| Carbon Fiber Reinforced Plastics(CFRP)is an advanced composite material with high axial strength and corrosion resistance that is widely used in aerospace,automotive manufacturing and sporting goods.Laser processing of CFRP can overcome the problems of cracks,delamination and tool wear caused by traditional mechanical contact processing means,but it is easy to produce heat-affected zone,affecting the processing process,it is necessary to introduce monitoring means in the processing process to monitor the impact of laser on CFRP in real time.Compared with infrared monitoring and image monitoring,laser processing monitoring through acoustic signal has the advantages of simple system and convenient operation,but the relevant research is not enough at present.In this paper,the acoustic signal generated by laser stripping of CFRP is tested.The main work and conclusions are as follows:(1)Study on the relationship between laser processing CFRP acoustic signal and stripping process.A 1064nm laser was used to perform stripping experiments on a CFRP plate to investigate the relationship between acoustic signal and laser stripping cross-sectional area and depth under different laser filling spacing,scanning speed and scanning Angle.The results show that the relationship between laser parameters and acoustic signal is that the scanning speed decreases and the energy of acoustic signal increases.The relationship between acoustic signal and laser stripping CFRP is that the average energy of acoustic signal is proportional to the cross-sectional area of laser stripping.(2)Study on acoustic signal characteristics of CFRP processed by laser.Based on the study of the relationship between laser processing CFRP acoustic signals and the stripping process,the relevant experiments were redesigned to pay attention to the phenomenon causes and influencing factors of the regularity of the acoustic signal ups and downs.The results show that:Laser filling spacing is an important factor causing the ups and downs of acoustic signal,laser filling spacing is low,after a laser to the previous laser influence area,laser efficiency is reduced,the intensity of the acoustic signal will be reduced,the volume of CFRP removed and the influence area is reduced,and then a laser will not be affected by the laser,The intensity of the acoustic signal returns to its normal amplitude,resulting in overall ups and downs of the acoustic signal.In addition,the attenuation part of the acoustic signal after the peak is studied.Using different laser parameters to compare the attenuated part of the signal,it is found that the laser scanning speed is reduced,and the oscillation amplitude is larger and the duration is longer.By replacing different experimental materials and comparing with CFRP,it was found that the attenuation part was almost not affected by the change of experimental materials.In the process of repeated laser peeling of paint layer,it was found that under different cleaning effects,the frequency spectrum of the attenuation part was weakened and the high-frequency part was enhanced with the increase of laser action times.(3)Explore the mechanism of acoustic signal,and carry out experiments on shock wave generated by laser processing CFRP.The Schlieren method was used to photograph the dust gas accompanying the shock wave,and the diffusion trend and process of the dust gas were obtained.It was found that the scanning Angle hardly affected the process.In addition,another beam of light is passed over the laser processing area to study its deflection.The results show that the shock wave propagation velocity is about 12000mm/s at the laser machining center,and decreases to about 2000mm/s with the increase of distance. |
PDF Full Text Request