Theoretical and Experimental Studies of Failure in Anisotropic Curved Layered Structure

这项工作的主要目标是建立和雄心勃勃的 分析和实验程序来理解， 预测弯曲层状结构的破坏机理和破坏机制 复合材料.分析研究将针对（a） 确定应力的弹性分析解 一般载荷下无裂纹弯曲复合材料的响应， (b)预测初始失效模式（基体界面 破裂），基于适当失效标准的失效位置 在特定的临界载荷下，（c）确定应力 异种材料弯曲界面裂纹奇异性 圆柱正交或各向异性介质和矩阵 裂纹撞击在弯曲的界面上。有限元 研究将侧重于（a）发展奇异有限 分析裂纹尖端应力场的单元 对应于测试样本的每种失效模式， 实际尺寸。要素的制定将纳入 从分析研究中获得的适当奇异项，（B） 研究了弯曲构件破坏过程的基本特征， 复合材料，强调壳体曲率的作用，（c） 确定混合模式断裂参数K1、K11和K111 根据各种几何参数和载荷条件， (b)预测断裂模型和稳定、不稳定的裂纹扩展 或者被逮捕实验数据也将用于开发 并验证失败标准作为拟议工作的一部分。的 分析预测、有限元结果和实验结果 数据将被整理和批判性地比较，以提供一个完整的 理解弯曲复合材料的破坏行为 各种模型的预测能力 * //

The primary objective of this work is to establish and ambitious analytical and experimental program to understand and then to predict the failure mechanics and mechanisms of curved layered composites. Analytical studies will be directed towards (a) determining analytical elasticity solutions for the stress response of uncracked curved composites under general loadings, (b) predicting initial failure modes (interface of matrix cracking), failure locations based on proper failure criteria under specific critical loads, (c) determining stress singularities of curved interface crack between dissimilar cylindrically orthotopic or anisotropic media and of matrix cracking impinging on the curved interface. Finite element studies will then emphasize on (a) developing singular finite elements to investigate the stress fields near the crack tip corresponding to each failure mode for test specimens of practical dimensions. The element formulation will incorporate proper singular terms obtained from analytical study, (b) investigating the essential features of failure process in curved composites with emphasis on the role of shell curvature, (c) determining the mixed-mode fracture parameters K1, K11, and K111 in terms of various geometry parameters and loading conditions, (b) predicting fracture models and stable, unstable crack growth or crack arrest. Experimental data will be also used to develop and validate failure criteria as part of the proposed work. The analytical predictions, finite element results and experimental data will be collated and critically compared to provide a full understanding of both the failure behavior of curved composites and the predictive capability of various models.*** //