Learning Forum

[Govindan Nagappan]

Accuracy of result: Stresses and strains are calculated at the integration points, and for higher-order elements, we always use reduced integration to alleviate volumetric locking, so we have 2x2 integration points . This means that the midside node stresses are always average of the corners. So, Mechanical and APDL postprocessors calculate the midside nodes as the average of the corners on-the-fly to plot it. There is no approximation and the actual calculated results are plotted.nEfficiency: Because the midside node stresses end up being the average of the corner node stresses, to reduce disk space, we don't keep stresses at the midside nodes in the result filenOutput of stresses at midside nodes: You will have to use command objects to export the midside node result data in Mechanical. You can use PowerGraphics (/GRAPHICS,POWER) and turn on 2 element faces (/EFACET,2), which is valid for higher-order elements, you can list the midside node stresses with PRNSOL. This could be redirected to a file with /OUTPUT to be retrieved. Please note that this only works for averaged results, or nodal solution (PRNSOL), not unaveraged results, or element solution (PRESOL), since the latter just directly accesses the data from the .rst file.nn

[Dragana Jandric]

/EFACET controls the fineness of the subgrid that is used for element plots. The element is subdivided into smaller portions called facets. Facets are piecewise linear surface approximations of the actual element face. In their most general form, facets are warped planes in 3-D space. A greater number of facets will result in a smoother representation of the element surface for element plots. /EFACET may affect results averaging. nFor midside node elements, use NUM = 2; if NUM = 1, no midside node information is output.n