Crushing responses and energy absorption characteristics of the dynamic stiffening porous material subjected to different strain rates

Porous material (PM) has excellent energy absorption performance and is widely used as an impact-energy absorber. However, the PM may provide little utility when the impact conditions change. Shear stiffening gel (SSG) with an extremely strong viscosity effect can be as a dynamic responding fortifier to overcome the limitation of PMs. In this paper, a rate-dependent, smart energy-absorbing material (SSG/PM) is fabricated by incorporating SSG that is reinforced with CaCO₃ particles onto the PM. Aided by the dynamic compression experiments at the strain rate range of 0.001 to 100 s⁻¹, both SSG/PM and neat PM are assessed and compared for crushing performance. Results reveal that the SSG/PM exhibits a pronounced dynamic stiffening characteristic in response to various strain rates owing to the rate-dependent phase transition of embedded SSG, thereby contributing to enhancing the PM skeleton's ability to withstand deformation. The SSG/PM displays a noteworthy boost in energy absorption (up to 831.98 %). Moreover, the influence of loading rate, particle mass fraction, and PM aperture size are also examined. The findings indicate that its crushing resistance and energy absorption capability are enhanced with the increase in strain rate, demonstrating the ability to adapt to various dynamic scenarios. The use of a higher particle mass fraction and smaller aperture size helps to improve the energy absorption capability of the SSG/PM. Additionally, quantitative energy analysis is implemented in which the energy dissipation mechanisms of the SSG/PM are attributed to the synergistic interaction of skeleton deformation, shear stiffening effects, and particle enhancement. It is ascertained that as the loading rate increases, the shear stiffening effect continues to strengthen; the particle content effect exhibits a rising-falling trend; while the skeleton deformation shows a rate-independent feature. This study sheds light on the crushing behaviors and corresponding energy dissipation mechanisms of SSG-based composites, thereby providing valuable insights for the design of SSG-based composites.