Loading and unloading curves

Figure 8 Loading and unloading curves for a single 163 pm diameter ion-exchange resin particle (DOWEX 1X8-200, Sigma-Aldrich, UK) obtained at a speed of 22.4 pm s 1 (data provided by T. Liu).

As could be expected, the mechanical properties of a crazed polymer differ from those of the bulk polymer. A craze containing even 50% microcavities can still withstand loads because fibrils, which are oriented in the direction of the load, can bear stress. Some experiments with crazed polymers such as polycarbonate were carried out to get the stress-strain curves of the craze matter. To achieve this aim, the polymer samples were previously exposed to ethanol. The results are shown in Figure 14.24 where the cyclic stress-strain behavior of bulk polycarbonate is also illustrated (32). It can be seen that the modulus of the crazed polymer is similar to that of the bulk polymer, but yielding of the craze occurs at a relatively low stress and is followed by strain hardening. From the loading and unloading curves, larger hysteresis loops are obtained for the crazed polymer than for the bulk polymer. 

Fig.4. Data profile of the loading and unloading mechanisms of the blister test for dynamic debonding process. Refer to the text for details of loading and unloading curves ffv), g(v) and duration of debonding time. t=b-a.

Fig. S. Responiie of a viscoelastic bioniaierial to mechanical preconditioning. Sliess-strain curves are displaced to the right, and hysteresis (the difference between loading and unloading curves in a cycle) decreases.

A small hysteresis between tensile loading and unloading curves was detected. The total strain is regained. Those processes are defined as anelastic ones. A temperature change occurs during deformation (adiabatic process). Thus, anelastic processes should depend on the strain rate, e, but this was not found in the experiment. This point cannot be explained. 

Dielectric measurements also can be performed in capacitors placed inside adsorption columns. Here they provide a means to detect adsorption processes on site , i. e. to observe changes in the electric capacitance of the capacitor due to gas adsorption or desorption processes on the sorbent material in the capacitor. In this way not only breakthrough curves but also periodic loading and unloading curves of sorptive gases in laboratory or industrial adsorption reactors can be observed. 

Figure 2.15. Loading and unloading curves for a Lancaster micro-indentation test of a 2-/tm-thick film of TiN. ...

The biomechanical behavior of normal human ankle joint during walking has been examined in several studies. It has been shown that ankle joint has viscoelastic behavior with two distinct components of stiffness elastic and viscous [1, 2]. In some studies the slopes of the moment-angle loop in loading and unloading curves have been defined as quasistiffness [3, 4]. The other component viscous hysteresis has been demonstrated as an area between loading and unloading curves [1,5]. 

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