给出了预测六边形蜂窝材料等效剪切模量及其尺寸效应的圆筒扭转力学模型和扭转能量法,建立了等效面外剪切模量G13相对于材料体分比v、周向单胞数n、圆筒半径r和单胞层数参数m变化的解析表达式;同时将扭转能量法、有限元数值模拟计算和G-A经典细观力学方法进行了比较,从理论上揭示并验证了尺寸效应的存在性.结果表明,当蜂窝体胞尺寸相对结构尺寸无穷小时,预测结果趋近于细观力学方法的结果.此外,利用周期性蜂窝材料的结构对称特性,使用体胞子结构有限元计算模型进行等效面外剪切模量及其尺寸效应的预测,在不影响计算结果的前提下极大地提高了计算效率.
In this paper, a cylinder torsion model and a torsion energy method are proposed to predict equivalent out- plane shear modulus of hexagon cellular materials. An analytical expression for its size effect is constructed in terms of volume fraction(v), number of cells in circumference(n), radius of the hollow cylinder(r) and number parameter of cell layers(m). Comparisons are made among the results of torsion energy method, finite element numerical simulation and G-A microstructure mechanical method. The size effect is revealed and proved theoretically. Numerical results show that when the cell size trends to be infinitely small with regard to the size of the structure, predicted results approach those obtained by mesoscopic mechanics method. Due to the cyclic symmetry of periodic cellular materials, it is shown that the computing efficiency can be greatly increased by means of the substructure model.