Experimental study of heat generation at the vertex of a fatigue crack

The process of heat generation at the vertex of a fatigue crack in VT-6 titanium alloy under conditions of cyclic loading has been studied by infrared thermography. The spatial and temporal variations of temperature at the crack vertex have been measured, the shape of the zone of heat evolution has been determined, and the intensity of heat generation has been evaluated. Comparison of the obtained experimental data to the relations of the linear theory of elasticity shows that neither the observed shape of the plastic deformation zone nor the measured dynamics of heat evolution at the crack vertex is consistent with predictions of the linear theoretical models. The experimental results revealed a time delay between the moments of maximum applied stress and maximum intensity of heat evolution at the vertex of a fatigue crack.