Thermo-mechanical simulation of friction spot joining of aluminum alloys to short glass fiber-reinforced PPS

The influence of process parameters of friction spot joining (FSpJ), of aluminum alloy AA5052 and short glass fiber-reinforced polyphenylene sulfide (GF-PPS) sheets, was studied on the temperature distribution and bonding strength of joints through experiment and computer simulation. Numerical simulation pro-vides an invaluable in-depth understanding of the FSpJ process and joint characteristics, which is difficult if not impossible to obtain through experiment. Three-dimensional (3D) finite element models were built based on the geometry of actual joints, calibrated using experimental data, and verified by experiments. This study shows that in the bonding area temperature is the highest at the center in front of the spinning pin during FSpJ, and it can easily reach a value higher than the melting temperature of GF-PPS, but lower than its decomposition temperature in all the joints with reasonable strength. Increasing rotational speed and plunge depth raises the temperature, and enlarges the bonding region. It was found that simulation and experiment produce very similar temperature profiles and peak temperatures; the highest temperature measured was 428 celcius, and the margin of error between the simulated values and experimental observations was below 15%. Cracks were found largely curved, mainly distributed along the edges of the bonding region in the GF-PPS base material. It was also found that the structural characteristics of the plastic deformation zone and bonding zone of a joint have significant impact on the bonding strength. A joint's strength cor-relates positively with the plastic and bonding zone sizes, with the bonding zone size playing a larger role. Finite element simulation provides an opportunity to quantify and optimize the FSpJ process and joint strength (c) 2023 CIRP.