Learning Forum

[RobinGirardon]

Hello,I'm trying to generate failures criteria on my composite structure under a buckling load (result come from eigenvalue module), but when I want to create the stress or failure plot in the Solution tab in the tree I have this error showing up : n Layered post-processing: No strain and stress data are available or its evaluation is disabled in the solution propertiesAnd when I go to the Solution properties it is impossible for me to check the Read Strains and Stresses boxe so I'm realy stuck there.nIs there any solution ? nThanks for your helpnnn

[Ashish Khemka]

nnIn Mechanical did you turn on the Stress and Strain in the Details of Output Control? Please see if it helps.nnRegards,nAshish Khemkan

[RobinGirardon]

Hi, nYes it is already turned on n

[Sean Harvey]

,nOk, so it turns out to be a documented limitation that eigenvalue buckling is not supported by ACP Post. If you wished to see failure criteria in Mechanical, you could do so and you would need to turn on stress and strain, but please keep this next point in mind. Eigenvalue buckling is meant to give you a prediction of buckling load factor and mode shapes, but not actual deformation values, stresses and strains. The eigenvector is normalized to 1.0, and the strains are derived from the deformations, and stresses derived from strain + constitutive model. So while in Mechanical you can report failure criteria for eigenvalue buckling, the value it computes for the failure criteria would be misleading. It may give you insights into the region that is critical, and maybe even the component of stress that will be critical, but the computed value of the failure criteria should not be used. See for yourself if you plot the deformed results, the max deformation in one of the x,y, or z directions will be 1.0nInstead, you should use the nonlinear buckling method. One can use the eigenvalue buckling to perturb or apply initial imperfections to the nonlinear buckling method, but that is not a requirement. I won't go into all the details of nonlinear buckling but essentially you are running a static simulation with large deflections on, seeking the maximum load before the model can not converge further. If you search in the forum for nonlinear buckling you will find other posts on this topic. Also stay tuned to our courses as we will be adding more content on buckling shortly.nThank younRegards,nSeann