Cf/Al复合材料横向拉伸微观损伤与力学性能的有限元分析

Micromechanical Analysis on the Effect of Fiber Content on Transverse Tensile Behavior and Damage Evolution of Unidirectional Carbon Fiber Reinforced Aluminum Composites

根据石墨纤维增强铝基复合材料(Cf/Al基复合材料)显微组织特征构建了其代表性体积单元(RVE),通过基体合金的延性损伤模型和纤维的最大应力失效模型,建立了基于内聚力界面模型的细观力学有限元模型并结合试验结果验证了其可靠性,在此基础上分析了纤维含量对复合材料横向拉伸损伤演化与力学行为的影响。结果表明,基于正六边形纤维排布RVE建立的细观力学模型能够准确预测复合材料横向拉伸力学性能。横向拉伸过程中首先发生界面损伤,随应变增加界面损伤累积,引起局部界面失效并诱发附近基体合金的损伤与失效,最终导致复合材料横向开裂,拉伸断口呈现界面脱粘和基体合金撕裂共存的微观形貌。提高纤维含量增加了界面数量和面积,从而降低了复合材料横向拉伸弹性模量和极限强度。

The microscopic damage and macroscopic mechanical behavior of Cf/Al composites with different fiber content were investigated by micromechanical and experimental method.Representative Volume Element(RVE)with diagonal regular quadrilateral and regular hexagonal fiber arrangements were established according to the composites microstructure.The damage behavior of matrix alloy was described by ductile damage model and the fiber fracture behavior was simulated using a maximum stress failure criterion.And then a micromechanical finite element model based on cohesive interface was established and the calculation reliability was verified by the experimental results.Based on the micromechanical model,the damage evolution and fracture behavior of the composites with different fiber content were analyzed.It is found that the micromechanical model with regular hexagonal fiber arrangement can predict the elastoplastic behavior of composites accurately.At the first stage,the initial interface damage is accumulated with the increase of strain and induce some local interface failure.At the middle stage,some local matrix damage is initialed and developed near the failed interface.At the last stage,the interface and matrix failure results in the transverse cracking of the composites.The tensile fracture surface exhibits the characteristic of interfacial debonding and matrix tearing.The transverse tensile modulus and ultimate strength of the composite are decreased with the increase of fiber content,which can be attributed to the occurrence of more interface quantity and interface area.