论文部分内容阅读
1.引言复杂结构的有限元计算,一般都需采用“多元高次模式”,即按结构实际情形作一般三维元、壳元(厚壳及薄壳)以及平面元乃至杆件元等混合单元剖分;而且为了拟合复杂曲面部位,需采用任意曲面的高次等参元.这时,一个重要问题是如何保证不同类型单元相互连接时的几何相容性与位移相容性.在不同文献中,单元交接处理的方法不尽相同,通常需视实际情况作特殊的处理,例如设置过渡单元、在单元级运算中消去与相邻单元不一致的自由度、在尺度变化激烈的部位“以厚就薄”作细密剖分等等.我们在实际应用中也作了多种尝试,但感到各种处理方案不够统一简捷,且仍有若干情形难以对付,如:1)在台阶形或丁字型、工字型部位,势必出现相邻单元交接面上结点个数、位置乃至自由度类型或个数互不相同的情形,
1. Introduction Finite element calculations of complex structures generally require the use of “multiple higher order modes”, ie, general three-dimensional elements, shell elements (thick shells and thin shells), and planar elements and even rod elements and other mixed elements according to the actual structure. In order to fit complex curved surface parts, high-order isoparametric elements of arbitrary surfaces need to be used. In this case, an important issue is how to ensure the compatibility of geometric compatibility and displacement when different types of elements are connected to each other. In the literature, the method of unit handover processing is not the same. Usually, special processing is required depending on the actual situation. For example, the transition unit is set, the degree of freedom that is inconsistent with the adjacent unit is eliminated in the unit-level operation, and the position where the scale changes is fierce. “Thickness is thin” for fine breakdown etc. We have also made many attempts in practical applications, but we feel that various treatment solutions are not uniform and simple, and there are still some cases that are difficult to deal with, such as: 1) in the step-shaped or T-shaped Types and I-shaped parts are bound to have different numbers of nodes, positions, and degrees of freedom, or different numbers of degrees of freedom.