Numerical analysis for stress fields induced by laser trepanning of square-slotted blind holes with and without ultrasonic assistance

•Simulation of stress fields for ultrasonic-assisted laser trepanning is reported.•Ultrasonic-assisted laser trepanning of square-slotted hole array is simulated.•Ultrasonic-induced transient and residual stress fields are numerically analyzed.•Transient stress field is different from corresponding residual stress field.•Ultrasonic assistance effectively relieves transient/residual stress on workpiece.