Impact planar

Samples are most frequently shock deformed under laboratory conditions utilizing either explosive or gun-launched flyer (driver) plates. Given sufficient lateral extent and assembly thickness, a sample may be shocked in a onedimensional strain manner such that the sample experiences concurrently uniaxial-strain loading and unloading. Based on the reproducibility of projectile launch velocity and impact planarity, convenience of use, and ability to perform controlled oblique impact (such as for pressure-shear studies) guns have become the method of choice for many material equation-of-state and shock-recovery studies [21], [22]. 

More important, tire surface curvature of tire carbon network exerts a profound impact on tire reactivity of tire fullerene core [6, 7]. In tliis context, tire most striking consequence emerges from tire pyramidalization of tire individual carbon atoms. Influenced by tire curvature, tire sp hybrids which exist in tmly two-dimensional planar... 

Planar shock waves can be produced simply by using a gun to accelerate a flat-nosed projectile which then impacts onto a flat specimen (Fig. 3.3). The... 

Figure 3.2. Explosive plane-wave generator used to accelerate a flyer plate for planar impact on a specimen.

In most flat-plate impact experiments, the direction of motion of the impacting plate is normal to its surface, such that only a planar compressive shock is introduced into the specimen. Within the last fifteen years, however, techniques have been developed for dynamic pressure-shear loading of specimens (Abou-Sayed et al., 1976 Chhabildas and Swegle, 1980). These involve an oblique impact, as illustrated in Fig. 3.6, in which the impact surface on the... 

The most common form of energy deposition used for planar shock wave research has been electrical resistance heating of a metal foil which vaporizes, driving a flyer plate to a high velocity before it impacts a specimen. In a hybrid system incorporation both resistance vaporization and an electromagnetic push, velocities to 18 km/s are reported for kapton flyer plates which are... 

Figure 7.2. Response of elastic-plastic solid to planar impact at X = 0 u = longitudinal particle velocity. Measurements are made as a function of time at fixed Lagrangian position X.

A common experimental method for creating a region of spall is through the flat impact of plates of material. Such impact leads to a process of planar spall in which an interior planar region of material is carried into tension and failure occurs through a process of crack formation or hole cavitation. Much... 

Impact of a thin plate on a sample of interest which is, in turn, backed by a lower impedance window material leads to an interaction of waves which will carry an interior planar region into tension. Spall will ensue if tension exceeds the transient strength of the test sample. A velocity or stress history monitored at the interface indicated in Fig. 8.4 may look as indicated in Fig. 8.5. The velocity (stress) pull-back or undershoot carries information concerning the ability of the test material to support transient tensile stress and, with appropriate interpretation, can provide a reasonable measure of the spall strength of the material. 

Figure 8,4. The planar impact configuration is illustrated showing the spall plane in the sample and the interface at which time-resolved stress or particle velocities are measured.

To arrive at a perspective on magnitudes of pressure, consider two types of loadings, planar impact and planar detonation of high explosives, which are perhaps the two most common procedures. Figure 1.1 shows shock-... 

The free t-butyl cation [7" ] in the gas phase is nothing more than a species detectable by the electron impact method (Yeo and Williams, 1970). However, it is not only an observable species by nmr studies in SbFs/FSOsH (Olah et al., 1964), but can be isolated from the solution in the form of its SbF or Sb2Ffi salt (Olah and Lukas, 1967a,b Olah et al., 1973 Yannoni et al., 1989). The crystal structure shows that this ion is planar and its carbon-carbon bonds are shortened to 144.2 pm (Hollenstein and Laube, 1993). Its particular electronic stabilization among aliphatic carbocations is attributed by physical organic chemists to the operation of both inductive and hyperconjugative effects in the cr bond system. 

Undoubtedly, the uniform structural and spectral behavior of the trigonal-planar jt-radicals (t-Bu2MeSi)E (E = Si, Ge, Sn) 43-45 both in the solid state and in solution should be ascribed to the immediate impact of the bulky electropositive silyl substituents. In contrast, it is well known that simple alkyl and aryl substituents cause a highly pronounced pyramidalization at the radical centers, where the unpaired electron typically occupies the orbital with a high s-contribution (o-radicals)7 ... 

Sensitivity impacts upon the limit of detection and resolution of the device, making it a key performance parameter. Recently, several strategies have been developed in order to provide sensitivity enhancements for optical sensor platforms based on both optical absorption and fluorescence phenomena. These strategies are the result of rigorous theoretical analyses of the relevant systems and, combined with polymer processing technology and planar fabrication protocols, provide a viable route for the development of low-cost, efficient optical sensor platforms. 

Arthur D. Little has carried out cost structure studies for a variety of fuel cell technologies for a wide range of applications, including SOFC tubular, planar and PEM technologies. Because phenomena at many levels of abstraction have a significant impact on performance and cost, they have developed a multi-level system performance and cost modeling approach (see Figure 1-15). At the most elementary level, it includes fundamental chemical reachon/reactor models for the fuel processor and fuel cell as one-dimensional systems. 

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