横向压缩载荷下CF/Al复合材料微观损伤演化与断裂力学行为

针对真空压力浸渗制备的单向碳纤维增强铝基复合材料(CF/Al复合材料),采用细观力学数值模拟和实验相结合的手段研究了其在横向压缩载荷下的损伤演化与断裂力学行为,并分析了界面结合性能和纤维体积分数对复合材料横向压缩力学性能的影响。结果表明:基于纤维对角正方形分布RVE建立的细观力学有限元模型,可以较好地计算预测复合材料横向压缩变形力学行为。压缩变形初期界面首先发生损伤和失效现象,进而诱发界面附近基体合金的局部损伤;随压缩应变增加,界面和基体损伤逐渐发展并导致纤维的失效,复合材料横向压缩断口呈现出界面脱粘和纤维断裂共存的微观形貌。复合材料横向压缩弹性模量和极限强度随着界面强度增大而增大,而受界面刚度的影响较小;在相同界面性能条件下,复合材料横向压缩极限强度和弹性模量均随纤维体积分数的增大而减小。

Microscopic damage evolution and fracture behaviors of CF/Al composites subject to transverse compression loading

The unidirectional carbon fiber reinforced aluminum matrix composites(CF/Al composites)were prepared by vacuum assisted pressure infiltration method.The damage evolution and fracture mechanical behaviors of the composites under transverse compression condition were investigated by means of micromechanical numerical simulation and experimental methods.The effects of interfacial bonding properties and fiber volume fraction on the transverse compression behavior of the composites were analyzed.The results show that the micromechanical finite element model based on a diagonal square RVE can well predict the mechanical behavior of the composite under transverse compression.At the initial deformation stage,the interfacial damage and failure initiate at first,and then induce the local damage of the matrix alloy near the interface.With the increase of strain,the matrix damage accumulates gradually and leads to the local fiber failure.The microscopic fracture morphology of the composite presents the coexistence of interfacial debonding and fiber fracture.The transverse compressive elastic modulus and ultimate strength increase with the increase of interfacial strength,while the influence of interfacial stiffness is unobvious.Under the same interfacial property conditions,the ultimate compressive strength and elastic modulus of the composites decrease with the fiber volume fraction increasing.