Critical friction energy

Fig. n.18 Critical friction energy of mixtures of AP + liquid organoiron and AP + boron catalysts is decreased with increasing mass fraction of these catalysts. 

When the catalysts are in the form of crystalline solid particles, the characteristics of Efc are different compared to when liquid organoiron catalysts are used. As shown in Fig. 11.18, the critical friction energy is independent of the mass fraction of the catalysts SrCOj and FcjOj. Though Fe203 reduces the Ef similarly to the... 

Fig. n.19 Critical friction energy is decreased when the critical ignition temperature is lowered for both or-ganoiron and boron catalysts. 

Fig. 11.21 shows the results of TG and DTA measurements on mixtures of AP particles and catalysts. The endothermic peak observed at 513 K is caused by the crystal structure transformation of AP from orthorhombic to cubic. A two-stage exothermic decomposition occurs in the range 573-720 K. The decomposition of the AP is seen to be drastically accelerated by the addition of catocene. The exothermic peak accompanied by mass loss occurs before the AP crystal transformation. Although the AP is sensitized by the addition of carborane, no effect is seen on the AP decomposition. The results indicate that carborane acts as a fuel component in the gas phase but does not catalyze the decomposition of AP. Thus, the critical friction energy is lowered due to the increased reaction rate in the gas phase. The results imply that the initiation of ignition by friction is caused by the ignition of the gaseous products of the AP pyrolants.PI... 

Also, the friction sensy which is stated as 12 kp pistil load ] 28) M.Ya. VasiTev, Dependence of the Critical Excitation Energy of Explosion by Impact on the Density of Explosives , Deposited Doc, VINITI, 1247-76 (1975) CA 88, 76093... 

In variable mechanical fields (the type of loading that occurs during friction) the slowest stage that defines the velocity of tribochemical transformations may turn out to be redistribution of elastic stresses in the polymer. In this case, the velocity constant Ki of the mechanical process will be proportional to the redistribution velocity j4(s ) and the probability of accumulating some critical deformation energy U on a given link sufficient for the reaction initiation [82] will be... 

The earlier analysis considers only the energy balance in the fibre itself. Subsequently, Stang and Shah [58] developed a solution which takes into account the compliance of the entire puii-out system. Morrison etal. [57] further extended the anaiysis by taking into account aiso the frictional resistance in the debonded zone, which is the more realistic case for FRC composites. The critical strain energy release rates for debonding calcuiated by Morrison et al. [57], 2.5 N/m, were simiiar to those calculated by Mandel etal. [59], of 4-7.4 N/m. These values are, however, lower than typical values of the critical strain energy release rate of plain... 

Studies based on the Frenkel-Kontorova model reveal that static friction depends on the strength of interactions and structural commensurability between the surfaces in contact. For surfaces in incommensurate contact, there is a critical strength, b, below which the depinning force becomes zero and static friction disappears, i.e., the chain starts to slide if an infinitely small force F is applied (cf. Section 3). This is understandable from the energetic point of view that the interfacial atoms in an incommensurate system can hardly settle in any potential minimum, or the energy barrier, which prevents the object from moving, can be almost zero. 

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