FEM numerical strategies for the evaluation of the accumulated plastic strain due to a cyclic load condition

In this study, the phenomenon of accumulation of residual plastic deformation is numerically evaluated for a stiffened panel subjected to uniaxial cyclic loading. In particular, three strategies are investigated through the use of FEM (Finite Element Method) in the ADINA Software environment. The models presented are characterized by the same geometrical characteristics, but differ in the numerical parameters, i.e. mesh density and element type. Namely, a full shell-element model, a full 3D-solid-element model, and a combine shell-solid elements model are investigated. The output of the analyses carried out on the three models are the assessment of the accumulated plastic strain recorded in the unloaded phase of the cyclic analysis and the effect of these residual plastic deformations on the ultimate strength capacity of the structure. Finally, the results of the three models are compared in order to understand which one could be more suitable and reliable for the evaluation of this phenomena, i.e. the arise of plastic residuals and the reduction of the load bearing capacity of the panel.