Study on interface temperature control of laser direct joining of CFRTP and aluminum alloy based on staged laser path planning

Because of the heating lag and heat accumulation during the laser direct joining process of carbon fiber reinforced thermoplastic composite and aluminum alloy, the interface temperature is non-uniform and difficult to control. To resolve this issue, a novel interface temperature control method characterized by staged laser path planning is proposed. The maximum temperature that the workpiece has experienced and will experience is used as the basis for path planning. Subsequently, constrained by the melting and decomposition temperatures of the thermoplastic composite, a reciprocating laser path with adjustable reversing positions is planned to preheat the initial joining area. For the subsequent area, an adaptive fusing path is obtained by analyzing the relationship between the interface temperature distribution and the set temperature conditions. The results of validation experiment suggest that the temperature control method is suitable for various geometries, and it also ensures that the interface temperature difference consistently remains within 80 celcius, which is significantly lower than the temperature difference of hundreds of degrees Celsius under the path, where the influences of heat accumulation and thermal boundary conditions on the joining temperature is not considered.