Research on Reducing Drilling Damage of CFRP Pipe Based on Plastic Pipe Auxiliary Support

Carbon Fiber Reinforced Polymer(CFRP) pipes are prone to damage (delamination, burrs, and tears) during the drilling process. This study analyzes the critical conditions for delamination at the drilling entrance and exit based on the initial stress of deformed fibers in CFRP pipes. On this basis, four drilling experiments were designed, namely without auxiliary support, with auxiliary support inside the pipe, with auxiliary support outside the pipe, and with auxiliary support inside and outside the pipe. The auxiliary support parts are plastic pipes. In the absence of support, both theoretical analysis and experimental results indicate that concave drilling exits are more prone to delamination compared to convex drilling. Compared to the situation where there is no support, the delamination factors of the supported convex drilling and concave drilling hole exit are reduced by an average of 18.7% and 12.6%, respectively. This indicates that using plastic pipes as internal and external supports during CFRP pipes drilling process can significantly reduce exit damage and improve drilling quality.