材料期刊网

本文从细观力学出发,提出一种新的基于物理失效机制的细观失效准则.该准则基于Mohr-Coulomb准则并侧重考虑了压缩载荷下组分材料的损伤模式和失效机制,指出压缩失效时压应力会阻碍断裂面的剪切破坏,并深入研究了纤维压缩失效模式,在纤维折断失效准则中引入纤维折断破坏面上剪切强度的概念.采用本文提出的准则对WWFEII(the Second World Wide Failure Exercise)中单向板算例进行失效预测和定量评估,并与Puck、Pinho、Cuntze、Carrere、Tsai-Ha、Hansen和Huang准则的预测结果进行对比,表明在三向载荷下本文提出的细观失效准则在8种失效准则中拟排名第一.研究了静水压力对基体强度的影响,得出影响因子仅与单轴压缩断裂角有关的结论.探讨了WWFEII各强度准则间关于失效包线是“张开”还是“封闭”的重要分歧,认为复合材料在三向压应力状态下失效包线是否为“张开”和“封闭”没有统一的标准答案,而是与复合材料的纤维体积含量、纤维和基体的力学性能、基体随静水压力力学性能的变化及基体的单轴压缩断裂角有关.

A new micro failure criteria based on the physical failure mechanism was proposed from the standpoint of micro-mechanics.The criteria follows Mohr-Coulomb criteria,in which damage type and failure mechanism under compressive load was emphasized.This study argued that shear damage will be prevented by compressive stress on the fracture surface.Fiber compressive failure mode was also researched in depth.A concept of shear strength on fiber kinking surface was introduced in fiber kinking failure criteria.Failure prediction and quantitative evaluation for lamina in the Second World Wide Failure Exercise were carried out.The prediction results were compared with Puck,Pinho,Cuntze,Carrere,Tsai-Ha,Hansen and Huang criteria.Assessment results show that the criteria proposed in this study ranks first under tri-axial load.The effect on the strength of matrix by hydrostatic pressure was researched.The results show that influence factor is only relevant with fracture angle of matrix under single compressive load.The important divergence that whether the failure envelope is "open" or "closed" among each strength criteria in WWFEII was analyzed and discussed.This study suggests that there is no universally accurate answer,because it is connected with fiber volume fraction,mechanical properties,hydrostatic pressure and fracture angle of matrix under single compressive load.