The study of the dissipation heat flow and the acoustic emission during the fatigue crack propagation in the metal

Abstract

This work is aimed at developing a thermodynamic approach to describing the propagation of fatigue cracks in metals. An attempt is made to explain the change in the character of heat dissipation at different stages of crack propagation: the nucleation, the Paris regime, the critical growth. The studies were conducted on two metal alloy: 304 AISE stainless steel and titanium alloy VT1-0. The investigation of the fatigue crack propagation was carried out on flat samples with stress concentrators. The stress concentrator was the triangular side notch. To monitor the dissipated thermal energy it was used method of infrared thermography and the contact heat flux sensor based on the Seebeck effect. Also the registration system of the acoustic emission was used for more exactly description of the fatigue crack propagation. Analysis of acoustic emission data on the basis of cluster analysis made it possible to classify various mechanisms of the damage process. A correlation was found between the integral dissipated thermal energy and the total energy of acoustic emission during the propagation of a fatigue crack. The joint application of these techniques has made it possible to reveal the moment's activation of failure mechanisms and their relationship to the dissipated heat flux.