Cyclic loading-unloading

The deformation and strength properties of Jinping marble with different confining pressures under cyclic loading—unloading tests... 

Figure 6. The complete stress-strain curve of cyclic loading— unloading tests under different confining pressures.

Component stress—during the back flow and forward reversals, all liic components involved with the gas propulsion are loaded diui unloaded, placing blading in a cyclic loading mode. 

Fig. 4.41. Schematic drawings of loading and unloading processes measuring the relative displacements 5 and 6, in (a) fiber pull-out and (b) fiber push-out models under cyclic loading. After Zhou et al. (1993).

After completion of DHC test specimen has been unloaded and cooled down in the furnace to the room temperature. Specimen then has been subjected to cyclic loading to outline the DHC crack and then fractured. After completion of DHC test actual crack length was measured from fractographs (Fig. 2). 

Of particular note is the importance of erosion in accelerating tooth wear. The softening of enamel and dentine surfaces by erosive attacks from acid renders the surface extremely susceptible to mechanical attacks [9]. Abfraction is also an example of interaction between wear mechanisms, where abrasion and erosion may act in combination with cyclic loading and unloading to produce an overall wear effect. 

Since the seals were going to be exposed to very large hydrostatic pressures, a set of hydrostatic pressure tests of loading followed by unloading were also performed. The results from these tests indicated that the volumetric response of the material also included volumetric hysteresis during cyclic loading. One example of the volumetric response is shown in Fig. 11.15. 

Fig. 30. (a) Load-displacement and (b) ACP vs relative contact depth curves for Ge obtained in cyclic nanoindentation at the loading/unloading rate of 1 mN/s. Arrows indicate the loading direction. After Reference [38]. 

Conditions where the pipe is under cyclic loads may result in increased crack growth rates. Operating pressures for a large-diameter pipe can measure up to 8700 kPa (1250 psi). The pipeline pressure continually fluctuates due to loadiug aud unloading of product and is influenced by pump activity. This applies to both gas and liquid hues but has greater influence in liquid systems [6]. 

Phase 2 consisted of a series of load-unload cycles conducted at the same rate as in Phase 1, but taken to progressively higher nominal strains Cmax on each cycle 1,2, 3. Between 3 and 5 cycles were possible before failure with most materials. These may be described as pseudo-cyclic experiments, to distinguish them from those in Phase 1 where the maximum strain was constant. As in Phase 1, for each... 

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