FINITE ELEMENT SIMULATION AND EXPERIMENTAL ANALYSIS ON FATIGUE BEHAVIOR OF SiC_n/Al CO–CONTINUOUS COMPOSITES

摘要

The co–continuous ceramic/metal composite (referred to as C4 composites) are becoming an important class of materials as the result of the development of a number of new techniques for fabricating composites with interpenetrating macrostructures. In this paper, the fatigue endurance behaviors of three three–dimensional (3–D) continuous SiC ceramic network reinforced ZL111 Al alloy composites (T6–treated SiC_n/ZL111Al) were simulated by the finite element method (FEM). The finite element simulation showed that the stress concentration, due to the presence of continuous SiC ceramic network reinforcements, produces controlled crack growth and higher stresses, which are related to regular energy release by the material during fracture. The need for higher stresses for a crack to propagate reveals the material's microstructural strength. Experimental analysis showed fatigue life for specimen was 4.8×10~5 cycles for 200 MPa, R=-1.0, and 6.5×10~5 cycles for 95 MPa, R=-0.05. The number of cycles to failure predicted numerically is higher than the experimental one. This difference is attributed mainly to an upper stage of fatigue crack growth, particularly, the interaction between fatigue crack growth and growth that cannot be accounted for in the numerical model.