Shear test sample schematic

Figure 2. Schematic diagram of shear test samples.

Figure 1 shows the entire test system in schematic form. The test sample is comprised of two specimens of a viscoelastic damping polymer loaded in shear by force from an electromagnetic shaker. Each specimen is cemented between a centrally located, driven steel sample block and one of two clamped reaction blocks. The dimensions of each block in this apparatus are 25.4mm height,... 

Shear cells can be used to study attrition effects in particles under compression (Ghadiri and Ning, 1997). One example is the direct shear cell, which usually consists of two halves one on top of the other the one at the top has a replaceable lid that covers the powder and acts like a piston. A schematic diagram of a shear cell is shown in Figure 12. In this case, the compartment at the base is mobile. When a sample is put in the shear cell and compressed under normal force by the lid, the base compartment can be placed in motion by a horizontal shearing force. Once they are filled with the particulate material of known particle size (or size distribution) the test sample is... 

The test method consists of uniaxially straining a sample of the film-substrate couple as shown schematically in Figure 1. The film thickness is t, and the specimen width is w. Under tensile strain, an interfacial shear stress, x(x), is produced. While the film is bonded to the substrate, the shear stress, x(x), at the interface causes a tensile stress, metal film. When the strain is sufficient, the tensile stress will reach the ultimate tensile strength of the film, tr. Then, if the film fails by brittle... 

Finally, Figure 14.5d shows a schematic of simple shear deformation. The specimen is clamped between steel blocks. The blocks must move parallel to each other in order to get a shear strain that is uniform along the waisted region. The shear stress is calculated as t = F/A, where F is the force applied to the plane of area A. In this test it is not necessary to distinguish between nominal and true stress because the shear strain does not affect A. The shear strain is defined as y = Ax/y, where Ax is the displacement of planes separated by a distance y. Ax being measured in the direction of the force applied, which is perpendicular to y. As in the case of the compression plane strain test, there is no change in the dimension of the sample along the z axis. 

With these requirements an automated multistation tester was built and controlled by an inexpensive microcomputer. Five samples were run simultaneously with linear variable differential transformers (LVDT s) monitoring the shear adhesion process to a resolution of better than 10 inches. Testing surface temperatures were measured and controlled to + 0.05°C. Via a data compression scheme, the entire event regardless of length of time can be represented by thirty data points or less. In this study, smooth stainless steel surfaces were used. The schematic diagram for the apparatus is presented in Fig. 2. 

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