Shake down effect

At low levels of loading creep effects are small and are normally recoverable, although material shake down effects should be recognised. 

Fig. 3.50 Schematic of shake-down effect. Test piece subjected to cyclic bending a outermost metal fibers from neutral axis exceed yield strength, b upon unloading fibers that exceeded yield strength remain in either compressive or traction stress state, depending on whether during the loading phase they exceeded yield in traction or compression...

Fig. 3.53 Effect of prestressing on a plate a with small hole and b with large hole. In the former case the shake-down effect is fully developed, in the latter it is not...

It is also evident that the shake-down effect has produced a decrease of the mean stress acting on this new material that will not be any more but a < [Pg.290]

It is indeed worth to recall that the shake-down effect is possible only when the plastic volume is confined and very small with respect to the elastic one that has to control the process. This is the case of a thin beam in bending or a small hole or a sharp discontinuity whose associate plastic zone is embedded in the elastic surrounding and remains negligible. But when the plastic volume enlarges, as in a thick beam in bending or a large hole, the shake-down effect may not take place completely. Depending on the ratio of the plastic zone volume to... 

Fig. 5.42 Schematic of Shake-down effect in an elastic-ideally plastic material subjected to cyclic stress amplitude and mean stress

Fig. 5.43 Shake-down effect on the mean stress and allowable stress amplitude

The shake-down proeesses in the eourse of photoemission from Ce" cations determine the shape of spectrum as well-resolved multiple structure (Fig. 72). For composites annealed at different temperatures, the gaps between neighboring peaks somewhat differ, which is caused by the varying eontent of Ce eations [143]. A slight difference observed between spectra of composite sintered at increasing temperatures indicates that this content is rather small to cause any substantial effect. 

Core electron ejection normally yields only one primary final state (aside from shake-up and shake-off states). However, if there are unpaired valence electrons, more than one final state can be formed because exchange interaction affects the spin-up and spin-down electrons differently. If a core s electron is ejected, two final states are formed. If a core electron of higher angular momentum, such as a 2p electron, is ejected, a large number of multiplet states can result. In this case it is difficult to resolve the separate states, and the usual effect of unpaired valence electrons is... 

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