An Image-Based Micro-Scale Fracture Model for Weld Zone in Nuclear Pipe and Component

Abstract

The mechanical analysis of weld zone is a significant problem during the nuclear power plant design due to the fact that the material property of weld zone is complex. In most of the standards and codes, the weld zone is assumed as an effective homogeneous material. However, the weld zone is non-homogeneous at micro-scale, and the microstructure has great effect on the mechanical property, especially the fracture behaviors. Therefore, how to propose an accurate and convenient model to analyze fracture behavior of the weld zone of nuclear pipe or components becomes a major issue. The objective of present work is to develop an accurate method to investigate the fracture behavior of weld zone from the microstructure of weld zone. To achieve the objective, a double smoothed image based reconstruction method is developed to generate the finite element mesh from digital image of weld zone directly. Then a cohesive finite element framework is utilized to simulate the initiation and propagation of micro-cracks in weld zone. Moreover, a damping boundary condition is used to apply the complex loading case on the micro-scale model.