Measurement of mechanical strength

The mechanical properties of solid propellants are discussed by Kelly [25]. In the U S.A. the methods are based on instructions worked out by a Joint-Army-Navy-Air Force (JANAF) Physical Properties Panel and include uniaxial and multiaxial measurements of mechanical strength. 

Note TTie variable E in this chapter refers to the activation energy for flow (which is important when studying rheology). However, the modulus of elasticity, which is a measure of mechanical strength, is also represented by E, as first introduced in Chapter 13. 

The tensile test is performed by placing a specially shaped specimen in the heads of the testing machine. The specimen is pulled apart through a hydraulic or mechanical loading system (Figure 15.33). Most ordinary tensile tests are conducted at room temperature and the tensile load is applied slowly. The unit measure of tensile strength is the pascal (Pa), or newtons per square meter (N-nf2), and is defined by the following equation ... 

Oxidation parameters can be used instead of mechanical strength to measure very early stages of degradation by oxidation [14, 15]. 

Thus, the introduction effect of long-chain alkyl groups into the DAP resins was reflected in the improved flexibiiity. In particular, LMA and SMA as comonomers showed a remarkable effect for example, the DAP resin cocured with 10 mol% of LMA had the tensile strength of 600 kg/cm and the elongation of 9.0%, although the DAP resin obtained by homopolymerization was quite brittle and, therefore, could not even be subjected to the measurement of mechanical properties as mentioned above. 

Miller, B., Gaur, U- and Hirt, D.E. (1991). Measurement of mechanical aspects of the microdebond pullout technique for obtaining fiber/resin interfacial shear strength. Composites Sci. Technol. 42,207-219. 

The micromanipulation technique has been used to measure the mechanical strength of microcapsules of different size, shell thickness and shell composition (Sun and Zhang, 2001,2002 Xue and Zhang, 2008 Zhao and Zhang, 2004 Zhang et al., 1999). For example, the mechanical... 

A number of micromanipulation-based techniques have been developed and used to measure the mechanical strength of single particles,... 

The electrical response of a liquid-loaded TSM resonator can be related to the shear mechanical impedance, Z, at the device surface. This mechanical impedance serves as a quantitative measure of the strength of the interaction between the solid and a contacting liquid. 

The constant of proportionality (k) in both cases is the stretching force constant and, in the same way that a force constant can measure the strength of a mechanical spring, k gives a measure of the strength of a chemical bond. Indeed, the force constant measures bond strength when the atoms are near their equilibrium positions, a far more subtle measure than the dissociation energy. 

Quantity Ce is a measure of the strength of long-range intemiolecular attractions. Fractional contributions of tlie tliree mechanisms to long-range forces are ... 

The slope of a plot of the log of the retention time versus the inverse of the temperature is proportional to the enthalpy of retention for the probe molecule on the coal. This is a thermodynamic measure of the strength of the interaction between the probe molecule and the coal. The temperatures at which major changes in slope are observed represent the points where the mechanism of retention has changed, indicating that a significant change in the chemical or physical structure of the coal has occurred. 

The focus of this study is the process of adsorption. The adsorption of substances onto solid suspended phases is a primary mechanism for the removal of dissolved matter from the water column and the consequent accumulation of many substances in sediments. Of major concern is the value of the adsorption constant (Kads) which is a measure of the strength of the adsorption interaction. Knowledge of the variation in Kads with changes in experimental condi-... 

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