I would like to know something about discretization error of analysis (mesh) in Femap. I found artickle (Plotting mesh discretization error in NX) where the author mensions about this in Femap, but I don't know how it works. Any hint, advice would be very welcome.
Model -> Output -> Process -> Error Estimate, and use F1 help to get a detailed description. It provides you with a measure (either absolute or relative) of the difference between element nodal results at each node. Keep in mind that stress results are usually "corner" (element nodal) results, which means that if there are four elements connected to a node, then there are 4 separate results of each element result vector (stress, strain, element force) created for that node. If the model were "perfect", all results for the same location would be identical. Because the model is a finite discrete representation, there will usually be differences ("errors") in values produced from each element. Error Estimate will produce additional results data which quantifies the size of the "error" - you will be able to view the error estimate as a contour like any other result.
Sorry for the German dialog, but this is the functionality you're looking for (Model > Output > Process). The normalized percentage is the difference between neighboring elements divided by the max value in the result vector. It should be < 10 % for a converged mesh ideally.