Features of the behavior of laser ultrasonic signals near a hole in duralumin when exposed to two misaligned mechanical stresses

The effect of misaligned mechanical stresses on the excitation of ultrasonic vibrations by focused laser radiation near a small-diameter hole in aluminum alloy is investigated. The analysis of the behavior of the signal at various mutual angles and values of two uniaxial stresses is carried out. It is shown that at certain angles under the action of mechanical stresses, not only the contrast of laser ultrasound images changes, but also their rotation as a whole relative to the center of the hole can occur. The possibility of disappearance of the linear component of laser ultrasonic signals at certain characteristics of stress and appearance of a nonlinear component is also demonstrated.