Viscous energy dissipation as an additional energy absorption mechanism for blast resistanc

This study examined energy absorption methods to protect against a blast load. Blast resistant panels designed to resist blasts and high-velocity impacts usually dissipate most of the delivered energy through inelastic deformation of solids. A concept is explored to improve the energy absorption of such structures by the addition of a viscous mechanism of energy dissipation. The viscous dissipation mechanism relies on the fact that when a viscous liquid is forced through narrow passages at high speeds, it undergoes high shear rates that cause energy dissipation. Proof-of-concept studies were conducted to assess the efficacy of this methodology. A simple test specimen in the form of a steel tube with capillaries attached at both ends was chosen for both analytical and experimental study. Both empty and liquid-filled test specimens were subjected to experimental and simulated drop-weight impact tests. These test specimens were also subjected to simulated blast load tests. Fluid structure interaction analyses in the form of Coupled-Eulerian-Lagrangian simulations were performed to assess the energy dissipated both by solid plastic deformation and liquid viscous dissipation in the drop-weight and blast simulations. The liquid flow speed generated by the applied impacts and blast loads was found to be a critical factor in determining the contribution of the viscous mechanism. The moderate liquid flow speeds generated by the drop-weight impacts resulted in negligible viscous energy dissipation. The simulated blast loads generated much higher liquid flow speeds and as a result the viscous energy contribution to the total absorbed energy in the test specimens approached 30%. The viscosity of the liquid has a major effect on the fraction of energy absorbed in the form of viscous dissipation. Results of this study support the viability of the concept of viscous-assist for improving the ability of protective panels and structures to withstand high-speed impact and blast loads.