Acoustic emission monitoring and heat-affected zone evaluation of CFRP laser cutting

Abstract

Acoustic emission (AE) technology can be used to analyze the mechanism and evaluate the size of the heat-affected zone (HAZ) during laser cutting carbon fiber-reinforced plastics (CFRP). A hardware acquisition platform and data collection system for collecting AE signals were first built. Experiments of 17 groups with different laser repetition rates and 13 groups with different galvanometer scanning speeds were carried out in CFRP laser processing. Through the spectrum analysis of fast Fourier transform, it can be observed that the frequency distribution of the AE signal was located only at the integer multiple of the laser repetition rate, and the maximum frequency of the AE signal was the product of the laser repetition rate and the number of AE oscillation cycles between two adjacent laser pulses; The critical state of laser ablation and denudation (plasma impact) was described by root-mean-square (RMS) characteristics of the AE signal. When the laser repetition rate is 50 kHz and the scanning speed is 2500 mm/s, laser ablation and denudation are both very intense, which is helpful to improve the processing efficiency; As the laser repetition rate increases, the RMS value of AE increases first and then decreases with the synchronization of the HAZ. By monitoring the RMS value, the value of HAZ can be obtained clearly.