复合材料MMB试件Ⅰ-Ⅱ混合型层间裂纹扩展分析  

Analysis onⅠ-Ⅱmixed interlaminar crack propagation of composite MMB specimens

作　　者：邓健[1,2] 卢天健 尹乔之[1,3] DENG Jian;LU Tianjian;YIN Qiaozhi(State Key Laboratory of Mechanics and Control of Mechanical Structures,Nanjing University of Aeronautics and Astronautics,Nanjing 210016,China;MⅡT Key Laboratory of Multifunctional Lightweight Materials and Structures,Nanjing University of Aeronautics and Astronautics,Nanjing 210016,China;Key Laboratory of Fundamental Science for National Defense-Advanced Design Technology of Flight Vehicle,Nanjing University of Aeronautics and Astronautics,Nanjing 210016,China)

机构地区：[1]南京航空航天大学机械结构力学及控制国家重点实验室,南京210016 [2]南京航空航天大学多功能轻量化材料与结构工业和信息化部重点实验室,南京210016 [3]南京航空航天大学飞行器先进设计技术国防重点学科实验室,南京210016

出　　处：《航空学报》2021年第2期144-155,共12页Acta Aeronautica et Astronautica Sinica

基　　金：国家自然科学基金(51905264,11972185);中国博士后科学基金(2019M661818,2019M650115);江苏高校优势学科建设工程资助项目;中央高校基本科研业务费专项资金(NP2017401)。

摘　　要：基于经典层合板理论及双线性黏聚区本构关系,建立了含一般分层裂纹层合板的理论模型,对Ⅰ-Ⅱ混合型弯曲(MMB)断裂试件进行了裂纹扩展理论分析。提出了一种Ⅰ-Ⅱ混合型断裂叠加模型,引入Ⅰ型裂纹分量的刚体转动位移,同时考虑了裂纹长度超过试件半长后中部载荷分量对裂纹扩展的闭合效应,并根据黏聚区力学响应,分段获得了位移函数通解。结合叠加模型的边界条件与连续性条件,分析了MMB试件的裂纹扩展过程,求解获得了载荷-位移曲线。通过与梁模型预测以及试验结果进行对比,验证了本文模型对Ⅰ-Ⅱ混合型裂纹扩展预测的有效性和准确性,并讨论了初始断裂模式混合比及闭合效应对裂纹扩展过程的影响。结果表明:初始Ⅱ型裂纹比重较大时,中部载荷的闭合效应更为明显,可能出现Ⅰ型裂纹完全闭合的情况;裂纹扩展过程中,当裂纹长度小于试件半长时,断裂混合比基本保持常数;当裂纹扩展超过试件半长后,闭合效应明显,混合裂纹形式逐渐向单一型断裂模式退化。A theoretical model of general delamination cracked laminates is established based on the classical laminate theory and the bilinear cohesive zone model.The crack propagation in Mixed-Mode Bending(MMB)specimen is studied considering both I andⅡmode cracks.A crack superposition model ofⅠandⅡmode cracks is proposed,followed by the introduction of the rigid body rotational displacement of the modeⅠcrack component.The closing effect of the central load component on the modeⅠcrack propagation is also considered in the MMB tests.According to the mechanical responses in the cohesive zone,apiecewise general solution to the displacement functions is obtained considering that the crack could be larger than half of the specimen length.Combining the boundary and continuity conditions of the superposition model,we analyzes the crack propagation process in the MMB test,obtaining the load-displacement curves.Comparison with both predictions of the beam model and the existing test results verifies the effectiveness and accuracy of the proposed model forⅠ-Ⅱmixed mode crack propagation.The model is further applied to the discussion of the effect of mode mixity ratios and the closing effect.The results show that the closing effect is more intensive when the initial mixity of the modeⅡcrack is relatively larger,which can lead to the closure of the mode I crack.During crack propagation,the mode mixity ratio remains essentially constant when the crack length is smaller than half of the specimen length.Conversely,as the crack length exceeds half of the specimen length,the crack mode gradually degenerates to a single mode fracture with a relatively large initial mode mixity ratio due to the closing effect.

关 键 词：MMB试验 分层 黏聚区 混合比 裂纹叠加 

分 类 号：V258[一般工业技术—材料科学与工程] TB332[航空宇航科学与技术—航空宇航制造工程]