STUDIES ON THE MECHANICAL CHARACTERISTICS OF ANISOTROPIC LAMINATED COMPOSITE STRUCTURES

发展了分析复合材料层合结构固有频率、屈曲应力、位移和层间应力的整体高阶理论。在近似的二维和一维理论中，完全考虑了剪应力和正应力的影响。将截断近似理论的几组控制方程应用于多层弹性板梁的静力和动力分析。基于连续位移分量的幂级数展开，利用能量原理导出了二维和一维高阶理论的基本方程组。通过求解边值问题和特征值问题，得到了复合材料层合板和梁的连续位移分量。面内应力分量由本构关系计算，横向应力分量由平衡方程…积分确定。满足层合板顶面和底面的应力边界条件和层间界面的连续性条件。连续条件和应力边界条件完全满足。对于多层复合材料层合板，在铺层水平上精确地得到了层合板厚度方向上的位移、横向剪应力和正应力的分布。用各种近似理论得到的结果对于一般的多层复合材料层合板和梁来说是足够精确的。数值结果与已发表的三维LayerWise理论的结果进行了比较。在三维LayerWise理论中，假设面内位移和法向位移在层间界面的连续性条件下都是C^0连续的。阐明了三维层合板理论与单层(整体)高阶理论在层合板中位移连续性条件的差异对层合板的影响。二维和一维整体高阶理论可以在较少的未知量范围内准确地预测多层复合材料和夹层结构的位移和应力分布。较少

The global higher-order theories for analyzing natural frequencies, buckling stresses and displacements and interlaminar stresses of laminated composite structures have been developed. The complete effects of shear and normal stresses are taken into account within the approximate two- and one-dimensional theories. Several sets of the governing equations of truncated approximate theories have been applied to the analysis of static and dynamic problems of multilayered elastic plates and beams. Based on the power series expansions of continuous displacement components, fundamental sets of equations of two- and one-dimensional higher-order theories have been derived through the energy principles. Continuous displacement components of laminated composite plates and beams are obtained by solving the boundary value and eigenvalue problems. In-plane stress components are calculated from the constitutive relations and transverse stress components are determined by integrating the equilibrium eq … More uations of three-dimensional elastic continuum, and satisfying the stress boundary conditions on the top and bottom surfaces of laminates and continuity conditions at layer interface between layers. The continuity conditions and stress boundary conditions are satisfied completely. For multilayered composite laminates, the distribution of displace-ments and transverse shear and normal stresses in the thickness direction has been obtained accurately in the ply level.The present results obtained by various sets of approximate theories are considered to be accurate enough for general laminated composite plates and beams with many layers. Numerical results are compared with those of the published three-dimensional layerwise theory in which both in-plane and normal displacements are assumed to be C^0 continuous in the continuity conditions at the interface between layers. Effects of the difference of displacement continuity conditions between the three-dimensional layerwise theory and the single-layer (global) higher-order theory are clarified in multilayered composite laminates. The two- and one-dimensional global higher-order theories can predict displaceme nt and stress distributions of multilayered composite and sandwich structures accurately within small number of unknowns. Less