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Showing posts from June, 2018

Defining Ansys Superelement SUB File Manually

Photo by  James Owen  on  Unsplash A surprisingly popular blog-post written here is Exporting Stiffness Matrix from Ansys . A sensible follow up question is what can one do with the exported stiffness matrix? In a recent Xansys Forum post, a question was raised on how we can edit the stiffness matrix of a superelement and use it for our model.  An approach presented below is to first create a superelement that has the same number of DOF and nodal location that will serve as a template. An APDL script can then be written to edit the stiffness matrix entries as desired before exporting to a new superelement *.SUB file for use in future models. The self-contained script below demonstrates this.  /prep7 et ,1, 185 mp , ex, 1, 200e3 mp , prxy, 1, 0.33 w = 0.1 ! single element (note nodal locations) n , 1, w, -w, -w n , 2, w, w, -w n , 3, -w, w, -w n , 4, -w, -w, -w n , 5, w, -w, w n , 6, w, w, w n , 7, -w, w, w n , 8, -w, -w, w e , 1, 2, 3, 4, 5, 6, 7, 8 /solu antype , substr     ! analy

Non-linear Convergence

Saying a Prayer * In the few tingling seconds between saving the project and hitting Solve on Ansys, I would mutter a prayer under my breath. There is always an indescribable brief sense of helplessness and hope. Non-linear problems are tough because... they are nonlinear! A small nudge can have disproportional effects.  Learning how to solve non-linear problems takes patience and luck. Here are some resources which I found useful in my journey in learning the secret arts (in no particular order): 1. CAEAI: Best Practices ( link ) ( backup_link ) 2. Joseph Metrisin 1 : contact convergence debugging guidelines ( link ) ( backup_link ) 3. Rod Scholl: contact analysis guidelines ( link ) ( backup_link ) 4. Ansys: Could you give me tips and tricks for Non-linear simulations? ( link ) 5. John Higgins: Obtaining and Optimizing Structural Analysis Convergence ( link ) 6. PADT: Overcoming Convergence Difficulties (Part I & II ) 7. Ansys: Snap Fit Analysis - Best P

ACT to Automate Post-Processing

I gushed about the ACT console in a previous post . Here's another example of automatically populating some post processing objects for all time steps inside Mechanical after a solve.  Copy-and-paste it in Mechanical ACT Console Command Line, then hit the Enter key. Text file of script: Link . # Extracts at each time step... # x, y, z stress components, von Mises stress, max principal stress, total deformation, and x, y, z normal deformation components numsteps = ExtAPI.DataModel.Project.Model.Analyses[0].AnalysisSettings.NumberOfSteps for ct in range(numsteps): setTime = str(ct+1) + " [s]" nowTime = str(ct+1) + "s" # Normal Stresses sx=ExtAPI.DataModel.Project.Model.Analyses[0].Solution.AddNormalStress() sx.NormalOrientation =NormalOrientationType.XAxis sx.DisplayTime=Quantity(setTime) sx.Name = "Normal Stress X at "+nowTime sy=ExtAPI.DataModel.Project.Model.Analyses[0].Solution.AddNormalStress() sy.NormalOrientat