Specifics in longitudinal wave packets behavior in the sample middle section during its stepwise tension

Synergistic emission process based on the material dislocations is ensured by two mechanisms, i.e. energy pumping into the metal dislocation structures and combined release of this energy portion in the form of a powerful acoustic emission. One of the options in implementing this process is performed by the sample small-step loading. This type of load makes it possible to implement two processes simultaneously: one group of dislocations is charged with the energy transferring it to the extremely excited state, and the other group of dislocations reaches the energy threshold, appears on the metal crystalline structure surface and emits an acoustic signal. As a result, a powerful synchronous periodic emission wave is formed characterizing the metal crystal stress-strain state at the nano-level. The emission radiation synchronicity is ensured by another wave, i.e. the deformation wave arising during the sample stretching and propagating along this sample. The wave propagates repeatedly along the sample and forms a complex stress structure in its cross-section. This structure is important, because it determines the emission signal intensity. To identify characteristics of the load flowing from this process wave part over time under the multi-stage loading, a mathematical model was introduced. Software developed on its basis makes it possible to evaluate behavior of the repeatedly appearing group of such waves in the sample cross-section under consideration. The specified software assisted in a numerical experiment to study the wave load alteration in the sample middle section with its stepwise increase. Analysis of the experiment results showed that varying the sample loading tachogram type makes it possible to change the wave load in it to achieve its desired form over a certain time period. The selected mode of load alteration in the sample cross-section under consideration makes it possible to control the shape of the emission signal arising in this case.

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