STUDIES ON THE MECHANICAL CHARACTERISTICS OF ANISOTROPIC LAMINATED COMPOSITE STRUCTURES

建立了分析层合复合材料结构固有频率、屈曲应力、屈曲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考虑了剪应力和正应力的完全影响。几组截断近似理论的控制方程已被应用于多层弹性板和梁的静力和动力问题的分析。基于连续位移分量的幂级数展开式，利用能量原理导出了二维和一维高阶理论的基本方程组。通过求解边值和特征值问题，得到了叠合板梁的连续位移分量。根据本构关系计算平面内应力分量，通过积分三维弹性连续体的平衡方程确定横向应力分量，并满足层合板上下表面的应力边界条件和层间界面的连续条件。完全满足连续条件和应力边界条件。对于多层复合材料层合板，准确地得到了层合板在厚度方向上的位移、横向剪应力和正应力的分布。目前用各种近似理论得到的结果对于一般的多层复合材料板和梁是足够精确的。数值结果与已发表的三维分层理论的结果进行了比较，在三维分层理论中，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。阐明了多层复合材料层合板中三维分层理论与单层（全局）高阶理论位移连续条件差异的影响。二维和一维全局高阶理论可以在很小的未知量范围内准确预测多层复合材料和夹层结构的位移和应力分布。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