Discussion Forum

Hi everyone,

I am doing a uniaxial compression test on lattice strucutre. A prescribed displacement is done on the topmost surface and the bottom surface is kept fixed. The study is being done on structural mechanics with a stationary analysis and an auxilary sweep was performed by varying the prescribed dispalcement. The model was given a material property of linear elastic material with plasticity as sub option. I chose the yield function as von mises stress and isotropic hardening model was set at voce. The material i wanted to model was stainless steel 316L and all the material values were assigned following the engineering tool box. I am trying to generate a stress strain curve using this analysis. Eventhough i can visualise the deformation process of the lattice, once the lattice has been compressed to its maximum position, the stress strain curve is still being shown in the plastic region. Normally the curve should move upwards (i have attached a sample graphs of how the stress strain curve of compressed lattice looks like) once it is compressed at max. I generated the graph by looking at the reaction force (RFz) on the topmost surface and the corresponding displacement. Any idea why COMSOL is not generating the required plot? is it because of the material modes that i have defined or is it because i am analysing the stress-strain component in a wrong manner?

The lattice once deformed completely moves beyond the fixed constraint upon further deformation. could this be a another reason for this?