nThanks for your conmment! In reality, I'm doing the test of hydrostatic pressure for the mode, which is surrounded with water. I want to get the similar result to the experiment in the simulation by ansys. From the egenvalue buckling,I can get the geometry fit to the experiment result. But in nonlinear analysis, when I set the load pressure a little higher than the egenvalue buckling ctrtical load ,I find the equivalent stress so much higher than the limit stress, which shows the yield or even fracture appear for a long time. nSo could you please give me some help to solve the problem?nThe following is the page aftrer the experiment and the critical load in test is 32-36MPa.nRegardsnTaonn