Plastic deformation and fracture of AlMg6/CNT composite: A damage evolution model coupled with a dislocation-based deformation model

Understanding the plastic deformation and fracture behavior of Carbon nanotube (CNT)-reinforced aluminum composites is crucial for determining the factors controlling their strength and ductility. This article presents a novel approach by proposing a coupled micromechanical dislocation-based constitutive model combined with the Gurson-Tvergaard-Needleman (GTN) damage evolution model. The objective of this research is to accurately predict the load-displacement behavior of an AlMg6/CNT composite, which is manufactured through accumulative roll bonding (ARB), from yield to fracture. The study investigates the correlations between the number of ARB passes, which affects the dislocation density of the matrix, and the distribution of CNTs in the composite, with the GTN parameters. The analysis reveals that the volume fraction of void nucleating particles (fN) is a critical parameter influencing the ductility of the composite ductility. Initially, due to CNT agglomeration, they act as nucleation sites for damage, resulting in an increase in fN and a decrease in ductility. However, as the number of ARB passes increases, leading to a homogeneous CNT distribution, fN decreases, and CNTs contribute to improved strength and ductility of the composite. The proposed model accurately predicts the load-displacement curve of the composite during uniaxial tensile testing, taking into account the effect of ARB passes. The research findings provide insights for future extensions of the GTN model, aimed at enhancing its theoretical framework and applicability in the field.