材料期刊网

2.5维机织复合材料已有较为广泛的应用,目前对该类复合材料强度理论的研究还相对较少。根据2.5维机织复合材料拉伸破坏的细观机理,基于单向复合材料的三维Hoffman准则,建立了2.5维机织结构复合材料拉伸破坏准则,通过对2.5维机织复合材料3种结构24个试件进行拉伸试验,与计算预测结果的对比表明了本文建立的强度准则的合理性。研究表明,纤维拉伸断裂是2.5维机织复合材料拉伸破坏的主要原因;相比基于最大应力准则、Hashin准则建立的强度准则,基于Hoffman准则建立的强度准则综合考虑了纤维在外载荷作用下各应力分量对纤维断裂破坏的影响,其预测结果与实际试验结果更为接近;在其他条件不变情况下,随纱线取向角增大,纱线拉伸断裂应力呈非线性降低。随纱线纤维体积含量增加,纱线拉伸断裂应力成线性增加。

Although 2.5D woven composites are now in wide use,the failure theory of them has not been fully studied.Based on the Hoffman criteria for 3D and the micro-scale tensile failure mechanism of 2.5D,the failure criteria of 2.5D woven composites are deduced.To verify the failure criteria,24 samples of 2.5D woven composites with three different structures were selected for tensile tests.The experiment results are in good agreement with the outcome of the failure criteria.It is also found that fiber rupture is the reason of the composites failure;the failure criteria based on the Hoffman criteria is relatively close to the experiment results comparing with that deduced from the Hashin criteria or maximum stress criteria.The failure stress of fiber decreases in non-linear ways with the increase in the orientation angle of the fiber,and decrease in a linear way with the decrease in the fiber relative volume.