Development of Three-Dimensional Crack Path Prediction Model for Brittle Fracture in Welded Joint with Residual Stress, Toughness Distribution and Various Types of Welding Groove

In the present study, three-dimensional cleavage crack path prediction model is proposed. The model is based on the local fracture stress criterion in which three candidates for a cleavage plane in a computational element is assumed and the one which has maximum value of normal stress divided by local fracture stress is selected. In this model, normal stress acting on each plane is obtained by local stress intensity factor which is calculated by combination of approximate solutions where crack front non-straightness, crack surface irregularity and crack closing force acting at ridges between crack planes are considered. The model also incorporates multiaxial stress field and non-uniform toughness distribution. Therefore, this model is applied to welded joint of ESSO test where welding residual stress and non-uniform toughness distribution exist, and the predicted results of crack paths show a general agreement with the test results. Parametric study is also conducted in order to discuss the effects of applied stress, welding residual stress, toughness distribution and type of welding groove on brittle crack path behavior.