Diagnostics of residual stresses in bimetallic aluminum–steel plates by means of laser ultrasound and a test hole

The character of changes in laser photoacoustic signals near small-diameter holes in layers of aluminum and steel in a bimetallic plate obtained by hot rolling is investigated. The experimental results are compared with the solution of the classical Kirsch problem for stress distribution around a circular hole in a prestressed material. The possibility of assessing internal stresses by a laser photoacoustics in combination with the hole drilling method in industrial bimetallic plates is shown.