Shock wave

About: Shock wave is a research topic. Over the lifetime, 36184 publications have been published within this topic receiving 635848 citations. The topic is also known as: Shock waves & shockwave.

Optical technique for determining rarefaction wave velocities at very high pressures

Abstract: An optical technique to determine rarefaction wave velocities is described. The technique utilizes the property that many transparent materials emit copious radiation when shocked to high pressures. The usual method of producing a rarefaction wave by impacting a target plate with a thinner rapidly moving driver plate is employed. The target plate is made in the form of a step wedge which is covered by the transparent material (or analyzer). When the shock reaches the analyzer it radiates steadily until the rarefaction from the backside of the driver plate overtakes the shock front causing the radiation to decrease. The time between these events is a decreasing linear function of the target thickness and when extrapolated to zero determines the thickness where the rarefaction would have overtaken the shock wave at the surface of the target. Light pipes are used to transmit the radiation to photomultipliers whose response is measured by high‐speed oscilloscopes.

Detonations at nanometer resolution using molecular dynamics.

Abstract: We show that discrete detonation chemistry can be studied using molecular dynamics simulations. A model 2D semi-infinite energetic molecular solid described by reactive many-body potentials is shown to support a chemically sustained shock wave with properties that are consistent with experimental results and the classic continuum theory of planar detonations. These promising results demonstrate for the first time that simulations using reactive many-body potentials provide a powerful probe of the interplay between the continuum properties of shock waves and the atomic-scale chemistry they induce in condensed-phase detonations

Rise-time measurements of shock transitions in aluminum, copper, and steel

Abstract: Time‐resolved measurements of shock‐wave rise times have been accomplished for aluminum, copper, and steel to stress levels of 41, 96, and 139 GPa, respectively, using velocity‐interferometer techniques. To within the time resolution of the technique, the shock transition is found to occur within 3 ns in all materials. Based on this upper limit for the transition time, limiting viscosity coefficients of 1000, 3000, and 4000 P are obtained for 6061‐T6 aluminum, OFHC copper, and 4340 steel, respectively, at strain rates above 108 s−1. It is found that the effective viscosity can be expressed as parameters in a Maxwellian relation for an elastic‐plastic solid, in which the viscosity is related to an effective relaxation time. It is also shown that viscosity is inversely proportional to mobile‐dislocation density, which implies that the density of mobile dislocations obtained during shock compression in these materials is well over 109/cm2.

The response of normal shocks in diffusers

Abstract: The frequency response of a normal shock in a diverging channel is calculated for application to problems of pressure oscillations in ramjet engines. Two limits of a linearized analysis arc discussed: one represents isentropic flow on both sides of a shock wave; the other may be a crude appr'l'I;imation to the influence of flow separation induced hy the wave. Numerical results arc given, and the influences of the shock wave on oscillations in the engine are discus,ed.