Damage evolution and fracture behaviors of continuous graphite fiber reinforced aluminium matrix composites subjected to quasi-static tensile loading

According to the microstructure of the continuous graphite fiber reinforced aluminium matrix (CF/Al) composites, the micromechanical finite element model was established based on the representative volume element (RVE) with different fibre arrangements. The progressive damage and fracture behaviors of the CF/Al composites under axial tensile condition were investigated by quasi-static tensile testing and numerical simulation method. The results show that the axial tensile modulus and strength calculated by the micromechanical model with the diagonal quadrilateral fiber arrangement agree well with the experimental results, while the fracture strain is underestimated. At the first tensile stage, the interface damage initiates and accumulates. With the increase of strain, the interface damage induces the local interfacial debonding and matrix alloy failure at the middle stage. At the last stage, the occurrence of fiber failure leads to the eventual fracture of the composites, which results in a fracture surface with coexistence of matrix tearing and fiber pull out. According to the micromechanical calculation results, the influence of interfacial strength and stiffness on the axial tensile behavior is inapparent in the case of insufficient fiber strength, while the axial mechanical properties of the composite are primarily determined by the in-situ fiber ultimate strength.