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The resistance to flow of imbibed fluids in soft porous structures subjected to compression can be a solution for impact attenuation. The mechanism, named ex-poro-hydrodynamic (XPHD) lubrication, is based on permeability variation with porosity, which, at its turn, depends on the compression degree of the porous structure. A literature survey revealed scarce information regarding the permeability of compressed reticulated foams or 3D fiber-based structures, used in XPHD applications. Moreover, the permeability depends on the fluid and its velocity. This paper presents experimental data of the permeability of glycerine for an in-plane, axisymmetric flow through a porous material subjected to various degrees of compression. The experiments were done on an in-house made radial permeameter with pressure differentials up to 6 bars. The experimental data was compared with the predicted results, using the well-known Kozeny-Carman equation and related formulations.

Based on the analysis of existing collective shockwave protection methods worldwide, this paper addresses the mitigation of shock waves by means of passive methods, namely the use of perforated plates. Employing specialized software for numerical analysis, such as ANSYS-AUTODYN 2022R1®, the interaction of shock waves with a protection structure has been studied. By using this cost-free approach, several configurations with different opening ratios were investigated, pointing out the peculiarities of the real phenomenon. The FEM-based numerical model was calibrated by employing live explosive tests. The experimental assessments were performed for two configurations, with and without a perforated plate. The numerical results were expressed in terms of force acting on an armor plate placed behind a perforated plate at a relevant distance for ballistic protection in engineering applications. By investigating the force/impulse acting on a witness plate instead of the pressure measured at a single point, a realistic scenario can be considered. For the total impulse attenuation factor, the numerical results suggest a power law dependence, with the opening ratio as a variable.

-This paper presents the experimental determination of permeability for unidirectional in-plane flow through a thin layer of nonwoven porous textile subjected to various rates of compression. The experiments were made on an original device that allows the variation of porous layer compression and pressure differential. The permeability was calculated assuming the validity of Darcy law and, in parallel, Darcy-Forchheimer model. The preliminary results obtained with water show that pressure gradient does not influence sensibly the resistance to flow of the material and Darcy's law is applicable. For permeabilityporosity correlation the experimental results were fitted using the well-known Kozeny-Carman equation. Also good correlation was found with other two models derived from Kozeny-Carman.