考虑多尺度界面力学特性的损伤复合材料层合板分岔屈曲性能的等代化

An equivalent model on bifurcation buckling of delaminated composite laminates with multiscale interfacial behaviors

提出了一种等效理论来分析含损伤碳纤维增强树脂T300/QY8911复合材料层合板的分层屈曲。针对含贯穿脱层层合板产生面外弯曲后的受力特点,引入损伤界面的接触效应,根据精确模型所给出的多尺度变形失效机制,提出了一个基于刚度等效理论来分析损伤层合板结构失效的力学性能。通过将含脱层的区域等效成一个几何形状和铺设方式完全一致,但刚度相应折减的完善子板,运用三分区模型,根据板壳理论、复合材料力学等基本原理建立各子板的屈曲控制方程,同时结合边界条件和连续性条件求解。算例分析表明,本文所得的屈曲荷载与考虑接触效应精确模型所得的解析解及ABAQUS有限元结果高度吻合。该研究方法充分考虑了脱层带来的刚度降低以及由于分层界面处非线性抗穿透约束的影响,不仅大大简化了繁琐的推导过程和节省了计算量,而且揭示了深层次的力学机制,更为主要的是,该方法可以有效推广到含多分层损伤层合板的非线性力学性能的评估,为航空航天先进复合材料的结构设计和力学分析提供有力的技术支持。

This paper presents a substitution model based on stiffness equivalence to study the delamination buckling in T300/QY8911 carbon fiber reinforced polymer composite,delaminated laminates.The delaminated laminate contains a buried through-width delamination.Exact model was introduced in which the nonlinear contact effect between sub-laminates above and beneath the delamination was included.It is found from exact analysis that the sublaminates above and beneath the delamination undergo identical global deflection.Based on such observation an equivalent substitution model which is perfect is proposed to replace the delaminated portion of the laminate.The substitute model has the same geometric size and is stacked in the same sequence as that of the delaminated portion.Further observation of the deflection modes also suggests that the stiffness of the substitute model is taken as the sum of the stiffness of the two portions above and beneath the delamination.Using the equivalent substitution model the delaminated laminate is divided into three sub-laminates,each of which is delamination-free.Governing equations for the buckling of the delaminated laminate were established and were solved by considering the boundary conditions at the ends and the continuity conditions at the delamination fronts.Analytical solutions of the buckling load are obtained for different delamination size and depth.The efficiency and accuracy of the presented model was confirmed by comparing with the exact results and ABAQUS predictions,both showing agood agreement with those from presented model.The model presented herein greatly simplifies the tedious derivation and saves the calculations,thus is in favor of engineers to conveniently and effectively estimate the degradation of the mechanical performances caused by the delamination.More importantly,the deep mechanical mechanism can be effectively extended to evaluate the nonlinear mechanical properties of laminates containing multiple delamination yet providing apowerful technical support for structural design and mechanics analysis of advanced composites.