Stress Analysis

Abstract

A stress analysis of bidimensional bodies can be done utilizing a standard finite difference program like IBM Strudl (Structural Design Language). The discretization process is very long, tedious and error prone as for every triangle the vertices must be numbered according certain rules, their coordinates measured and punched on cards and the incidences with neighboring vertices listed, and there could be some hundreds or even thousand of triangles. By using TEADI to describe the body and the special program illustrated by Fig. 31-33, this process can be automatized and carried on with the control of the operator, who only chooses the grid size, shape and boundaries. The choice of the density of triangles and the proportion of their sides is left to the operator skill. The result is a deck of cards that can be used directly as input deck to the STRUDL program. Other difficulties are faced by the designers when they receive the output of the STRUDL job, as this consists in a long list of the principal stresses and their direction in the center of every triangle. This means so many numbers that it is very difficult to have a synthetic feeling of the situation. For this reason a second program is beeing prepared which gives a graphical picture of the situation visualizing the body and two vectors for any triangle scaled and directed as the principal stresses, the isostatic and the curves of the points having the same δ ideal to give an idea of the more critical zones.