Penetration velocity

Of samples swollen with ethylene diamine, the graft yield at a 50 1 liquor ratio increases as the concentration of ethylene diamine increases. This is due to the increase of decrystallization of swollen samples, which helps the penetration velocity of the chemicals through the cellulosic chains. Graftability of the samples treated with 100% ethylene diamine is lower that of the sample treated with 75%. This is due to the dissolution of low DP chains and some of the hemicelluloses, which is detectable by the increase in DP of the sample teated with 100% ethylene diamine. 

The hydrodynamic theory of the penetration of targets by lined cavity jets was developed, according to Cook (Ref 7, p 252), independently by Pugh (Birkhoff s et al Ref 2) and by Hill et al (Ref 1). Pack Evans (Refs 3 4) discussed the steady-state theory of penetration in which the jet-velocity. distribution was ignored and the penetration velocity was assumed constant. Pugh, 8t Eichelberger (Refs 5 6) discussed the nonsteady-state of jet penetration in which, the actual velocity distribution in the jet was taken into account as well as the variation of the velocity of penetration with.depth These theories are discussed by Cook (Ref 7) Refs 1) R. Hill, N.F. Mott D.C. Pack, Unpublished "Ministry of Supply Report, January 1944 2) G. Birkhoff, D.P. Mac-... 

Dissolution measurements under the microscope give several results which will be discussed separately. The first and most evident result is the penetration velocity of the solvent into the polymer. In order to judge the influence of the solvent s chemical constitution on the polymer we have chosen a number of phthalic acid esters which differ only in their ester groups and which are well known plasticizers. The polymer was a vinyl chloride-vinyl acetate (87 13) copolymer. The following plasticizers have been tested, (the abbreviations are indicated)... 

The penetration velocity is influenced mainly by the viscosity of the plasticizer. We can conclude this from Figure 10 which shows the dependence of penetration velocity, i, expressed in cm. sec.-1, on the viscosity of the solvent, expressed in... 

Kinetic effects were determined by measurements of dissolution and penetration rates. A constant penetration velocity was observed for almost all compositions for both binary solvent mixtures. In all studies, case II transport assumptions provided good agreement with experimental results. For MEK-IPA, penetration rates increased with increasing MEK concentration. For MIBK-methanol, however, a maximum penetration rate was observed at a 60 40 MIBK/methanol ratio. 

Since the permeance and permeability are always different from zero, no permeation is equivalent to zero permeation driving force, which occurs when the species partial pressures on both membrane sides are equal to each other. It must be noted that the equilibrium conversion of an MR is independent of the permeation law that expresses the penetrant velocity through the membrane materials. 

Fig. 2.2 Piston flow of water infiltrating into a homogeneous granular soil (sponge-type flow). A layered structure is formed, lower water layers being older than shallow ones. Penetration velocities are observed to range from a few centimeters to a few meters per year.

The time it takes to complete the penetration is found from the penetration velocity and the depth of penetration. 

To simplify the problem, let us assume that the circle of contact is constant. The modulus of the penetration velocity will be given by... 

Vjj is defined as the average of an equal number of highest partial penetration velocities and lowest complete penetration velocities occuring within a specified velocity spread. A minimum of two partial and two complete penetration velocities is used to complete the Four, six, and ten rounds are frequently used. CunnifF normalised the fabric energy absorption through dividing (v/- v ) by v/, which is plotted as a... 

Penetration velocity of a molten core in the containment floor ... 

The specimen s compaction is carried out using the proctor method in accordance with CEN EN 13286-2 (2012) (normal or modified compaction, whichever is chosen), whereas the diameter of circular piston (50 5 mm), the piston s penetration velocity (1.27 mm/min) and the rest of the procedure are similar to the American standard. 

General experience has shown that addition of a surfactant to the liquid leads to an increased velocity by which the liquid displaces air. The surfactant adsorbs at the LG and SL interfaces. The observation of increased penetration velocity indicates a dominant effect of the reduction in y . As y ° cos 0 = y < - y - (and essentially being unaffected because 0), a reduction in y - corresponds to a higher value for y ° cos 0, which, according to Equation 8.20, implies a proportional increase of the penetration velocity. 

Other attempts to describe mold filling quantitatively were the studies [10-13] that treated the fiow as if it were isothermal. One set of results [10-12] yielded calculated results that gave curves of pressure vs injection rate that were displaced from experimental results. The other study [13] gave curves of pressure cavity thickness that matched experimental results. In addition, calculated penetration velocity-time data matched the results shown in Fig. 8-17. 

For this reason, another strategy was pursued to characterize the wettability of porous media (44). This strategy is also based on a modified Washburn equation. By plotting Kyiv cos B versus the liquid surface tension yiv, the solid surface tension, ysv can be directly derived from these curves. The term K yiv cos 0 is obtained indirectly from capillary penetration experiments, when the liquid properties and the penetration velocities are known K is an unknown parameter that depends on the geometry of the porous medium). This approach is based on the following considerations. 

The penetration velocities of projectiles interacting with explosives initiated by the projectile have been found to be much lower than the penetration velocities of inerts of the same density. Studies of projectile penetration dynamics in inert and reactive targets have been performed using the Eulerian reactive hydrodynamic code 2DE described in Appendix C. 

Using this expression to determine the penetration velocity for a 1 cm/ps steel jet interacting with various targets gives the following results. 

Bernoulli s theorem is for steady motion of an incompressible, uniform fluid. For a compressible fluid, the ideal penetration velocity expression is exact for only a constant density system however, the experimental penetration data from many studies of inert jets penetrating inerts are adequately described using the ideal model. 

Copper jet penetration into an aluminum target was calculated by Johnson using his two- and three-dimensional Eulerian hydrodynamic codes. His calculated penetration velocity agreed with the ideal values. 

The penetration velocity of a 1.3 cm diameter steel ball moving at various velocities and impacting a 2.5 cm thick cylinder of PBX-9404 or Composition B was reported by Rice. The data were generated at Ballistic Research Laboratory by R. Frey. Experimental data and Eulerian calculations by Rice indicated that the penetration velocity was markedly decreased, beyond the critical projectile velocity for initiation of detonation, and was signiflcantly less (less than half) than predicted by the ideal model. 

For jets and targets of the same material, Vp = 0.5V - for both the initial shock match across the interface and for the later penetration after steady-state is achieved, while the pressure decreases from ptUs Vp to 0.5ptVp. The high pressure near the rod-target interface supported a lower pressure shock wave that moved out into the target ahead of the rod-target interface with a shock speed similar to the penetration velocity of the rod. 

Rice reported Frey s data for the penetration velocity of a steel ball, 1.3 cm in diameter, moving at varying speeds and striking 2.5 cm thick cylinders of either PBX-9404 or Composition B. 

This system has been modeled numerically and the results have been compared with the experimental data of Frey. The mesh was 0.05616 cm by 0.05 cm and the time step was 0.005 ps. The computational problem was 78 cells in height and 20 cells in width. Figure 5.29 shows the experimental data and the calculated results of a steel ball interaction with PBX-9404 or Composition B. The ball velocity loss is defined as the initial ball velocity less the penetration velocity. The agreement demonstrates that the model describes the important process of the explosive penetration. 

When the steel ball penetrates inert or nearly inert explosive, the penetration velocity could be described by the ideal model. When the ball velocity was just sufficient to cause propagating detonation, however, the observed and calculated penetration velocities were much less than predicted by the ideal model. 

The lowered penetration velocity of a projectile moving into detonating (rather than nondetonating or inert) explosives is caused by the higher pressure at the projectile-detonation product interface. 

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