Laser processing of carbon fibre reinforced plastic (CFRP)

Student thesis: Doctoral Thesis

Abstract

Carbon fibre reinforced plastic (CFRP) is extensively used in automotive and aerospace industries with the aim to achieve reduction on emission by reducing weight and consequently fuel usage. Due to high demand and governmental regulations to reduce the environmental impact, the need for re-using CFRP is becoming an interesting area of application with economic benefits to industry. Cutting CFRP to meet large manufacturing demands with fast cutting speeds and high-quality cuts can impose significant problems for conventional cutting methods. High power lasers can provide fast and efficient cutting speed, but if not controlled effectively can cause excessive fibre damage that has significant impact on the mechanical strength. Secondly, the joining technology is one of the major obstacles in composite parts application. Traditional joining techniques such as screwing and riveting damage the fibres, leading to major stresses due to drilled holes. One way to achieve higher degree of material application is to use adhesive bonding between two surfaces. However, a good adhesion between two surfaces is necessary to achieve strong and high resistance bonds. A surface pre-treatment is essential before the adhesive bonding to bring reproducibility a clean, slightly rough, and preferably active surface. One of the approaches is to use laser as a method of cleaning. Currently lasers are only used to clean the surface of virgin material for surface contamination. This thesis presents a research work using a 1.5 kW single mode fibre laser to investigate the effects of process parameters such as cutting speed, multi-pass, stand-off, large diameter aperture, double aperture and trenching on the reduction of fibre damage to under 100 μm. The fibre damage was observed using scanning electron microscope. Thermal cameras were used to observe the temperature throughout the cutting process. Regression analysis was carried out to develop five models for CAD/CAM interface for quick adaptation of the laser cutting process - in addition, contour plots have been developed for analysis of process parameters on the fibre damage. For laser cleaning a novel approach was used that employs a flash pumped Nd:YAG laser to clean the glue remained on separated CFRP parts, previously joined with PU and EP adhesive with the aim to reduce the CFRP waste by limiting the damage fibre and composite material substrate as a whole and for re-joining purposes. A feasibility study was conducted to assess the developed laser cleaning process in removing adhesive residue from internal curvatures of 3D CFRP components.
Date of Award29 Sep 2021
Original languageEnglish
Awarding Institution
  • University Of Strathclyde
SponsorsUniversity of Strathclyde & EPSRC (Engineering and Physical Sciences Research Council)
SupervisorPaul Xirouchakis (Supervisor) & William Ion (Supervisor)

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