Research On Key Technology Of Strain Detaction Of Hydraulic Based On Fiber Grating

With the development of social economy,the air transport industry plays an increasingly important role in national life.The engine is known as the "heart" of the aircraft,while the hydraulic piping system is called the "blood vessel" of the aircraft engine.Because the hydraulic pipeline system works in a harsh working environment,it will cause the pipeline to be damaged or even broken from time to time,which brings great safety hazards to the flight of the aircraft.In order to avoid the tragedy of machine destruction and death,how to detect the stress and strain status of hydraulic pipelines online has become an important content that scientific and technological personnel must pay attention to.Traditional strain measurement methods such as resistance strain gauge type are complex and susceptible to electromagnetic interference,which cannot meet the requirements of distributed detection of complex pipeline systems.Due to its strain sensing characteristics and the ability to reuse multiple sensors in series,fiber gratings are currently widely used in the aerospace field for strain detection of aircraft fuselage,wings and internal structures.In this paper,it is proposed to use fiber gratings to perform strain detection on the surface of hydraulic pipelines.Firstly,the packaging method of the FBG sensor is analyzed based on the strain principle of the FBG.Secondly,the response characteristics of hydraulic pipelines under different working conditions are studied to provide reference for the pasting position.Finally,the signal processing method of fiber grating is studied,and the number of fiber grating uses is further expanded.The main research contents of this thesis:This paper analyzes the research status of fiber grating strain sensing at home and abroad,and proposes to use fiber grating to carry out distributed detection of hydraulic pipeline strain in view of the problems existing in hydraulic pipeline strain detection.Combined with the principle of strain detection of hydraulic pipelines and the strain sensing principle of fiber grating,a three-layer strain transfer model is proposed,the theoretical formula of strain transfer of fiber grating is derived,and the factors affecting the strain transmission rate are analyzed,and the influence of different factors on the strain transfer efficiency is obtained.ANSYS software was used to establish the strain model of the fiber grating sensor to measure the hydraulic pipeline,and the strain transfer theory was verified through simulation analysis,which provided a theoretical reference for the packaging of the fiber grating sensor.Models of hydraulic straight pipes and hydraulic Z-pipes widely used in hydraulic piping systems were established,and ANSYS software was used to analyze the vibration response of hydraulic lines under fluid-structure interaction and basic excitation.Aiming at the doping noise of FBG signals in the process of FBG multiplexing,CEEMDAN combined with the wavelet filtering algorithm with improved threshold is proposed for FBG signal processing.The filtered signal is compared with the traditional wavelet filtering and EMD filtering results,and the signal-to-noise ratio and mean square deviation of the signal are used to evaluate the filtering effect.