How to perform a modal analysis from a nonlinear static analysis with PyAnsys?
Dear all,
I am trying to compute the eigenvalues of a mechanical system after a static analysis with "nlgeom,on" using PyAnsys.
I have run the following lines
static analysis
mapdl.run("/SOLU")
mapdl.run("antype,static")
mapdl.run("nlgeom,on")
mapdl.run("rescontrol,define,last,last")
mapdl.run("autots,on")
mapdl.run("nsub,1,10,1")
mapdl.run("time,1.")
etc outres commands
mapdl.run("solve")
mapdl.finish()
modal analysis
mapdl.solution()
mapdl.run("antype,,restart,,,perturbation")
mapdl.run("perturb,modal,,CURRENT,DZEROKEEP")
mapdl.run("solve,elform")
mapdl.run("modopt,lanb,6")
mapdl.run("solve")
mapdl.finish()
However the commands
mapdl.post1()
output = mapdl.set("LIST")
print(output)
do not give me the eigenvalues... I am wondering if the modal analysis is run properly. I note that no .Xnn files are created despite the rescontrol command line... Is the tangent matrix stiffness indeed taken into account,...
I have no clue what is wrong... I use 23R2
Best
Answers

Hello,
I think it might be helpful to review the pyMapdl example: Brake Squeal Analysis
1.6.1. Linear Nonprestressed Modal Analysis
1.6.2. Partial Nonlinear Perturbed Modal Analysis
1.6.3. Full Nonlinear Perturbed Modal AnalysisBest Regards
1 
Hi thank you for this example. I didn't see this one.
I will check it out. It seems that it works in smp computation but not dmp.
Thanks a lot !0