A Microcomputer-aided Three-dimensional Finite Element Method. A Double-tandem-type Substructuring Method as an Efficient Calculation Method.

Abstract

This paper presents a double-tandem-type substructuring method as an efficient calculation method of a microcomputer/personal computer-aided finite element method (FEM). This method uses the intermediate substructures between both basic and final ones in order to decrease the time for composition of stiffness submatrices in the tandem-type substructuring method. This method needs to utilize the disk memory storage unit such as floppy and hard disks in order to store the data of the stiffness submatrices and/or their decomposed ones. The stiffness submatrices of the storage unit are divided from a structure stiffness matrix within the limit of the machine memory capacity to be used. The data of the LDU submatrices are placed in the data set of the stiffness submatrices in order to save storage space in the unit. The FEM using the method is applied to an analysis of a three-dimensional elastic block with semicylindrical notches under tension. Therefore, the FEM is applicable for analysis of structures of a large-size matrix required for a memory capacity larger than that of the machine itself. This method also contributes to the decrease in memory capacity and central processing unit time in the conventional FEM.