Shock response of dry sand.

Abstract

The dynamic compaction of sand was investigated experimentally and computationally to stresses of 1.8 GPa. Experiments have been performed in the powder's partial compaction regime at impact velocities of approximately 0.25, 0.5, and 0.75 km/s. The experiments utilized multiple velocity interferometry probes on the rear surface of a stepped target for an accurate measurement of shock velocity, and an impedance matching technique was used to deduce the shock Hugoniot state. Wave profiles were further examined for estimates of reshock states. Experimental results were used to fit parameters to the P-Lambda model for porous materials. For simple 1-D simulations, the P-Lambda model seems to capture some of the physics behind the compaction process very well, typically predicting the Hugoniot state to within 3%.

Response to Unloading and Reloading of Shock Compressed Polymethyl Methacrylate

“…This simple wave Figure 4. The simplicity of the input wave suggests that any complex response observed in a target material of interest [6] would not be from the impactor. Figure 5 provides the reloading and unloading data up to 130 GPa.…”

“…The results from these experiments will provide another tool to investigate not only strength of materials in the reshocked state, but to investigate phase transitions in materials that have small volumetric changes [6]. PMMA will be backed by different high-impedance materials, using multiple experiments on a two-stage light gas gun projectile.…”

Numerical modelling study of a modified sandbag system for ballistic protection

“…The major threat from blast is the propagation of the shockwave through the material [4,5]. Sand resists blast by undergoing densification due to the pressure load from the shockwave [6,7].…”

“…While experimental impact studies allow for a clear observation of the response of sand to dynamic loading, they pose a challenge with regards to the quantification of this response [6]. The use of sensors and high speed cameras along with processes such as digital image correlation have been used in recent years to measure the response of sand to impact and study its energy absorption characteristics [8].…”

Mesoscale simulations of shock compaction of a granular ceramic: effects of mesostructure and mixed-cell strength treatment

“…These processes are vital for understanding large-scale shock events, such as asteroid collisions and detonations, and are instrumental in defending against them. A great deal of experimental research into the bulk response of granular materials, especially ceramics and sand, currently exists [1][2][3][4][5][6]. However, the high strain-rates and short timescales involved in shock compaction have made experimental work into granular dynamics challenging.…”