Abstract: Titanium alloy rivets tend to become uneven and crack easily when deformed. Pulse current is therefore introduced in the riveting process of the Carbon Fibre-Reinforced Polymer (CFRP) to soften the rivets and improve their plasticity. The thermal response mechanism and temperature field distribution in the connection domain are studied. A static Joule heating model is constructed based on the conservation of energy, Joule's heat law, and the law of heat conduction to characterize the CFRP temperature under steady-state heat exchange riveting conditions. Considering the current fluctuation and the uneven temperature distribution during riveting and the dispersion of the hot zone, we establish a dynamic temperature field model to predict the temperature rise during the riveting process. The results show that the temperature within a certain radiation radius around the CFRP hole is linearly related to that of the nail center, and the model accurately simulates the process temperature within 40 s. The static model accurately predicted the central saturation temperature within an error of 11%, and the trend of temperature rise simulated by the dynamic model was in good agreement with the measured temperature value. The hysteresis of heat transfer leads to an error of the dynamic model in temperature prediction during rapid temperature rise. The error increases with the rising of the current density, and the maximum value reaches 17.15%. The joint damage assessment reveals that qualified riveted joints can be obtained when the process temperature is controlled within 150℃.

Key words: rivets, current assistance, thermal response, modeling, Carbon Fibre-Reinforced Polymer (CFRP)