the Crack Tip

Stress-strain distribution near the crack tip was studied in this paper, with the emphasis on the fracture process zone (FPZ). Assuming the distribution of stress within the FPZ is linear, adopted three different consistency namely elimination of the plastic singularity at the crack tip, the balance of energy at the onset of crack motion and the crack opening angle, the general features of FPZ was analyzed and the correct length of FPZ and normal stress distribution within FPZ were determined. Similarly, the normal strain within the FPZ was obtained assuming the distribution of strain within the FPZ is linear. The maximum normal stress and strain locates in the juncture of FPZ and plastic region near the crack tip and their value does not depend on external loading. According to the length of FPZ and the continuous distribution of stress and strain, the stress and strain near the crack tip were revised applied amendatory J-Q theory. The determination of stress & strain distribution near the crack tip is a good supportive aid for research of crack propagation mechanism of oil & gas transmission pipeline.