Static hysteresis measurement

The ferroelectric sample is pre-polarized by measuring a complete hysteresis. The excitation voltage is then kept constant for the relaxation time at a particular voltage. The relaxed 

After cycling once again through a complete hysteresis to ensure the same initial condition the excitation signal is stopped at the next voltage for the relaxation time. The relaxed polarization is again determined as described above. The whole procedure is repeated for each point until a complete quasi static hysteresis loop has been recorded. 

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Static performance measurements related to positioner/ac tuator operation are conformity, measured accuracy, hysteresis, dead baud, repeatability, and locked stem-pressure gain. Definitions and standardized test procedures for determining these measurements can be found in ISA-S75.13-1989, Method of Evaluating the Performance of Positioners with Analog Input Signals and Pneumatic Output . 

In Figure 3.12 a static hysteresis loop is shown in correlation to a dynamic hysteresis loop. Two clippings of the excitation signal of the static hysteresis loop are shown. Each of them is used to measure one data point of the curve. To record 20 points for one loop, 20 of these excitation signals have to be applied to the sample, each one stopping at a different voltage. 

Figure 3.12 Typical measurement result of the static hysteresis and curve of the excitation signal to measure two consecutive data points of one and the same static hysteresis loop (below).

The creep deformation behavior of TPU under static load can be determined by dynamic hysteresis measurements in reduced testing times without the risk of changing morphoiogy. 

It is demonstrated that the quasi-static stress-strain cycles of carbon black as well as silica filled rubbers can be well described in the scope of the theoretic model of stress softening and filler-induced hysteresis up to large strain. The obtained microscopic material parameter appear reasonable, providing information on the mean size and distribution width of filler clusters, the tensile strength of filler-filler bonds, and the polymer network chain density. In particular it is shown that the model fulfils a plausibility criterion important for FE applications. Accordingly, any deformation mode can be predicted based solely on uniaxial stress-strain measurements, which can be carried out relatively easily. 

Hysteresis is a static phenomenon, but its measurement requires displacement of the contact line (fig, 5.4). Immediately the question is raised as to what are the... 

We can now collect together the various characteristics of a measurement system, except for hysteresis, and express the general model for the system in the form of a block diagram. Such a block diagram representation is shown in Figure 4. The dynamic and static characteristics are shown decoupled in the diagram. The dynamic characteristics will be discussed shortly. 

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