Probabilistic analysis of weld cracks in center-cracked tension specimens

摘要

This paper describes the development of a probabilistic methodology for fracture-mechanics analysis of weld cracks in a center-cracked tension (CCT) specimen. It involves elastic-plastic analyses to predict J-integral, statistical models of uncertainties in loads and material properties, and standard computational methods of structural reliability theory for probabilistic analysis. Eighty-one deterministic finite element analyses were performed for a wide variety of crack size, material mismatch factors, and weld geometric parameters to develop approximate equations for the J-integral of a CCT specimen and were subsequently applied for probabilistic fracture evaluaitons. Both fast probability integrators, such as first- and second-order reliability methods, and Monte Carlo simulation were used to determine the probabilistic characteristics of the J-integral. The same methods were used later to predict the failure probability based on initiation of crack growth. Numerical results are presented to illustrate the proposed methodology. The effects of mismatch factors on both deterministic and probabilistic response characteristics were examined. The results indicated that the tensile properties of both base and weld materials should be accounted for when calculating J. These mismatch factors have a significant effect on the probabilistic characteristics of J and failure probability.