Effects of crack surface roughness on crack heat generation characteristics of ultrasonic infrared thermography

Abstract This study examined the effect of the fatigue crack contact roughness on the thermal characteristics of ultrasonic infrared thermography. Fatigue cracks were prepared on grade 45 steel samples; the crack surface roughness was tested, and ultrasonic infrared thermography experiments were carried out. The results showed that a rougher crack surface caused the fatigue crack to generate more heat. Combined with the finite element simulation results, the frictional force was concluded to determine the heat generation by a crack under ultrasonic excitation. Differences in the crack surface roughness change the friction coefficient, which affects the contact force of the crack surface and in turn affects the heat generation.