Dynamic response of foam-filled multi-tube beams subjected to transverse low-velocity impact: Theoretical and numerical studies

Abstract

The large-deflection behavior of foam-filled multi-tube beams subjected to transverse low-velocity impact is investigated using theoretical analysis and numerical simulations. A yield criterion for large-deflection plastic deformation is proposed, and analytical models based on upper-bound, lower-bound, and membrane theories are developed to predict the impact response while accounting for the coupling between bending and axial forces. The theoretical predictions are validated through finite element simulations, with numerical results consistently lying within the theoretical bounds. The numerical results demonstrate that, under the same impact conditions, the foam-filled multi-tube configuration exhibits superior deformation resistance and enhanced energy absorption capacity compared with foam-filled single-tube and hollow tube beams. Parametric studies based on the theoretical model further indicate that, under conditions of constant mass per unit length, increasing the yield strength ratio of the foam and the tube or reducing the thickness of the inner and the outer tubes effectively reduces plastic deformation and improves load-bearing and energy absorption capacity, whereas an excessive aspect ratio of beam or a low inner-to-outer tube thickness ratio degrades impact resistance. These findings provide valuable theoretical insights and practical guidance for the design and optimization of foam-filled multi-tube configurations for energy absorption and impact protection applications.