Numerical modelling of laterally impacted plates reinforced by free and end connected stiffeners

Experimental drop weight impact tests have been performed to examine the dynamic response of small-scale stiffened plates struck laterally by a mass with a spherical indenter. The laboratory results are compared with numerical simulations. The specimens are supported at two opposite edges and impacted at different locations along the span. In the unsupported edges, the ends of the stiffeners are either connected to transverse stiffeners or remain free. The impact scenarios could represent incidents in marine structures, such as load actions due to dropped objects on decks. The experiments are conducted using a fully instrumented impact testing machine. The obtained force–displacement responses show a good agreement with the simulations performed by the LS-DYNA finite element solver. The finite element model includes defining the experimental boundary condition so as to simulate small axial displacements of the specimen at the supports. This representation can be used to analyse the structural impact response of similar small-scale engineering structures. The strain hardening of the material is defined using experimental data of quasi-static tension tests and the strain rate sensitivity is evaluated using standard coefficients of the Cowper–Symonds constitutive model. The results show that the plastic response of the specimens is highly sensitive to the amount of restraint provided at the supports, particularly for the specimens with ends of the stiffeners free since they experience larger lateral deflections and, consequently, larger axial displacements at the supports. Furthermore, the contribution of the stiffeners to the impact response of the specimens is assessed through numerical simulations of unstiffened plates.