Elastic response, defined, figure

The phase angle changes with frequency and this is shown in Figure 4.7. As the frequency increases the sample becomes more elastic. Thus the phase difference between the stress and the strain reduces. There is an important feature that we can obtain from the dynamic response of a viscoelastic model and that is the dynamic viscosity. In oscillatory flow there is an analogue to the viscosity measured in continuous shear flow. We can illustrate this by considering the relationship between the stress and the strain. This defines the complex modulus ... 

Each type of propellant has specific mechanical characteristics, but the influence of test parameters (temperature, strain rate, and pressure) is the same for all propellants (11). Tensile tests are widely used to analyze propellant behavior as well as examine the manufacturing controls of the propellants. Because their behavior is not linear-elastic, it is necessary to define several parameters that allow a better representation of the experimental tensile curve. The stylistic experimental stress-strain response at a constant strain rate from a uniaxial tensile test is shown in Figure 7, where E is the elastic modulus (initial slope), Sr P is the tensile strength (used later for a failure criterion), and eXj> is the strain at tensile strength. 

Presently, the study of shape memory polyurethane (SMPU) has been widely conducted. For common elastic fibers, the elasticity should be defined as the instant recoverability of the length on release of the deforming stress. The recovery in shape memory fibers is the ability of deformed fibers to recover under external stimulus such as heat or chemicals. In this case, the external stimulus is a must. Figure 3.1 shows the net-points and switches which response to the stimulus (Hu et al., 2012). The elongation of shape memory polymer fiber are a little less than spandex, but mechanical... 

An elastomer may be defined as a crosslinked polymer network whose temperature is above its glass transition temperature. The molecular mechanism responsible for rubber elasticity is based on changes in chain conformation brought about by the overall strain (see Figure 1.13). Clearly, the number of possible chain conformations must be fewer in case (c) than in case (a), resulting in a reduction of entropy (Flory, 1953, Chapter 11). Statistically all possible chain conformations are equally likely, assuming negligible... 

The fringe elasticity we have just discussed has some remarkable consequences. In particular, it is responsible for the very special profile of a line that is slightly pinched. As indicated in Figure 3.3, let us assume that a weak force (due, for example, to a surface defect) is applied at point O of the substrate. What shape does the line of contact adopt The answer requires solving an equation similar to (3.5), but one that includes a localized force / defined by... 

---