Paper Title
Investigation on The use of Power Ultrasonic to Improve the Laser Welding of Aluminium Alloys

There is a rising interest on the autonomous laser welding of Aluminium alloys due to the quality of the weld, productivity and the simplicity of implementation. Unlike high grade alloys (i.e. Al 1100 which has excellent weldability), laser welding of low grade Alloys (i.e. Al 6063 which has poor weldability) has a higher demand due to material strength and cost benefits. However, laser welding of Alloys such as Al 6063 are challenging due to the material composition which has a poor weldability. Current study investigates the possibility of using high power ultrasonic during the laser welding process, to reduce voids during solidification and optimize the laser welding process. A finite element-based numerical study was undertaken to evaluate the propagation of ultrasonic waves and their interaction with the incremental weld seam. The plate sample (before joining) used in this study is a 300 x 150 x 3 mm (height, width and thickness respectively). A parametric study was conducted to obtain the resonant frequency of the sample plate and the optimum power level in order to tune the power ultrasonic system. A 3-D laser Doppler vibrometry experiment was conducted to validate the finite element results. There is a good agreement between numerical and experimental results. Based on the results, 40 kHz 60 W transducers need to be used for ultrasonication in order to improve the laser welding of Al 6063 using power ultrasonic. Furthermore, transducer topology was also investigated in order to optimize the system performance. Keywords- Manufacturing optimization, laser welding, power ultrasonic, solidification, Aluminium alloys, porosities