Thermal Residual Stress In Short Fiber Reinforced Metal Matrix Composites And Its Effect On The Mechanical Behavior

In metal matrix composites,thermal residual stresses will arise due to GET (Coefficient of Thermal Expansion) mismatch between matrix and fiber during cooling. Thermal residual stresses in short fiber reinforced metal matrix composites (SFRMMC) can reach a high level and have a significant effect on the mechanical properties of composites. In this paper,three dimensional elastoplastic finite element analyses were used to study the thermal residual stresses in SFRMMC and its effect systematically.With the interfacial property,fiber's orientation and reciprocity of fibers considered,the thermal residual stresses in -Al2O3/Al-5.5Mg, -Al2O3/Al-5.5Zn and -Al2O3/Al-12Si alloy composites were calculated and analysed. Three models were used,one fiber model,two fibers model and oblique fiber model. The tensile stress -strain curves of composites were also simulated. Based on the energy equivalence principle,the formula that could predict the modulus of elasticity of SFRMMC was educed by considering the effects of thermal residual stresses and fiber's orientation.Calculating and analysis indicate that the thermal residual stresses in SFRMMC are spatially non-uniform. This has a significant effect on the mechanical properties of composites. The simulative stress-strain were in good quantitative agreement with experiments as compared with the curves that didn't included the thermal residual stresses. Comparison of the simulative curves with the experimental curves indicate that,when the volume fraction of fiber is lesser one fiber model is accurate,but when the volume fraction of fiber is biggish two fibers model or the more practical models should be used. The predicted value of the modulus of elasticity of the three composites is also keeping with the measured result very well. Predicting of the expressions has higher precision.