Pure waterjet drilling thin CFRP laminate with [0/45/–45/90]2s stacking sequence.

High-pressure pure waterjet (WJ) technology is widely used in the hole drilling process for carbon fiber–reinforced polymers (CFRP) laminates because of its high processing efficiency and zero heat affected zones. However, the phenomena of the delamination zone and poor roundness pose significant challenges to the hole processing of CFRP laminates. In this study, the numerical and experimental investigation of a high-pressure pure WJ CFRP laminate drilling process are conducted, to improve the quality of the pure WJ drilling process. A comprehensive coupled fluid–solid numerical model based on the smoothed particle hydrodynamics method is developed to simulate the pure WJ drilling process of CFRP laminates and determine mechanism of the material removal. Thereafter, extensive pure WJ drilling experiments are conducted on two stacking sequence CFRP laminates to obtain a hole with remarkable roundness. The simulation results illustrate that during the WJ drilling of CFRP laminates, the material removal process and damage zones of each inter-laminate interface are mainly extended along the fiber direction (the direction of longitudinal Young's modulus). Water-wedging action is observed to play an important role in the damage of inter-laminate interface and propagation of peel-up and push-down delamination. Furthermore, the experimental results show that an increase in the WJ pressure contributes to the reduced hole taper and surface roughness of sidewalls. Holes with diameters below 2 mm are successfully drilled, and a roundness error of 0.05 mm is obtained for the [0/45/–45/90]_2s CFRP laminate, which is 1/6 of that of the [0]₁₆ laminate. [ABSTRACT FROM AUTHOR]