Expansion Of Laser Peening Application With A High-Power Microchip Laser On A Robotic Arm

Laser peening (LP) introduces compressive residual stress (RS) onto the surface of metallic materials using nanosecond laser pulses irradiated through a water layer, thereby effectively suppressing fatigue crack initiation. However, conventional LP systems require large, stationary setups, restricting their use to indoor environments. To overcome this limitation, a portable LP device featuring a finger-sized microchip laser mounted on a collaborative robot arm has been developed. Equipped with a compact power supply and a water circulation/recovery system, the device can operate on-site with minimal setup. Successful processing across various materials has confirmed both compressive RS induction and fatigue life extension. Notably, the portable LP device can be used on members subjected to dead load (their own weight) after installation at construction sites. This helps to counteract tensile stress and enhance fatigue performance, as demonstrated by in situ LP experiments on HT780 fatigue samples.