有限单元分析中的移动边界方法

本文就波动问题提出一种移动边界的有限单元解法。此时模型边界的位置不是固定的,它将随着波前向前推进和退回,以保证在计算时间长度内边界反射波不到达观测点。文中给出了计算边界有效载荷的递推公式,可以简便有效地避免虚假反射波的干扰。为降低运算量和虚模型中的存贮,应适当选取移动间隔,截断误差和移动起点。对于层状模型,若采用直接积分的中心差分方法,计算过程十分简单,也可用于有限差分等方法的计算中。该方法在应用上的限制是对计算机内存量的要求较通常方法为大。

PROPAGATING ENCLOSURE METHOD IN FINITE ELEMENT ANALYSIS

The propagating enclosure method is proposed in dynamic analysis using the finite element method. In this technique the position of the artificial boundary enclosing the computational model is not fixed but propagates forward and backward along with the wave front, in order to prevent the contamination of the solutions from spurious reflected waves. The method is simple and efficient. A recursion formula to calculate the effective load at the boundary is presented. The appropriate selections of the moving interval, truncation error and the point of onset is to minimize the computer storage and the number of operations required. For a layered model the computational procedure for the central difference method of direct integration is very simple and easy. This method is applicable in direct integration schemes and finite difference analysis. The limitation of the method is that it requires a larger computer storage.