Investigation of the dynamics of failure of individual structural elements by the optical polarization method

The article presents the results of the investigation of the state of stress and the kinetics of an internal crack in plates of epoxy resin ÉD-20 MTGFA with a central circular and elliptical hole under the effect of a tensile pulse. It was established that the crack growth is of pulsating nature consisting in alternating slowing down and speeding up of its motion. It is shown that the jumpwise motion of the crack is accompanied by a smooth change of the stress intensity factor (SIF). Diagrams of the change of crack growth rate and SIF vs. time are plotted. The process of failure of specimens with circular and elliptical hole is described.Translated from Problemy Prochnosti, No. 9, pp. 46–48, September, 1991.