Ansys Tips

As a follow up to the previous post, here's my slightly different take of the Newton-Raphson Residuals. The  help manual  shows a nice gradually decreasing stiffness curve (similar to Figure 1). It didn't match what I learned in school or Wikipedia where the algorithm was used to find the root. By rephrasing the question as finding the root for the Newton-Raphson Residual (External - Internal Force), one then gets to Figure 2. The Octave /Matlab script used to create the above plots can be found here .

When doing non-linear analysis, it is good practice to indicate you would like to save the Newton-Raphson Residuals before the analysis is started. It can go a long way in troubleshooting when/ if the solution doesn't converge later. You may do so by specifying how many youngest residuals you wish to keep. I personally like to keep 3 to see if it is consistent. Also, increase " Identify Element Violations " toggle to 1 to locate any mangled elements. Number of Residuals & Identify Distorted Elements ANSYS now spends a bit of time & resource saving the residuals as it solves each iteration (see below). If you specify only 3 (as suggested above), only the youngest 3 residuals are saved with successive overwriting of the older files. The process is highlighted in the output file below: file.out showing when residual files are saved If later ANSYS spouts out colorful language disguised as WARNING or ERROR, you would then see the following objects under...