Research On Laser By Layering Paint Removal And Real-Time Monitoring Of Carbon Fiber Reinforced Polymer

Carbon fiber reinforced polymer(CFRP)have the advantages of high specific strength,lightweight and good fatigue resistance,and are widely used in aerospace,rail transit and military equipment.Aiming at the application requirements of precision removal of multi-layer paint(including primer and topcoat)on the surface of carbon fiber Reinforced Plastic and meeting the requirements of environmental protection,safety,efficiency and maneuverability,the laser layered paint removal technology is studied to solve the problems of large environmental pollution,high labor intensity and unsatisfactory paint removal effect of traditional paint removal technology.In this paper,by analyzing the physical parameter characteristics of polyurethane topcoat,epoxy resin primer and carbon fiber composite substrate,a high-speed camera system is built to capture the dynamic process of laser paint removal,and the action mechanism of laser removal of different paint materials is obtained combined with thermodynamic theory;Moreover,the on-line detection method of laser layered paint removal quality is proposed,and a large number of laser plasma spectral lines of different coatings are obtained.Combined with the analysis of surface micro morphology and element composition,the characteristic element spectral lines are found,and the partial least squares discriminant analysis(PLS-DA)model is established to successfully judge the quality of laser layered paint removal;The influence of laser process parameters on the effect of layered paint removal is experimentally studied.The effect of laser paint removal is evaluated by surface morphology and performance,and the best process parameters of laser layered paint removal are obtained,which provides a technical reference for the application of laser paint removal of carbon fiber reinforced polymer.The specific research contents are as follows:(1)According to the analysis of the physical characteristics of the topcoat,primer and carbon fiber composite substrate,the thermal ablation and thermal stress mechanism of laser paint removal are described,which lays the theoretical foundation of laser layered paint removal.The laser layered paint removal mechanism is experimentally studied.A high-speed camera system is designed to collect the dynamic process image of laser paint removal,and a high-speed visualization system is constructed.The laser layered paint removal mechanism of polyurethane topcoat or epoxy resin primer and simultaneous paint removal mechanism are obtained by combining theory and experiment.The results show that the laser energy density and material properties determine the main mechanism of laser paint removal.Compared with the simultaneous removal of topcoat and primer by high-energy laser,laser layered paint removal has less thermal damage to carbon fiber composites.In theory,laser layered paint removal technology has higher application advantages.(2)An on-line detection method of laser layered paint removal quality based on laser-induced breakdown spectroscopy and partial least squares discriminant analysis is proposed.Through the analysis of surface micro morphology and element composition,it is found that the laser-induced spectral lines of Al and Cr elements unique to the primer can effectively evaluate the effect of layered paint removal.The partial least squares discriminant analysis(PLS-DA)model of 369.164 nm Al(I)element and 428.984 nm Cr(I)element spectral lines is established,It is used to quickly evaluate the effect of laser layered paint removal.The results show that the two partial least squares discriminant models are reliable.Both models include spectral lines based on 428.984 nm Cr(I)elements alone and spectral lines based on369.164 nm Al(I)and 428.984 nm Cr(I)elements,the accuracy of the verification set of the model is 100%.(3)The process parameters of laser layered paint removal are experimentally studied.The influence law of laser power on layered paint removal effect is obtained,the relationship between laser scanning speed and layered paint removal depth and surface morphology is tested,and the best laser layered paint removal parameters are obtained according to the measurement results of surface quality such as surface contact angle and surface roughness after layered paint removal.The results show that the surface quality of layered paint removal is better than that of simultaneous paint removal;When the laser repetition rate is 80 k Hz and the laser scanning times is once,the optimal laser process parameters for removing the finish paint are laser power 24 W and scanning speed 3200 mm/s;The optimum laser process parameters for removing primer are laser power 54 W and scanning speed 2800 mm/s.