Research On Acoustic Emission Signal Acquisition System Based On PCI

With the wide application of helicopters in various fields,how to ensure the safe operation of helicopters becomes more and more important.As an important part of the helicopter rotor,the hub has a complicated structure and is subject to high-intensity alternating loads for a long time,which is prone to failure.Real-time condition monitoring of the hub and fault prediction are of great significance for ensuring the stable and reliable operation of the helicopter.In recent years,the monitoring of crack initiation and propagation of helicopter moving parts by acoustic emission detection technology has become one of the hot topics in research,and signal acquisition is the basis of acoustic emission detection technology.In this paper,based on the need of Crack Acoustic Emission Detection for helicopter hub central parts,an acoustic emission signal acquisition system based on PCI interface is designed.Through the analysis of the requirements of the acquisition system,the corresponding hardware scheme and software scheme are designed,and the design process and implementation method of the scheme are elaborated.The hardware of the acoustic emission acquisition system consists of five parts: sensor and preamplifier,acoustic emission signal conditioning circuit,analog-to-digital conversion circuit,PCI interface circuit and FPGA control circuit and control logic.SR150 M and PAS of the Soundwel Company are adopted as the sensor and preamplifier,ADA4898-2 is used to construct the filter circuit of variable passband,ADG1439 is used to select nine kinds of filter passband,ADS8422 is used to realize 16 bits high precision sampling at 4 MSPS sampling rate,FPGA is used to complete the selection of filter passband and data acquisition control,and PCI9054 is used to transmit the sampled data to PC through DMA.The software system is composed of PCI driver,interface function library and corresponding program for acquisition and management.The control of A/D sampling rate,filter passband selection and DMA transmission is accomplished by PCI bus.The software system can save the AE data by collected,drawing the waveform,extracting and displaying the AE features.It has the basic functions of detecting and analyzing AE signals.Finally,the whole data acquisition system is debugged and calibrated by the analog acoustic emission signal source,and the acquisition and processing of the lead-breaking acoustic emission signal on a certain titanium alloy material is completed,and the main functions and performance of the system are verified.The final experimental verification shows that the system achieves the data acquisition of two AE signals with the highest sampling rate of 4 MSPS and the sampling resolution of 16 bits.At the same time,it can quickly extract the AE features such as ringing count,amplitude,energy,arrival time and duration,and store the sampled waveform data and characteristic parameters in real time.This paper lays a foundation for the research of crack acoustic emission detection of helicopter hub central parts.