Determination of Damage Constant and Critical Damage by the Combined Experiment and FEM Using the Reference Processes

Abstract

The practical characterization algorithm is presented to find the optimized damage constants and critical damages of the traditional damage models formulated by some unknown damage constants. The flow characterization of the material SWCH45F is conducted using the combined finite element method (FEM) and experimental method, assisted by elastoplastic finite element (FE) analysis of a cylindrical tensile test with accuracy. The new concept of a critical edge length of FEs is proposed to overcome the highly negative situations caused by the remeshing during a bulk metal-forming simulation for reliable damage prediction. With accurate flow behavior and optimized numerical conditions, two examples of bulk metal-forming processes, including the tensile test and bolt heading process (all are clear in the fracture perspective), are then simulated to reveal the relationship between the damage constant and maximum damage, which is employed to determine the damage constant and the critical damage. This approach is successfully used to optimally calculate the damage constant of the generalized Huh's damage model along with the critical damage. The generality and practicality of the new approach are emphasized.