Research On Online Monitoring System Of Laser Shock Peening Based On Acoustic Signal Analysis

Laser shock peening is a new material surface treatment technology.When materials have been strengthening by laser shock peening,it can significant prolong the fatigue life and improve the corrosion resistance and wear resistance of the material.Since the effect of laser shock peening is affected by many factors,such as laser pulse width,wavelength,pulse energy,pulse frequency,constraining layer material and absorbing layer material,it is critical to establish the effective monitoring of the strengthening process for the optimization of laser shock peening and the process quality evaluation.To this end,this paper designs a online monitoring system of laser shock penning by taking advantage of the laser plasma phenomenon generated during the laser shock peening process,and realizes the on-line monitoring of the laser shock process by studying and analyzing the plasma acoustic wave phenomenon.The process determination of laser shock peening is given.In addition,the system combines the residual stress value of the machined workpiece to establish the relationship between the residual stress value and the plasma acoustic wave signal.The specific work as follows:1.The overall planning of the online monitoring system was made.The phenomenon of plasma acoustic wave and its propagation process during the laser shock peening process were analyzed and contrasted with the ordinary acoustic signal.The plasma acoustic wave signal is collected by using the acoustic emission technology of non-destructive testing,and the online monitoring system hardware platform was designed for the laboratory laser shock peening equipment.2.The processing method of plasma acoustic wave signal was studied,and various methods were analyzed for the acoustic signal which was collected during the laser shock peening process.First,the acquired signal data are preprocessed,including signal downsampling and denoising,to increase efficiency of signal processing and obtain signal data with high quality information.Subsequently,the pre-processed acoustic signals are analyzed by using parametric analysis and waveform analysis.The parametric analysis method analyzed the relationship between the signal characteristic parameters and the residual stress of the specimen,while the waveform analysis method is used to analyze the acoustic signals of different processing technologies from the time and frequency domains of signals.It shows that the plasma acoustic wave signal contains process information of laser shock peening and the change relation of processing performance,which can monitor the laser shock strengthening process.3.Based on the research results,the online monitoring system of laser shock peening was developed by using MFC software technology.The system framework,design scheme and the specific implementation process were introduced.Finally,the online monitoring test of laser shock peening was carried out by the software to verify the software system function.