Study of Residual Stress on the Copper Plate Using Laser Ultrasound Technique

During the manufacturing process, residual stress exists inside the material. It reduces fatigue strength and causes material cracks. The study of residual stress helps to confirm its structural quality and can avoid unnecessary damage to the material. In the present study, the laser ultrasound technique (LUT) generates the Lamb wave, which propagates inside the material. Depending on the value of residual stress, the wave velocity changes and is received by the transducer. Then, the experimental results were compared with the inversion results. The results showed that Young’s modulus decreased while increasing the stress.