Optimization of Ti-GFRP Laser Joining Process to Achieve Superior Mechanical Performance for the Overlap Configuration

Laser joining of GFRP (nylon 66–30% glass fiber reinforced) to titanium is a promising method that can reduce product weight and enable multi-material development feasibly in miscellaneous industries such as aerospace. However, this joining is challenging due to the mismatch of their chemical and physical properties. Thermal degradation of the polymeric material due to the high energy input of the laser beam and the lack of proper adhesion are common defects in overlap configuration which can reduce the mechanical strength and permeability. To address the former, a structured and controlled manner design of experiments (DoE) is applied for statistical analysis to gather the optimized parameters of the joining. Studying a range of laser power, laser scanning velocity, and beam oscillation of laser beam shows there is a threshold that can affect and improve the joining quality and mechanical strength. To resolve the latter, laser surface treatment of the Ti prior to the laser joining process, which is a precise and non-contact procedure, is applied to strengthen the bonding. Microscopic observation and mechanical tensile-shear tests are used for analysis of the joints and mechanical strength measurement.