Tensile test parameters

Figure 13.4 shows the variations between the tensile test parameters for the PP/interfacial modifier/talc composites as a function of either the grafted group, succinic anhydride (SA) or succinyl-fluorescein (SF) attached to an atactic polypropylene, as well as the differences on tensile strength and strain levels at yield or at break points, depending on the amorphous or semicrystalline nature of the interfacial modifier as it was fully discussed elsewhere (29,31). 

Figure 13.4 Macroscopic responses by changes at the interfacial level. Variations on tensile test parameters with the amount and the structure of the interfacial modifiers for the PP/talc system. (From Reference 29 with permission of Elsevier.)...

The tensile test parameters are shown in Table 2. An assembly of a 100 mm lens in high-speed... 

Tensile testing is susceptible to invalid runs due to sample flaws, poor mounting, or many other other sources of error. It is therefore essential that outliers be identified and removed. After all runs have been analyzed, STRESS calculates means and standard deviations for each parameter. It also performs Student t-tests on... 

Figure 5 presents the results of tensile tests for the HPC/OSL blends prepared by solvent-casting and extrusion. All of the fabrication methods result in a tremendous increase in modulus up to a lignin content of ca. 15 wt.%. This can be attributed to the Tg elevation of the amorphous HPC/OSL phase leading to increasingly glassy response. Of particular interest is the tensile strength of these materials. As is shown, there is essentially no improvement in this parameter for the solvent cast blends, but a tremendous increase is observed for the injection molded blend. Qualitatively, this behavior is best modeled by the presence of oriented chains, or mesophase superstructure, dispersed in an amorphous matrix comprised of the compatible HPC/OSL component. The presence of this fibrous structure in the injection molded samples is confirmed by SEM analysis of the freeze-fracture surface (Figure 6). This structure is not present in the solvent cast blends, although evidence of globular domains remain in both of these blends appearing somewhat more coalesced in the pyridine cast material.

In some ways modem tensile testing machines have reduced the need for a separate, particularly simple, routine control test. However, a test which is both simple in the sense of measuring one parameter and provides a relaxed modulus is intrinsically attractive. Such tests in various forms have existed for a long time but do not seem to have attained widespread popularity. A version in which a fixed stress is applied and the elongation after 1 min noted is given in ASTM D145689. A specific instrument developed for this... 

Ciyo-SEM methodology also facilitates the observation of highly hydrated systems. Harker and Sutherland [69] used the ability of cryo-SEM to preserve the structural integrity of the aqueous phase to characterize differences between mealy and non-mealy nectarines. The presence of juice on the surface of cells in non-mealy nectarines was observed after tensile tests produced a fractured surface. Such observations would not have been possible with conventional methods where dehydration and critical point drying are essential steps. A strong point to this study was the extensive use of other physical and chemical methodologies to help correlate textural difference based on storage parameters for nectarines. 

Various mechanical testing methods have been used to assess the bioadhesive properties of materials and formulations. Review of the literature reveals that the technique most commonly used is the tensile test [82,85]. This test provides the measure of the force needed to detach a layer of the tested material or formulation from a mucosal substrate as a function of the displacement occurring at the bioadhesive interface. Besides maximum force of detachment, another parameter provided by tensile test is the work of adhesion calculated as the area under the force versus displacement curve. Such a parameter gives more complete... 

Besides impact testing, quasi-static measurements are carried out to assess the Young modulus, E, the yield stress, cry, and the elongation at break, break> as the most current parameters. They follow international standards (e.g. ISO 527 for tensile tests, ISO 178 for bending measurements). 

As mentioned earlier, the Gc value required to define the CZ model is obtained from TDCB tests. The remaining parameter Gm is chosen as the UTS, and was extracted from the stress-strain curves at the corresponding rates. This was an arbitrary choice, since the level of the constraint near the crack tip is higher than that in uniaxial tensile tests used to obtain the stress-strain curves. Therefore, a sensitivity study on this parameter was performed. For illustration purposes, a numerical analysis carried out on TDCB test specimens bonded with the two adhesives under investigation is shown in this section. The value of a was varied from 20 to 80 MPa and numerical predictions of load versus time were compared against the experimental results. Fig. 5 shows a comparison of the FV and experimental results for different values for TDCB tests performed at 0.1 mm/min. The best fit G value should be able to predict correctly both the experimental force and crack history. (Note that the latter was found to be less sensitive to changes of the cohesive strength.)... 

A tensile test on the peel arm is used to obtain the parameters of elastic modulus, plastic modulus and yield strain. In this test, it has been necessary to use an extensometer for measuring strain at small magnitudes (i.e. up to about 2%) in order to obtain sufficient accuracy in the determination of Ei. It is also important to continue the tensile test to fracture, in order to define enough of the plastic region for an accurate... 

It is shown that the composite adhesion or bond quality is dependent on the PA-6 modification as examined by tensile test. The processing parameters are not optimised to obtain the highest values for the tensile strength. The aim of this investigation was the determination of the influence of the increase of carboxylic acid... 

Tensile tests at room temperature have shown that HPT-processed titanium demonstrates yield stress higher that 800 MPa, ultimate strength of 980 MPa and elongation to fracture of 12% (Fig. 5). A strain-rate jump test of this material has revealed an increased strain rate sensitivity value of 0.12-0.15, which is visibly higher than that for conventional coarse-grained Ti where this parameter is less than 0.05. 

Each type of propellant has specific mechanical characteristics, but the influence of test parameters (temperature, strain rate, and pressure) is the same for all propellants (11). Tensile tests are widely used to analyze propellant behavior as well as examine the manufacturing controls of the propellants. Because their behavior is not linear-elastic, it is necessary to define several parameters that allow a better representation of the experimental tensile curve. The stylistic experimental stress-strain response at a constant strain rate from a uniaxial tensile test is shown in Figure 7, where E is the elastic modulus (initial slope), Sr P is the tensile strength (used later for a failure criterion), and eXj> is the strain at tensile strength. 

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