Investigation on the Continuous Wave Mode and the ms Pulse Mode Fiber Laser Drilling Mechanisms of the Carbon Fiber Reinforced Composite

Abstract

The near infrared (NIR) laser drilling of a carbon fiber reinforced polymer (CFRP) composite in the continuous wave (CW) mode and the ms pulse mode was investigated by an experiment and a numerical simulation. The relationships between the laser penetrating time, entrance hole diameter, surface heat affected zone (HAZ) width, and material ablation rate and the laser irradiation time and laser peak power densities were obtained from the experiment. For the same average power density of the laser output, 3.5 kW/cm2, it was found that the ms pulse laser mode, which had a higher peak power density, had a higher drilling efficiency. When drilling the same holes, the pulse laser mode, which had the highest peak power density of 49.8 kW/cm2, had the lowest drilling time of 0.23 s and had the smallest surface HAZ width of 0.54 mm. In addition, it was found that the laser penetrating time decreased sharply when the peak power density was higher than 23.4 kW/cm2. After analyzing the internal gas pressure by the numerical simulation, it was considered that a large internal gas pressure appeared, which resulted from polymer pyrolysis, causing a large amount of the mechanical erosion of the composite material to improve the drilling efficiency. Therefore, the ms pulse laser showed its potential and advantage in laser drilling the CFRP composite.

A Review of Research Progress on Machining Carbon Fiber-Reinforced Composites with Lasers

“…Freitag [ 74 ] optimized the pulse energy and the repetition rate of the pulsed laser to reduce the width of the HAZ and found that a high cutting quality can be obtained with a high pulse energy and high repetition rate at the same average laser power. Leone [ 75 ] cut CFRP with a Yb:YAG pulsed laser, and it was found that a better cutting quality was obtained with multi-channel technology at a higher scanning speed, and the width of HAZ can be reduced significantly. He also [ 69 ] used the Nd:YAG laser to cut CFRP and investigated the influence of process parameters on the geometry of the cutting slit and the HAZ at a speed of 12 mm/s.…”

Influence of hydrothermal ageing on CFRP single lap bonded joint pre-treated by laser texturing

“…[11][12][13][14] Instead, in the case of photochemical ablation, the energy of the photon is such as to break directly the molecular bonds reducing the HAZ extension. [15][16][17] Nevertheless, in the industrial field, CO 2 laser systems are widely used due to their flexibility, the power ranges adopted for different types of applications, wall-plug efficiency and better beam absorption behaviour. [18][19][20] Many studies have investigated the reliability of bonded joints in aggressive environments.…”

Experimental Investigation on Ablation Behaviors of CFRP Laminates in an Atmospheric Environment Irradiated by Continuous Wave Laser

“…At higher temperatures, the composite materials will turn into the process of sublimation. The complex response of composite to laser has a relation with some factors, including laser parameters [ 9 , 10 , 11 , 12 , 13 , 14 ], such as power density, spot size and irradiation time; characters themselves [ 13 ], such as fiber layup sequence and thickness; and environment conditions [ 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 ], such as vacuum, atmosphere environment and tangential flow.…”