Parallel disks eccentricities

Oscillatory shear measurements can be done with the parallel-disk arrangement in a manner similar to the case of the cone-n-plate viscometer and, similarly, the material fimcdons i), G, C, and others can be generated. However, a slightly different tedinique [36] is at times used wherein the polymer melt sample is deformed between two oscillating parallel eccentric disks as shown in Fig. 3.2. In this case, too, it has been shown that the fluid elements undergo a periodic sinusoidal deformation and the forces exerted on the disk are thus interpreted in terms of G and G" [4]. 

Figure 1.10.1 shows two parallel disks rotating at velocity 2. The disks are separated by a distance h and their axes of rotation are eccentric or displaced by an amount a. 

Figure 3.2 Schematic diagram showing the principal features of parallel eccentric disks rotational viscometer.

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