Kazutaka Kitagawa

One-dimensional shock wave interaction with rubber and low-porosity foam

One-dimensional interaction between a planar shock wave and a rubber or low-porosity foam is investigated experimentally and numerically. The considered polyurethane foam is of high density (ρc=290 kg/m3) and lowporosity (ϕ=0.76), and this corresponds to an intermediate condition between rubber and high-porosity foam. Stress-strain relations for the low-porosity foam are investigated by machine tests, which show larger deformation against compressive force and higher non-linearity in stress-strain curve as compared with rubber. Also the low-porosity foam shows a hysteresis cycle. Experiments on shock wave-foam interactions are conducted by using a shock tube. Experimental time history of the surface stress of the foam at the end of the shock tube does not show shock type stress increase, but continuous excessive stress rise can be seen, and then dumping vibration approaching to gas dynamic pressure of the reflected shock wave is followed, and the highest stress amounts about 3∼4 times of the pressure after the reflected gas dynamic shock wave. Interactive motions of gas and the low-porosity foam are analyzed using the Lagrangean coordinates system. An elastic model for a low-porosity foam is assumed to be a single elastic material with the measured stress-strain relation. Results of numerical simulations are compared with the shock tube experiments, which show essentially same stress variations with experimental results.

Attenuation properties of blast wave through porous layer

The propagation and attenuation of blast waves through porous layers is one of the important research topics related to safety assessment and prevention from explosion hazards. This study is a part of series of research on shock in complex media. Blast waves passing through porous layer such as polyurethane foam with high-porosities(≈ 98%) and low densities(≈ 28kg/m3) ; and sand layer having low-porosities(≈ 45%) and high densities (≈1500kg/m3) are tested. Peak overpressures in polyurethane foam and sand layer decrease quickly than that in air, as the blast wave is degenerated into compression waves due to its interaction with three-dimensional porosity distribution. Pressure attenuation caused in present complex media are in between 10 to 40% of the peak overpressure value in air.

Drag difference between steady and shocked gas flows passing through a porous body

Abstract. Experimental and numerical investigations of gas flows through porous materials have been carried out. We have investigated steady and unsteady processes occurring when the gas flow interacts with porous materials. Densities

Dual-Component Sensor Design for In Situ Ablation Measurement

\rho_c

An Experimental Study on Thermal Response of Low Density Carbon-Phenolic Ablators

and porosities

Visualization of Flapping Wing of the Drone Beetle

\phi_g

In-Situ Measurement of Ablation Fronts of A Low Density Ablator With An Ablation Sensor

of the four open-cell-type polyurethane foams which were investigated are

Diffusion effect of blast pressure in porous complex media

\rho_c \cong 26 \sim 56

Emission Spectra measurements in the arc heated flow of Huels type arc heater

kg/m

In Situ Ablation Measurement for an Ablative Heat Shield Using an Embedded Sensor

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