Sample test geometries

Several sample test geometries are available with most DMA instruments. These include the following (see illustrations in Fig. 5.50) ... 

Figure 4.127 shows the creep modulus of several grades of glass fibre reinforced LCPs in various conditions of sample geometry, loading and temperature. The two samples tested... 

There are three principal problems relating to the specimen, and test geometry. These are the end effect due to gripping the sample, the alignment of the specimen in the test equipment, and the shape of the specimen itself. We shall deal with each of these separately. 

Effect of Sample Holder Geometry on Pressure-Time Curves of Lead Dioxide-Cupric Oxide-Silicon Starter Composition A New Test Fixture Design , NAVAMDEP RDTR142, Crane (1969) 9a) J.R, Gibson J.D. Weber, Hand-... 

The total combination of data obtained permitted optimization of process variables relative to reactor geometry employed, and optimization of carbon black quality produced. The array of samples tested enabled us to prepare a mathematical relationship of these principal variables to commercial feedstock properties. 

The testing geometry is shown in Fig. 2. Specimens were prepared from compression-moulded rectangular plates of 170 x 200 mm, which were sawn into 80 x 25 mm samples, about 10 mm thick. 

The test geometries listed in Table 2-2 are those commonly used for instruments that can apply rotary motion, either in the form of a controlled torque or a controlled amount of rotation. The listed examples can as a set handle samples from stiff viscoelastic solids to freely flowing liquids. All are... 

Specially constructed cells are used to measure the gas transmission rate. After a film sample has been clamped into a cell, test gas is flushed through chambers on both sides of the sample. Test gas is admitted to one side of the sample the test chamber on the other side is evacuated, and gas is allowed to permeate through the film sample into the evacuated chamber for a measured length of time. Using the geometry of the cell and film sample, with the measured pressure and temperature of the test gas which permeated the sample, the GTR can be calculated. (See Fig. 

Further development of the indentation depth measurement method seems to be imminent when semiconducting diamonds are cut to the Vickers geometry and used to indent conducting specimens. At the moment the samples tested have been metals, but many special ceramics like TiC, TiN, SiC, and MWO3 are electrically conducting and could be investigated. The method involves sensitive measurement of electrical resistance as a function of indenter load. 

Further the dependences of effective fracture energy t/ on sample fracture surface effective area S j. can be plotted and determined the values and can be determining, characterizing a polymer plasticity. It is clear, that in the Eq. (10.21) U j. = U, S j. = BD0 and in the Eq. (10.22) C/j = 2U,. Let us note, that the parameters and are polymer property and in virtue of this they should not depended neither on testing geometry nor on their determination mode [23, 44]. 

If the original sample has the normal test geometry, the neck takes the form of a tape, as illustrated. However, if the sample is an extrudate like a thick fibre, the drawn neck is a very thin, but very strong, high modulus fibre. 

Fig. 5. Static shear test geometry. Load, F, is applied by hanging a weight from a sample adhered to a panel with a rectangular overlap area.

There are a number of index tests in which the flow is driven by drag. Most are based on rotating a disk or other complex shape in a large quantity of the sample. These geometries are used because they are easy to load or because they help sample mixing. 

Figure 16.8), where the cyclic load (stress or strain) can be applied, with the resulting strain or stress measured. For liquid samples, the geometries discussed in conjunction with rotational viscometry are often used with the drive system modified to produce sinusoidal rather than steady rotational deformation. Flexible samples such as libers, films, and rubber are preloaded in tension and oscillated about a positive tensile strain so that they do not go slack at the bottom of the sine wave. Such tests give dynamic tensile properties, E, E", etc., which are related to the corresponding shear properties by... 

---