Research On Acoustic Emission Source Location System For Structural Damage

Structural safety monitoring is related to the safety of people's lives and property.However,accidents caused by structural safety problems continue to emerge every year.Therefore,it is of great significance to find a safe and reliable non-destructive testing method.Compared with other non-destructive testing methods,acoustic emission testing technology has the advantages of non-radiation,non-pollution,real-time and applicability,so it has been widely promoted.The purpose of this paper is to monitor the safety of structure by combining acoustic emission detection technology and embedded technology,and to locate the damage point of structure,that is,the location of acoustic emission source,so as to effectively identify the fault point for maintenance personnel.Firstly,this paper introduces the development of acoustic emission source location technology,and puts forward the research emphasis of this paper,including the design of the software and hardware platform of acoustic emission system,the plane location of acoustic emission source,the design of acoustic emission wireless measurement network and the division of warning level in monitoring area.The hardware and software platform of AE adopts the architecture of FPGA + MCU.With the characteristics of high speed,parallelism and flexibility,FPGA is suitable for controlling AD chip as the main control chip to complete the functions of acquisition,processing,storage of acoustic emission signal and time synchronization of acoustic emission measurement network.At the same time,according to the design requirements,the measurement nodes are divided into ordinary nodes and terminal nodes.The MCU of terminal node chooses BCM2837 chip,which has powerful performance and supports many operating systems.Some function of common node is deleted compared with terminal node,and MSP430 is chosen for MCU considering cost.In addition,this paper uses QT + SQLite to provide a friendly operation interface for hardware and software systems,as well as convenient data management methods.This paper elaborates the working principle and design structure of each part of the acoustic emission source positioning platform,which provides the hardware and software basis for achieving the goal of this topic.Aiming at the shortcomings of current AE source location methods,this paper proposes four groups of location methods.By using AE start point detection method based on hardware synchronization mechanism,the time delay of AE signal arriving at different sensors is measured.This method can greatly improve the real-time performance of the system,reduce network load and simplify the algorithm.At the same time,this paper combines the least squares method with Taylor iteration method,and takes the coordinates of acoustic emission source obtained by the least squares method as the initial value of Taylor iteration algorithm,which reduces the number of iterations and improves the speed of the algorithm.In this paper,a wireless acoustic emission measurement network is set up,and the time synchronization of the acoustic emission wireless measurement nodes is carried out.At the same time,the organization of the measurement nodes is designed to monitor the development track of the acoustic emission source.At the same time,the paper divides the signal waveforms according to the similarity of waveforms,filters out the noise and the bands that do not meet the requirements of positioning.It provides a technical idea to improve the stability of positioning system and avoid mispositioning.Finally,the SOFM-EEG visual warning model is established,and the security level of the monitoring area is classified by the self-organizing feature mapping network(SOFM),and the warning level is matched and visualized according to the EEG visual experiment results.