Experimental Measurement and Analysis of Stress/Shock Wave Propagation Speed through Pre-strained Silicone Foam Pads under Lateral Confinement

Song, Bo; Sanborn, Brett; Lu, Wei‐Yang

doi:10.1007/s40870-019-00196-w

Cited by 5 publications

(2 citation statements)

References 45 publications

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“…microfluidics [20], aerodynamics and aero acoustics [21,22]. In fields such as aerospace, military, and transportation to mitigate blast or shock impact, foam materials are placed in the lateral direction [23][24][25][26]. Surface cleaning based on the laser-induced shock wave generation can remove small particles from solid surfaces finds a good application in semiconductor industry for decontamination of the surface of the material [27,28].…”

Section: Introductionmentioning

confidence: 99%

Dynamics of spatially confined ns laser induced atmospheric air plasma and shock waves: visualization vis-à-vis validation

Guthikonda

Manikanta

et al. 2023

J. Phys. D: Appl. Phys.

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A clear visualization of the physical processes of spatially confined ns laser induced atmospheric air plasma within a rectangular glass cavity using optical imaging is presented. The occurrence of various processes starting from the early plasma and shock wave expansion dynamics to shock reflection at the cavity boundaries and compression of the plasma due to reflected shockwaves is studied using defocused shadowgraphy and self-emission imaging techniques. Experimentally, we evidenced that the counter propagating reflected primary shockwaves (PSW) interact with the expanding plasma generating a secondary shockwave (SSW) which compresses the plasma core, modifying the plasma morphology resulting in enhanced plasma parameters. The numerical simulations performed via the two-dimensional hydrodynamic (2D-HD) FLASH codes, revealed that the number density increases up to a maximum of 3.6 times compared to the unconfined plasma. The input laser pulse energy and the aspect ratio of the cavity is observed to play a dominant role in the confinement and compression of the plasma.

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Section: Introductionmentioning

confidence: 99%

Dynamics of spatially confined ns laser induced atmospheric air plasma and shock waves: visualization vis-à-vis validation

Guthikonda

Manikanta

et al. 2023

J. Phys. D: Appl. Phys.

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“…In contrast to the gasgun direct-impact configuration of the afore cited studies, our setup allows measurement of the force on the impact side of the specimen. Further relevant studies include [15][16][17].…”

Section: Introductionmentioning

confidence: 99%

The Symmpact: A Direct-Impact Hopkinson Bar Setup Suitable for Investigating Dynamic Equilibrium in Low-Impedance Materials

et al. 2021

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Background Measuring the dynamic behavior of low-impedance materials such as foams is challenging. Their low acoustic impedance means that sensitive force measurement is required. The porous structure of foams also gives rise to dynamic compaction waves, which can result in unusual behavior, in particular if the foam material is so thick, that dynamic force equilibrium is not reached. Objective This work investigates comparatively large polyurethane foam specimens with densities in the range of 80 – 240 kg/m3 to deliberately achieve a state away from force equilibrium during high-rate compaction. The aim is to understand how an increase in strain rate leads to a reduction in strength for such materials. Methods A specialized direct-impact Hopkinson bar is employed. It uses polycarbonate bars to achieve the required long pulse duration of 2.6 ms to compress the large specimens into the densification regime. In contrast to existing setups, both striker and output bar are instrumented with strain gauges to monitor force equilibrium. The absence of an input bar allows monitoring force equilibrium more accurately. Special attention is paid to the calibration of strain gauges, taking non-linear effects, wave dispersion and attenuation into account. Digital Image Correlation is employed to analyze elastic and plastic compaction waves by means of Lagrange diagrams. Results Depending on density, the specimens show saturation of dynamic strength increase at high rates of strain $$\approx$$ ≈ 500 /s, or even negative strain rate sensitivity in case of the lowest density. The occurrence of apparent negative strain rate sensitivity is accompanied by a localized structural collapse front, moving at a low velocity of $$\approx$$ ≈ 10 m/s through the material. This apparent strain rate sensitivity is a structural effect which is related to the thickness of the specimen. Conclusions The primary aim of material characterization using Hopkinson bars is to achieve a state of force equilibrium. For this reason, very thin specimens are usually employed. However, data gathered in this way is not representative for thick foam layers. Here, an increase of strain rate can lead to a decrease of strength if homogeneous deformation is replaced by a dynamic compaction wave. This behavior can occur at strain rates encountered under conditions such as automotive crash.

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Characterization of dynamic confinement response of potting materials at different strain rates and temperatures

Song,

Sanborn,

Loeffler

et al. 2023

Mechanics of Materials

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Experimental Measurement and Analysis of Stress/Shock Wave Propagation Speed through Pre-strained Silicone Foam Pads under Lateral Confinement

Cited by 5 publications

References 45 publications

Dynamics of spatially confined ns laser induced atmospheric air plasma and shock waves: visualization vis-à-vis validation

Dynamics of spatially confined ns laser induced atmospheric air plasma and shock waves: visualization vis-à-vis validation

The Symmpact: A Direct-Impact Hopkinson Bar Setup Suitable for Investigating Dynamic Equilibrium in Low-Impedance Materials

Characterization of dynamic confinement response of potting materials at different strain rates and temperatures

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