Key Technology On Dynamic Stress Monitoring And Strain Field Visualization Of Maglev Vehicle Levitation Chassis Bracket Arm Structure

The bracket arm of the levitation chassis is a key load-bearing component in maglev vehicles,providing support,guidance,and shock absorption during operation.The structural reliability of the bracket arm is essential for the safe and stable operation of maglev vehicles.However,as high-speed maglev technology continues to develop rapidly,relevant structural design lacks data support and has not yet formed industry standards or theoretical systems.Therefore,it is necessary to monitor and analyze the structural status in real-time during the vehicle’s service stage to ensure operational safety and provide data support for structural optimization and improvement.This study focuses on the bracket arm of the levitation chassis of a 600 km/h high-speed maglev vehicle and uses fiber Bragg grating dynamic stress monitoring technology and load-strain linear superposition principle to design and implement a dynamic stress monitoring and strain field visualization system.The goal is to achieve realtime dynamic stress monitoring and three-dimensional visualization of the strain field under operating conditions.The main research contents of this study are as follows:(1)Structural load analysis and finite element simulation of the maglev vehicle levitation chassis bracket arm were carried out.Firstly,based on the operating principles of maglev vehicles,this study introduced the functions of the levitation chassis structure and the relationship between the bracket arm and the levitation chassis,discussing the key role of the bracket arm structure in maglev transportation systems.Secondly,a load analysis of the bracket arm structure was carried out,detailing the sources and characteristics of lateral loads,vertical loads,and longitudinal loads.Finally,for two main load-bearing states of the bracket arm structure under typical working conditions,finite element simulation methods were used to construct numerical models of structural strain/displacement response under typical loads,laying a foundation for overall design of bracket arm structure status monitoring and visualization system.(2)Construction of an on-board dynamic stress monitoring system was carried out.In order to obtain real-time strain data for field reconstruction,a dynamic stress monitoring system suitable for high-speed maglev vehicle service environments was designed and implemented.Firstly,according to the distribution law of stress fields,a sensor network layout was designed using fiber Bragg grating sensors to build a sensor network.Secondly,a multi-channel on-board strain data acquisition system was built using an integrated high-speed demodulation terminal for wavelength acquisition and transmitted to an on-board computer through UDP protocol.Finally,upper computer software for dynamic stress acquisition was developed to perform realtime acquisition and analysis processing of sensor data.At the same time,design patterns and database performance were optimized to achieve high-speed data storage and low-bandwidth transmission,providing data support for visualization system of bracket arms.(3)Field reconstruction and visualization system research were carried out.Firstly,according to modal superposition theory of multi-degree-of-freedom systems,a field reconstruction method based on load-strain linear superposition principle was studied.Load weights were calculated using measured strain values and load-strain response matrices.Strain field and displacement field data were obtained by combining structural strain/displacement matrices under separate action of each load.Secondly,a technical solution for visualizing threedimensional objects based on mesh drawing was designed.Real-time coloring of threedimensional structures was achieved through texture mapping,with color gradient textures generated through scale interpolation.Finally,combined with field reconstruction principles and visualization technology,three-dimensional visualization software for bracket arm structure was designed and developed that could receive real-time monitoring data from onboard monitoring system for field reconstruction calculation in real time to achieve dynamic stress monitoring and strain field visualization of maglev vehicle levitation chassis bracket arm structure.(4)Performance verification of dynamic stress monitoring and strain field visualization system.On one hand,an experimental platform was built using a reduced-scale model of a bracket arm and fiber Bragg grating dynamic stress monitoring system.A load loading experimental scheme simulating actual service conditions was formulated according to experimental results to evaluate three-dimensional visualization effect and reconstruction error of system.On other hand,application verification was carried out on an actual maglev train.Experimental results under two typical service conditions:vehicle stationary and uniform motion were analyzed.Visualization models under two working conditions were compared with simulation models.Results show that dynamic stress monitoring and strain field visualization system has good stability and accuracy.This study provides a new method and technology for status monitoring and visualized maintenance of maglev vehicle levitation chassis bracket arms structure which was important for supporting development of new generation high-speed maglev trains..