A dynamic composite rolling model based on Lemaitre damage theory

Exploring the bonding mechanisms within bimetallic composite plates throughout the cold rolling process poses a considerable challenge, especially in simulating the bonding between different metals. A novel finite element model for rolling, grounded in Lemaitre continuum damage theory, was developed using copper/aluminium composite plates as a case study to characterize the dynamic bonding process in cold rolling precisely. The model replicates the dynamics of crack formation at the metal interface, the subsequent flow of the matrix metal through these fissures, and the ensuing contact. Considering the intricate stress conditions at the interface during rolling and the influence of compression on damage accumulation, the damage evolution constant in the original Lemaitre model has been revised. This modification aims to improve the model's performance in dominant shear forces and low-stress triaxiality scenarios. The damage constant has been transformed into a variable correlating with the Lode parameter and the degree of stress triaxiality to achieve this. The model parameters were calibrated using force-displacement data derived from shear and tensile experiments. The rolling model is ingeniously designed, employing hardened layer elements as barriers to segregate the fresh metal. Experimental rolling trials and corresponding simulation analyses were performed on copper/aluminium composite plates with varying initial thickness ratios, specifically 1:2, 1.5:1.5, and 2:1. The outcomes demonstrated a high degree of agreement between the experimental and simulated profiles, including the post-rolling thickness ratios, with a maximum discrepancy of 6.1%. The finite element model effectively captured the deformation behaviour of the bimetallic material throughout the rolling process and elucidated the micromechanical processes underlying the interfacial bonding between the dissimilar metals.