Compression stress-strain response

Figure 6.14 shows the reload compressive stress-strain response of shock-loaded copper as a function of pulse duration [40]. For copper shock loaded to 10 GPa the yield strength is observed to increase with increasing pulse... 

Influence of temperature on the compressive stress-strain response of GUR 1050 (100 kCy, I 10°C). 

Stress-Strain Behavior of Polypropylene Both tensile and compressive stress-strain response of polypropylene is shown in Fig. 3.9. Quite obviously, the behavior in tension and compression are quite different for stresses above about 2,000 psi. This indicates that care must be used in analysis where the behavior in tension and compression are assumed to be the same. (See Rybicky and Kanninen (1973) for an example of the difference on the analysis of a beam in 3-point bending.)... 

The majority of tests to evaluate the characteristics of plastics are performed in tension or flexure hence, the compressive stress-strain behavior of many plastics is not well described. Generally, the behavior in compression is different from that in tension, but the stress-strain response in compression is usually close enough to that of tension so that possible differences can be neglected (Fig. 2-19). The compression modulus is not always reported, since defining a stress at... 

The stress-strain response of ideal networks under uniaxial compression or extension is characterized as follows ... 

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. 

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) ... 

Flat-wise compression was performed on an MTS QTEST/150 electromechanical frame outfitted with a moveable furnace as per the ASTM C 365 standard. Stress-strain responses... 

Figure 3.10 Stress-strain response of the pure SMP and syntactic foam at room temperature. The SEM images show the microstructure of the foam at compressive stain levels of 5, 30, and 60%. A progressive breaking of the microspheres occurs as the strain level is increased. Source [41] Reproduced with permission from Elsevier...

The model of Hess and Barrett was qualitative a few years later Frank and Stroh [135] proposed a more quantitative model in which they considered the energetics of the process that is the starting point for the microscale model (as discussed in the next section) that is currently used to qualitatively and quantitatively explain the typical response of the MAX phases to cyclic compressive and tensile stresses at room temperature (Figure 7.12). In Figure 7.12a are plotted typical cyclic compressive stress-strain curves for Ti3SiC2 with two different grain sizes. Also... 

D3410-87 Compressive properties of unidirectional or crossply fibre resin composites D3518-91 In-plane shear stress-strain response of unidirectional reinforced plastics D3846-79 In-plane shear strength of reinforced plastics... 

When a material is subjected to cyclic loading, its stress-strain response may change with the number of applied cycles. If the maximum stress increases with the number of cycles, the material is said to cyclically harden . If maximum stress decreases over the number of cycles, the material is said to cyclically soften . If the maximum-stress level does not change, the material is said to be cyclically stable . As seen in Fig. 7.33, the nature of these transformation-induced hysteresis loops is cyclically stable when the stress level is considered. However, the strain of these cycles upon unloading and under compression are different, possibly due to the asymmetric stress characteristic of phase transformation (the peak strain at compression point E is less than that at tension point B). 

Tervoort and co-workers Model. While the above models make reasonable predictions of the stress-strain behavior in monotonic loading conditions, a main drawback to them is that they use only a single stress-dependent characteristic (relaxation) time. As a consequence, the predicted behavior tends to show a sharp transition between elastic (solid-Hke) and plastic (fluid-like) behavior. However, it is found in practice that all poljnners exhibit behavior consistent with a spectrum of relaxation times and this is clearly going to affect the stress-strain response at constant strain rate. In an effort to address this inconsistency Tervoort and co-workers (40) have developed a modified compressible Leonov model. ... 

The challenges inherent in the measurement of stress-strain response of thin film materials by means of direct tensile testing are commonly more than offset by the distinct advantage that properties characterizing deformation resistance of the material in the plastic range can be determined under isothermal conditions for a relatively simple state of stress on the specimen. However, these techniques are not readily amenable to modifications that can accommodate uniaxial compression, simple shear stress, equi-biaxial stress or states stress on the specimen. As a result, it is difficult to draw conclusions concerning the dependence of plastic response on stress path history. It is noted that results for some cyclic tension-compression experiments were reported by Hommel et al. (1999). 

There are two types of elastic moduli. First, there is the static elastic modulus that is measured from the stress-strain response of the solder when subjected to tension or compression testing (Ref 25). The second type is referred to as the dynamic elastic modulus and is measured by the passage of sound waves through the material (Ref 26). In the latter case, because sound wave propagation in a solid is based upon atomic vibrations that are very rapid, inelastic deformation is largely ehminated from the material response. Therefore, the modulus is determined from nearly pure elastic deformation. On the other hand, the static modulus is sometimes preferred when calculating plastic strain because it accounts for aU deformation leading up to the yield stress as defined by the 0.2% offset criterion. 

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