scholarly journals Analysis of steady compaction waves in polyurea aerogel

2018 ◽  
Author(s):  
M. A. Price ◽  
T. D. Aslam ◽  
J. J. Quirk
Keyword(s):  
Compaction Waves

Multiscale Analysis of Particle Size-dependent Steady Compaction Waves in Granular Energetic Materials

2012 ◽  
Vol 13 (2) ◽  
pp. 165-175
Author(s):  
Xin-Ming Zhang ◽  
Yan-Qing Wu ◽  
Feng-Lei Huang
Keyword(s):  
Particle Size ◽  
Liquid Phase ◽  
Yield Strength ◽  
Thermal Energy ◽  
Coarse Particles ◽  
Localization Strategy ◽  
Solid Liquid ◽  
Particle Beds ◽  
Compaction Waves ◽  
Grain Temperature

Abstract A multiscale model is used to analyze the compaction processes in granular HMX beds composed of different particle sizes (coarse particles, d=40 μm and microfine particles, d=4 μm). The localization strategy of Gonthier is extended to include changes in thermal energy induced by compression. The variation in yield strength caused by solid-liquid phase change is also considered. Analysis of the steady-state wave structure indicates that the compaction behavior of a porous material is dependent on particle size. For solid volume fraction φs < 0.88, the fine particle beds provide greater resistance to compaction than the coarse particle beds, and they propagate compaction waves that travel at faster speeds. When φs > 0.88, the physical state of the compacted bed has become very similar for the two materials. For subsonic compaction waves, the evolution of the grain temperature shows that large particles lead to large hot spots and high temperature and coarse particles are more shock sensitive at low shock pressures. For supersonic compaction waves, compression induced changes in thermal energy play an important role in localization strategy. It increases the localization sphere center radius. The dissipated energy is deposited over a larger localization volume so that the grain temperature near the intergranular contact surface is reduced significantly. The localization center radius further increases because of the decrease in the yield strength caused by solid–liquid phase change. Consequently, the peak grain temperature is reduced further.

scholarly journals Zebra rocks: compaction waves create ore deposits

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Ulrich Kelka ◽  
Manolis Veveakis ◽  
Daniel Koehn ◽  
Nicolas Beaudoin
Keyword(s):  
Ore Deposits ◽  
Compaction Waves

Compaction Wave Propagation in Layered Cellular Materials Under Air-Blast

2019 ◽  
Vol 11 (01) ◽  
pp. 1950003 ◽  
Author(s):  
Minzu Liang ◽  
Xiangyu Li ◽  
Yuliang Lin ◽  
Fangyun Lu
Keyword(s):  
Wave Propagation ◽  
Aluminum Foam ◽  
Cellular Materials ◽  
Equal Mass ◽  
Propagation Direction ◽  
Structural Components ◽  
Air Blast ◽  
Perfectly Plastic ◽  
Compaction Waves ◽  
Negative Gradient

The propagation of compaction waves in layered cellular material subjected to air-blast is analyzed to examine the mechanism of compaction wave and reveal the phenomena that develop at the interface between the cellular layers. Similar to the previous studies of cellular materials under dynamic loading, the topology of cellular materials is neglected and homogeneous properties are assumed. The rigid-perfectly plastic-locking (R-PP-L) material idealization and the simple shock theory are employed to analyze the compaction situations. Analytical solutions for compaction wave propagation of double-layer cellular materials with two gradient-arrangements under air-blast loading have been worked out. The densification wave occurs at the blast end and then gradually propagates to the distal end for layers’ densities increase in the propagation direction (positive gradient). While compaction waves simultaneously form in both layers and propagate to the distal end in the same direction for the negative gradient. The finite element (FE) models using the Voronoi technique are carried out with practical aluminum foam to verify the predictions of the theoretical analysis. The potential of layered cellular materials to design efficient structural components under air-blast load is discussed, which would outperform their corresponding single counterpart with equal mass.

Multiscale Analysis of Particle Size-dependent Steady Compaction Waves in Granular Energetic Materials

2012 ◽  
Vol 13 (2) ◽  
Author(s):  
Xin-Ming Zhang ◽  
Yan-Qing Wu ◽  
Feng-Lei Huang
Keyword(s):  
Particle Size ◽  
Energetic Materials ◽  
Multiscale Analysis ◽  
Multiscale Model ◽  
Particle Sizes ◽  
Coarse Particles ◽  
Size Dependent ◽  
Compaction Processes ◽  
Compaction Waves

AbstractA multiscale model is used to analyze the compaction processes in granular HMX beds composed of different particle sizes (coarse particles,

Dynamic and Quasi-Static Propagation of Compaction Waves in a Low-Density Epoxy Foam

2006 ◽  
Vol 46 (2) ◽  
pp. 127-136 ◽  
Author(s):  
B. Song ◽  
M. J. Forrestal ◽  
W. Chen
Keyword(s):  
Low Density ◽  
Epoxy Foam ◽  
Compaction Waves

Multiscale Shock Heating Analysis of a Granular Explosive

2005 ◽  
Vol 72 (4) ◽  
pp. 538-552 ◽  
Author(s):  
Keith A. Gonthier ◽  
Venugopal Jogi
Keyword(s):  
Phase Change ◽  
Hot Spots ◽  
Thermal Conduction ◽  
Hot Spot ◽  
Energy Localization ◽  
Two Phase ◽  
Shock Compaction ◽  
Compaction Zone ◽  
Contact Surfaces ◽  
Compaction Waves

A multiscale model is formulated and used to characterize the duration and amplitude of temperature peaks (i.e., hot spots) at intergranular contact surfaces generated by shock compaction of the granular high explosive HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine). The model tracks the evolution of both bulk variables and localized temperature subject to a consistent thermal energy localization strategy that accounts for inelastic and compressive heating, phase change, and thermal conduction at the grain scale (grain size ∼50μm). Steady subsonic compaction waves having a dispersed two-wave structure are predicted for mild impact of dense HMX (porosity ∼19%), and steady supersonic compaction waves having a discontinuous solid shock followed by a thin compaction zone are predicted for stronger impact. Short duration hot spots having peak temperatures in excess of 900K are predicted near intergranular contact surfaces for impact speeds as low as 100m∕s; these hot spots are sufficient to induce sustained combustion as determined by a two-phase thermal explosion theory. Thermal conduction and phase change significantly affect hot-spot formation for low impact speeds (∼100m∕s), whereas bulk inelastic heating dominates the thermal response at higher speeds resulting in longer duration hot spots. Compressive grain heating is shown to be largely inconsequential for the range of impact speeds considered in this work (100⩽up⩽1000m∕s). Predictions for the variation in inelastic strain, pressure, and porosity through the compaction zone are also shown to qualitatively agree with the results of detailed mesoscale simulations.

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