Stress/strain dynamic

From the results obtained when used in a dynamic stress-strain mode, a hysteresis graph can be generated. As the machines were developed and computerized results obtained, a new group of instruments was developed, namely, the dynamic mechanical analyzers. 

It is important to note that stress softening is also present during dynamic stress-strain cycles of filled rubbers at small and medium strain. In particular, this can be concluded from the dynamic mechanical data of the S-SBR samples filled with 60 phr N 220 as shown in Fig. 48. In the framework of the above model, the observed shift of the center point of the cycles to smaller stress values with increasing strain amplitude or maximum strain and the accompanied drop of the slope of the hysteresis cycles can be related to a de-... 

Fig. 48 Dynamic stress-strain cycles obtained from uniaxial harmonic excitations at 1 Hz of the S-SBR samples filled with 60 phr N 220 at fixed pre-strain and various strain amplitudes, as indicated...

For a stress amplitude of 17.2 MPa, Fig. 7 showed the changes that occur in the dynamic stress-strain response of HIPS at various N values. By monitoring such hysteresis loops, one can determine the specific dependence on N of properties such as the secant modulus Or one can detect onset ot strain softening by measuring the width of the hysteresis loop, taken at a given value of the tension or compression stress, and note how this changes with N. Such a plot is shown in Fig. 11 for a HIPS sample that fractured at 202 cycles. 

In addition, other measurement techniques in the linear viscoelastic range, such as stress relaxation, as well as static tests that determine the modulus are also useful to characterize gels. For food applications, tests that deal with failure, such as the dynamic stress/strain sweep to detect the critical properties at structure failure, the torsional gelometer, and the vane yield stress test that encompasses both small and large strains are very useful. 

Deformability and Wet Mass Rheology The static yield stress of wet compacts has previously been reported in Fig. 21-113. However, the dependence of interparticle forces on shear rate clearly impacts wet mass rheology and therefore deformabihty. Figure 21-117 illustrates the dynamic stress-strain response of compacts, demonstrating that the peak flow or yield stress increases proportionally with compression velocity [Iveson et al., Powder Technol., 127, 149 (2002)]. Peak flow stress of wet unsaturated compacts (initially pendular state) can be seen to also increase with Ca as follows (Fig. 21-118) ... 

Dynamic stress-strain curve of anthracite coal and limestone... 

The dynamic stress-strain curve of specimen was obtained through (1), (2), (3) formula. The stress-strain curve of specimen is shown in Fig.6. 

Figure 6. (a) Dynamic stress strain curve of anthracite (b) Dynamic stress strain curve of limestone. 

The incident and reflected waves obtained with X-SiOx samples are shown in Figure 22.14A as a function of time. The positive portion indicates compressive waves and the negative portion denotes tensile waves. The transmitted wave is shown as the output signal. In an SHPB test, a dynamic equilibrium state, indicated by equal stresses applied on both ends of the specimen, must first be established. Such an experiment is then considered valid and the acquired experimental data are processed to deduce the dynamic stress-strain relationships. To examine the dynamic equilibrium condition, following either the first-wave (transmitted wave) or the second-wave (difference between incident wave and reflected wave) method [26, 66, 73], the front stress (at the end of the specimen in contact... 

Figure 22.15. Dynamic stress-strain curves of X-aerogels with various high strain rates A. X-SiOx with density...

Fig. 10 Output data from the nonresonance forced vibration method. (A) Relationship between sinusoidal force and deformation for a viscoelastic body. (B) Dynamic stress-strain hysteresis loop for a viscoelastic body.

Dynamic stress-strain curves under compression at different strain rates, case of cold cured adhesive (From Gogiio et ai. [2008], copyright Elsevier)... 

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