Stress-elongation curve

Fig. 17. The stress-elongation curve obtained from Nitinol by applying a uniaxial tensile load at temperature below the TTR. The portion of the curve, 0 - A represents the zone of easy plastic flow. A - B illustrates elastic recovery, and B - 0 is recovery (contraction) possible by heating to above the TTR. - reference [49]...

Experimental estimates of p and // usually must rely on a model for the crosslinking chemistry, making quantitative tests of the phantom model difficult. Network defects preclude the use of Eqs (7.31) and (7.41), written in terms of the molar mass of a network strand M. Indeed, since Ms is not known for real networks and the affine and phantom models predict the same classical form of the stress-elongation curve [Eqs (7.32) and (7.33)] there is no practical means of determining which (if either) model is correct for small deformations of unentangled networks. For these reasons, we henceforth describe the modulus of all classical models as a network of strands with apparent molar mass M ... 

Fig. 2. Stress-elongation curves at various rates of elongation75). Compound 1403-1...

Fig. 3. Stress-elongation curves after prestrain to 200% at various speeds and at reduced temperature75. Compound 1503-5, T = 5 °C...

Figure 18.15 Stress-elongation curves of in situ silica and commercial silica-filled NR vulcanizates ( NR-71Si NR-71 referring to 71 phr of in situ silica-filled NR and - NR-71VN NR-71 referring to 71 phr of commercial silica-filled NR vulcanizates.

The mechanical behavior of materials under stress can be graphically illustrated by macroscopically determined stress-elongation curves and characterized by typical values of moduli, strength, yield stress, strain, toughness, and others. Different types of stress-strain curves are schematically shown in Figure 3, which are connected with different groups of micromechanicai processes. 

Fig. 3. Characteristic types of stress-elongation curves of polymers. See text for a description of types a-e indicated in the figure.

A variety of specimen shapes and sizes can be used but the most common is a smooth-bar tensile coupon, as described in ASTM E 8, Test Method for Tension Testing of Metallic Materials." In smooth-bar tests, the changes are measured in terms of time to failure, ductility (elongation or reduction-in-area), maximum load achieved, and area bounded by a nominal stress-elongation curve or a true stress/ true strain curve, which are often supported by fractogra-phic examination. The specimen is exposed to the environment while it is stressed under a constant displacement rate. 

Figure 11.2 Comparison of the nominal stress-elongation curve (load-elongation curve) and the true stress-elongation curve...

Fig. 90. The temperature dependence of the nominal tensile stress-elongation curves of amorphous Mgg CU Y,5 sheets with a thickness of 0.5 mm and a width of 3 mm.

Fig. 102. Tensile stress-elongation curves of the melt-spun MggjZnijCej alloys in as-quenched and annealed...

Fig. 140. Tensile stress-elongation curve at room temperature for a 3 mm diameter cylinder of amorphous La jAl2gCu, jNt3 7jCo3 75.

Fig. 8.1 Stress-elongation curve for natural rubber in the vicinity of room temperature. (From Mark (5))...

Figure 9.12 Typical stress/elongation curve for a rubber compound in tension.

Conformable Film Tapes. For many applications the tape should conform to a rugged or profiled surface. There are two types of films, which differ in their tensile stress elongation curve. 

Fig. 2. A typical nominal stress-elongation curve corresponding schematics of deformed specimen during tensile deformation.

Figure 6.2 Stress-elongation curve for an elastomer showing an upturn in modulus at high elongations.

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