Effects of thermal stress and imperfect interfacial bonding on the mechanical behavior of composites subjected to off-axis loading

Metal matrix composites exhibit inelastic response due to the viscoplasticity of matrix, and imperfect interfacial bonding will decrease the flow stress sharply. The present study develops the generalized model of cells (GMC) to predict mechanical behavior of unidirectional metal matrix composites with imperfect interfacial bonding, which is subjected to off-axis loading. The model incorporates viscoplastic model for the matrix and interfacial debonding model for the fiber/matrix interface. The effects of fiber volume fraction and thermal residual stress on stress–strain response of composites are also discussed. Results show that stress–strain response influenced by fiber cross-section shape becomes more evident with the increase of fiber off-axis angle. Similar stress–strain response can be found in the early stage of loading regardless of the thermal residual stress. However, the effect of thermal residual stress on the stress–strain behavior of composites with imperfect interfacial bonding is closely dependent on fiber off-axis angle in the plastic stage.

Research highlights▶ Square fiber provides more stiffening behavior than circular fiber. ▶ Increasing fiber volume fraction will decrease the stiffness behavior. ▶ The effect of thermal residual stress depends on fiber off-axis angle.