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

主要研究内容如下：1.从二维偏微分方程组出发，初步确定界面孔洞的位置，得到智能湿压电贴片/层结构动态时间谐和行为的简单耦合常微分方程组。在满足与界面上第一次出现II型相对应的能量释放率的约束条件下，研究了界面可能发生的弹性脆性分层。2.采用剪滞模型，将二维弹性理论简化为一维动态方程组，得到了界面上所有三个区域的压电式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。此外，根据界面空洞的位置，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。提出了用固定载荷、材料特性和几何特性下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，提出了具有界面无分层约束的最优结构。

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.