Newsletter Artikel 29/2020

FAQ 1

Treatment of the stresses of parabolic elements from ANSYS * .rst in FEMFAT

In the ANSYS * .rst file, no node-related results (stresses, strains, ...) are saved for the middle nodes of finite elements with parabolic shape functions. So that an analysis of these middle nodes can still be carried out in FEMFAT, the results of the adjacent corner nodes are used to determine values for middle nodes.

For stresses this is done as follows:

  1. In the first step, the stress tensor at the center nodes is calculated component wise by arithmetic averaging of the stress tensor at the associated corner nodes. This is done immediately after reading the stresses in FEMFAT for each element with element node stresses. As a result, element node stresses are again obtained at the middle node, i.e. if the middle node belongs to several elements, the stress tensor differs from element to element.

  2. In the second step, FEMFAT requires node-averaged stresses for the base material calculation. These are determined either when the calculation starts (BASIC), when the VISUALIZER is started in the stress data dialog (BASIC) or when scratching (MAX, HEAT, SPECTRAL). The mean stress tensors of each element at the central node  are again arithmetically averaged component by component and the node-averaged stresses are obtained for the FEMFAT calculation:

     

    The analogous procedure applies for strains in HEAT.

    For node results, such as temperatures, the middle node values are read directly from the rst file.