Comparison of Energy Absorption Performance and Mechanical Response of Metal Fiber Porous Materials under Two Strain Rates

The relationship between dynamic impact response and pore structure of metal fiber porous materials is a frontier interdisciplinary science issue in the fields of materials and mechanics. Dynamic impact (strain rate of 800 s⁻¹) and quasi-static compressive (strain rate of 10⁻³ s⁻¹) behavior of stainless steel fiber porous materials (SSFPMs) are discussed and compared for different porosity levels and fiber diameters. Furthermore, the stress wave character during dynamic compression is also analyzed. Results indicate that the compressive properties and the plateau region of the stress–strain curve are affected significantly by porosity and strain rate; high strain rate or low porosity yields higher compressive strength, higher Young's modulus, and shorter plateau region. Moreover, SSFPMs with a porosity of 70% or less may be especially suitable for applying at the quasi-static compression condition to absorb energy completely. Besides, the optimum porosity or the allowable peak stress at a certain condition can be determined according to the energy absorption diagram of SSFPMs. Additionally, the stress wave propagated inside SSFPMs comprises three waves, the incident, the reflected, and the transmitted ones, independent of porosity and fiber diameter, and the propagation behavior of the stress wave is mainly influenced by porosity, not fiber diameter.