Cyclic typical compressive

Figure 7.12 Typical compressive cyclic stress-strain curves, (a) Fine-grained and coarse-grained Ti3SiC2. The dotted line is a linear elastic response expected forTi3SiC2 had kinking not occurred. Also included are the results on AI2O3 and Al for comparison [5] ...

Additional factors which must be taken into account are environmental effects (thermal as well as chemical), effects of defects, statistical variability of the material, long-term behavior, and cyclic versus static loading effects. Assessment of these effects requires the end user to conduct a large series of tests using multiple specimens. A typical series will examine a unidirectional material in tension in the 0, 90, and cross-ply directions 0, 90, and cross-ply in compression and 1-2, 1-3, and 2-3 shear at different temperatures ranging from —54°C to the expected service temperature creep rupture at temperatures up to the expected service temperature and fatigue at room and elevated temperature. This series of tests, shown in Table 12.1, may require over 400 specimens. 

Peristaltic Pumps, Fig. 2 A typical macroscale linear peristaltic pump design. A set of translating actuators cyclically compresses a flexible tube. The number of actuators may vary. Features of macroscale rotating... 

Figure 7.21 Typical creep curves under triaxial cyclic compression.

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... 

An important issue is the influence of an electrochemical environment on the cyclic deformation behavior of metals [74,33-35]. As illustrated by the data in Fig. 1 for a carbon-manganese steel in high-temperature water, environment does not typically affect the relationship between stresses and strains derived from the maximum tensile (or compressive) points of steady-state (saturation) hysteresis loops [36]. Such loops should relate to elastic and plastic deformation prior to substantial CF microcracking. CF data of the sort shown in Fig, 1 are produced by either stress or total strain controlled uniaxial fatigue experiments, identical to the methods... 

Cyclic behavior in fiber composite plastics is determined by tensile/compressive-swell or by cyclic flexural tests. While normal stress or also deformation can be kept constant for tensile/compressive swell tests, in cyclic flexural tests a flexural strain is typically set and the damage state defined by a certain stress reduction. 

A series of cyclic simple shear (CDSS) tests on typical sand materials at a range of initial density and stress level, with the post liquefaction consolidation settlement monitored. This will give a combined elastic and plastic compressibility. 

Typically, beams or columns with low axial compression exhibit predominantly tensile yielding. Therefore, the monotonic curve provides a reasonable envelope to the cyclic response in the tension range, while compressive behavior deviates. In columns with high compression stress levels and high confinement ratios, reinforcing bars may be subject to strain reversals of almost equal magnitude. In that case the stress level for a given strain may substantially exceed the stress indicated by the monotonic behavior (Priestley et al. 1996). 

FEA material models are typically based on this tensile data but only one curve is allowed. The first cycle data is termed non-cyclic data since it does not take the cyclic softening into account. The fifth cycle data is termed the cyclic data as it represents the conditioned material in its equilibrium state. Clearly the first and the fifth cycle data exhibit different mechanical behavior and a single material model would not capture both responses. This cyclic material testing is repeated for compression and shear in order to have a complete database based on cyclic testing in all deformation modes. 

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