Energy absorption investigation of SFRFC-filled double circular tubes under quasi-static compression and low velocity impact loading

The filled thin-walled tube (FTT) is a common energy absorption device, which consists of two important parts: filled materials and thin-walled tubes. According to existing researches, the filled materials significantly influence the mechanical properties of FTTs, especially the energy absorption capacity. In this study, a novel design of FTTs is proposed and studied, which adopts the double aluminum (Al) pipe and is filled with the steel fiber reinforced foamed concrete (SFRFC). Firstly, specimens with different steel fiber contents of 0, 0.5, 1, 1.5, and 2% are prepared and tested under quasi-static compression, and the influence of dynamic velocity (4.4, 6.2and 7.6 m/s) are investigated; then, the numerical modeling is conducted to study the influence of structural parameters on the energy absorption properties of the proposed SFRFC FTTs under quasi-static compression loadings. Results show that an appropriate content of steel fiber can prolong the stress platform under quasi-static compression loadings, and stabilize the fluctuation during dynamic plastic buckling. The thickness、diameter、aspect ratio of SFRFC FTTS have a significant effect on the SEA and CFE, especially the thickness of the inner tubes, which means the geometry parameters obviously affect the crashworthiness characteristics of SFRFC FTTs. According to the results of this research, it can be concluded that SFRFC is an excellent and potential energy adsorption filled material for FTTs, which can obviously improve the mechanical properties of filled thin-walled tubes under quasi-static and low velocity impact loadings.