Fatigue Damage and Life Evaluation of Particle-Reinforced Aluminum Matrix Composites of A16061/Al_2O_3 and AI6061/SiC under Uniaxial and Multiaxial Loading Conditions

摘要

Fatigue damage and life prediction of particle metal matrix composites (PMMCs) under uniaxial and multiaxial loading conditions were investigated. Three PMM composite materials of A16061/Al_2O_3/20p-T6, A16061/Al_2O_3/22p-T6 and A16061/SiC/17w-T6 tested under tensile, torsion, and combined tension-torsion fatigue cycling were evaluated with various fatigue damage models. The fatigue damage models of Smith-Watson-Topper (SWT), Ellyin (E), Brown-Miller (BM), Fatemi-Socie (FS) and Varvani (V) were compared for their capability to assess the fatigue damage of materials undergoing various loading conditions. Both critical plane models of BM and FS on the other hand collapsed the fatigue damage data in a reasonably narrower band under uniaxial and multiaxial loading conditions. Over both the low-cycle and high-cycle fatigue regimes, SWT approach and E energy model resulted in a wide scatter range of correlated damage data.Fatigue life predication results were further evaluated by implementing material-dependent coefficients that factored in the effects of the particle reinforcement in the earlier developed Varvani model. The critical plane-energy approach incorporated the critical plane as the plane of crack initiation and early stage of crack growth. The strain energy density was calculated on the critical plane incorporating stress and strain components acting on the plane. Material dependent parameters in this damage approach, enabled an accurate damage assessment of PMMCs as the effect of the shear and normal fatigue properties was accounted in the damage model by means of α and β terms to estimate fatigue damage of PMMCs in the presence of metal-matrix strain-life data. The critical plane-energy approach successfully predicted fatigue lives of PMMCs within a factor of ±3 under various loading conditions. This approach successfully evaluated fatigue damage values versus fatigue lives within a narrower band for both uniaxial and multiaxial loading conditions as compared with other damage approaches studied in this paper.