Surface morphologies and subsurface damage characteristics of plain-woven CFRP composite in UV laser multi-passes scanning
Jinxuan Bai, Hou Yuze, Haiqing Zhu, Linmao Qian
Abstract
Plain-woven carbon fiber reinforced polymer (CFRP) is extensively utilized in the manufacturing of aircraft wings, engines, and wind turbine blades. Prolonged operations under extreme conditions will lead to surface defects, including pits, cracks, delamination, and scratches. It is essential to accurately remove the damaged substrates and prepare for subsequent component repairs. However, the structural complexities of plain-woven CFRP, along with natural heterogeneity and anisotropy, present considerable obstacles in achieving high machining performance. In this study, ultraviolet (UV) laser processing of plain-woven CFRP was conducted adopting a nanosecond pulsed laser, focusing on demonstrating the influence of laser ablation conditions (power, speed, laser beam direction) on surface appearance, heat-affected zone (HAZ) width, area, kerf structure (width, depth), taper angle, together with parting plane morphology. Additionally, material porosity was determined for subsurface damage obtained from industry X-ray computed tomography (CT) using a critical defect regularization way. By systematically conducting tests across a broad process range, a relationship between the HAZ and the kerf structure, as well as process parameters, was revealed. Results showed that while an inclined laser beam direction would improve cut surface performance significantly, it resulted in notable subsurface damages and cracks. Finally, high-integrity partition zones without visible fiber pull-out or delamination phenomena were gained when particular laser scanning condition combinations were applied. Clarifying these above aspects provides an important reference for the high-performance machining of plain-woven CFRP.