This article is cited in 14 papers

Mechanical properties, strength physics and plasticity

Dynamics of microcracks and time dependences of surface deformation of a heterogeneous body (granite) under an impact

V. I. Vettegren, V. S. Kuksenko, I. P. Shcherbakov

Ioffe Institute, St. Petersburg

Abstract: The dynamics of fractoluminescence flashes and the time dependences of surface deformation of granite with different sizes of feldspar grains under an impact on samples by a metal pin have been studied with a 10 ns resolution. A band at $\sim$1.9 eV has been observed in the fractoluminescence spectra, which means that, under the influence of mechanical stresses, Si–O–Si bonds are broken and $\equiv$SiO$^\bullet$ free radicals are formed. The fractoluminescence has the form of flashes with a duration of $\sim$10 ns. It has been assumed that each of them corresponds to the nucleation of a microcrack. From the flash intensities and the elastic wave velocity, the linear size of microcracks has been estimated to be from $\sim$8 to 30 $\mu$m. Microcracks are mainly generated during passage of a deformation wave through feldspar grains. An impact causes the appearance of eigenvibrations of the entire sample, and cracking of grains gives rise to eigenvibrations of grains.

Received: 19.12.2011

 English version: Physics of the Solid State, 2012, 54:7, 1425–1429

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