Finite element modeling of crushing of CFRP cylindrical tubes under low-velocity axial impact

The dynamic axial crushing response of cylindrical tubes made of unidirectional (UD) carbon fiber-epoxy material is investigated numerically with emphasis on generating realistic crushing modes and crushing morphologies besides predicting crushing force with good accuracy. The emphasis is on the crushing modes since only the strong similarity between predicted crushed modes by the FE model and experimental observations can assure that the FE model dissipates the energy in the same manner that real composite absorbers dissipate it during the experimental trial. The impact behavior of two multi-layer models of laminated cylindrical tubes having different stacking sequences, namely cross-ply and angle-ply, were simulated using stacked layers of conventional 2D shell elements (S4R) bonded with the cohesive element interface model in ABAQUS. The FE progressive failure model of UD composite layers, including the damage initiations, damage evolution law, and element removal, is executed through a user-defined material subroutine (VUMAT) in ABAQUS/Explicit code. The implemented progressive failure material model represented well the various crushing modes, including fragmentation mode, splaying mode, and axial splitting of UD lamina in the splaying crushing mode. The FE model was validated by experimental test results obtained by the authors for cross-ply and angle-ply tubes subjected to axial impact.

Automated summary

This research numerically investigated the dynamic axial crushing response of cylindrical tubes made of unidirectional carbon fiber-epoxy material, focusing on generating realistic crushing modes and morphologies, as well as accurately predicting crushing force. Experimental validation was conducted to verify the accuracy and reliability of the FE model.