Investigation of an Updated Continuum Damage Model in the DBTT Region

Abstract

With the investigation of influence of the stress triaxiality on the fracture properties, an updated continuum damage model is proposed and realized by FEA to evaluate the temperature effect and the strain rate effect on the fracture properties in the ductile and brittle transition temperature (DBTT) region. The updated continuum damage model based on the fracture energy density per unit crack propagation area in Fracture Process Zone (FPZ) is proposed, in which the fracture energy density as the function of the stress triaxiality, temperature and strain rate is taken as the indicator of the critical damage factor, considering the unique fracture stress or the fracture strain as fracture criterions are not effective to describe the fracture properties for both the ductile fracture and the brittle fracture co‐exist and compete. With the user subroutine in ABAQUS, Finite Element Simulations are performed with the realization of the updated continuum damage model. From the simulation results, it is found that the fracture process of uni‐axial tension in the DBTT region depends on both the temperature and the strain rate. With the reduction of the temperature or the increment of the strain rate the fracture process is changed from the ductile fracture with much plastic deformation to the brittle fracture with typical brittle fracture properties.