含面\芯开裂损伤复合材料夹层板的自由振动

基于Zig Zag变形假定和Mindlin一阶剪切理论,提出了具有面板和芯体开裂损伤复合材料夹层板自由振动的有限元分析方法。为了更好地反映夹层板截面变形的齿形特征,分别对上、下面板和芯体建立了3个独立坐标系,并定义三部分的转角为独立变量;同时又针对面\芯开裂特征,将整个结构视为上、下子板和基板三部分。根据开裂前缘位移连续条件,建立了复合材料夹层板面\芯开裂损伤分析模型。在此变形假定和损伤模型基础上,推导了含损伤复合材料夹层板各部分的刚度阵和质量阵列式,并采用子空间迭代法求解了夹层板的固有频率。通过参数讨论得出:大面积的开裂损伤会使结构频率急剧降低;面积相同而形状不同的开裂损伤对夹层板的各阶固有频率的影响不同;适当的面板铺设方式将会提高结构的固有频率;提高面板的厚度可大幅度提高夹层板的各阶固有频率。

Free Vibration of Face\Core Debonded Composite Sandwich Plates

Based on deformation assumption and Mindlin first order shear deformation theory, a finite element method was proposed for free vibration analysis of the composite sandwich plates with debonded damage along the face/core interface. To characterize the Zig-Zag deformation of composite sandwich plates, the sub-coordinate systems for three sub-domains, such as up-face, core and low-face, are separately employed for making their rotations be independent. Considering the deformation continuous requirements along the interfacial debonding fronts, a debouding model is also established.Based on above assumption and model, the formulas of stiffness and mass matrix for the sub-domains were deduced, and sub-space iteration approach was applied to calculate the natural frequencies. From some typical examples it is concluded that large debonding size causes the sharp decrease of the natural frequencies, different debonding shape with the same size can get different natural frequencies, proper plied sequence of the faces can gain higher natural frequencies and by increasing the thickness of faces the all natural frequencies can be largely increased.