Abstract: This papper has processed a boundary problem of an undetermined boundary by means of elastic constraint. The greatest difficulty was an undetermined boundary condition during computing crust stress field with finite element method. We processed especially the boundary condition with method of mirror image in physics. We have transformed the distribution stress on surface of structure body into the point force of the element on boundary and then into point displacement on boundary. Through an example we proved that the method of elastic constraint is available.

摘要： 本文借助于弹性力学中的弹性约束方法,利用了物理学上的镜像法^[1],对边界条件进行了特殊处理,从而把整体结构表面上未知的分布面力转化成边界单元的节点力,解决了未知边界条件的约束问题。通过实例论证了本文提出的边界处理方法是可靠的和有效的。