Advanced micro-welding strategies with pulsed Nd:YAG lasers

Thermomechanical Modeling of Laser Spot Welded Solar Absorbers

“…The absorbed radiation is converted to heat, which has to be transferred with high effi ciency to the fluid carried by the pipeline. LSW has been increas ingly utilized in the manufacturing process of thermal solar absorbers to join tubes with a flat-sheet absorbing surface [4], LSW offers high flexibility in the manufacturing process and allows for the development of high heat transfer rates from the absorbing surface to the tubes [4], Compared to conventional welding methods, laser welding pro vides a minimum amount of concentrated thermal energy transfer to components, which leads to smaller heat affected zones (HAZs) and lower distortions [5]. When joining of dissimilar materials is involved, as is the case in the manufacturing of Al-Cu flat-plate solar absorbers, the factors that mainly affect the development of residual stresses and deformations are the differences among ther mophysical properties and mechanical properties of the materials being joined (Al-Cu) and the material of the weld joint (mixture of Al-Cu) [6,7], In operation mode, solar absorbers are exposed to daily thermal cycles with temperature differences approaching 70-80 °C, and the fluid flow in the pipeline causes a temperature gradient between the pipes and the sheet absorbing surface.…”