Влияние Механических Напряжений На Поведение Лазерных Ультразвуковых Сигналов Вблизи Отверстия В Керамике Нитрида Кремния

Abstract

An experimental study of the behavior of laser ultrasonic signals near a hole in a plate from dielectric silicon nitride ceramics under the action of external compressive stresses is carried out. A fundamental discrepancy between the results obtained and similar results obtained by us earlier for metals and a quantitative discrepancy with the predicted thermodynamic model of the formation of thermoelastic signals from stressed materials is shown. An explanation of the observed discrepancies is proposed using the model of thermal excitation of lattice defect states that we proposed earlier.