Shear lag analysis of dynamically loaded smart patch/substrate structures with interface defects

本文的研究目的可以概括为以下几个方面：1.从二维偏微分方程组出发，得到了具有初始给定界面空隙位置的智能湿压电片/层结构动态时谐行为的简单耦合常微分方程组。在满足能量释放率约束条件下，研究了界面沿着出现第二模态时可能发生的界面弹性脆性分层。2.剪切滞后模型将用于将二维弹性理论简化为一维动态方程系统，用于沿界面沿着的所有三个区域的压电智能结构的轴向应力和位移。为此，将对给定的界面缺陷进行适当的建模。进一步取决于界面空隙的位置，将确定从结构的重叠区的左侧或/和右侧出现的脱粘界面长度。提出了在固定载荷、材料和几何特性下，通过相应的电梯度值来检测界面脱粘长度的可能判据。在优化分析的基础上，提出了以界面不分层为约束条件的最优结构。

The research objectives can be summarized as follows:1. To obtain the simple coupled system of ordinary differential equations for the dynamic time harmonic behaviour of a smart hygropiezothermal patch/layer structure with preliminary given location of an interface void from the 2D system of partial differential equations. The possible interface elastic brittle delamination will be studied under the satisfied restriction for energy release ratio related to the first appearance of mode II along the interface. 2. The shear lag model will be applied to reduce the 2D theory of elasticity to a 1D dynamic system of equations for the axial stresses and displacements of the piezoelectric smart structure for all three zones along the interface. For this purpose an appropriate modelling will be performed for the given interface defect. Further depending of the location of the interface void, the debond interfacial length appearing from the left or/and right sides of the overlap zone of the structure will be determined. The possible criterion for detecting the interface debond length by the respective value of the electric gradient at fixed loading, material and geometric characteristics will be proposed. On the base of the optimal analysis, the optimal structure with a restriction for an absence of interface delamination will be proposed.