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- 01Tribological Behaviors Comparison of Several Stainless Steels under Seawater Lubrication
- 02Comparison of different optimization algorithms used in torque converter design optimization
- 03Research on High Efficient Flank Milling Machining Technology for Similar Ruled 〖JZ〗Surface Integral Impeller Based on Inspection at Original Position
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Fuzzy Sliding Mode Control of Servo Loading Based on Extended State Observer
SANG Yong; JIANG Luming; GUO Lianlong; LIAO Lianjie
Abstract:In order to solve the nonlinear control problem such as clearance and friction existing in the electric servo loading test bench,the sliding mode variable structure control (SMC) was used as the main body to design the loading controller.The whole structure of the servo loading test bench was studied,and a fuzzy sliding mode control (FSMC) strategy based on extended state disturbance observer (ESO) was proposed.On the basis of using ESO to observe the external interference of system,the fuzzy control was designed to adjust the sliding mode surface and sliding mode approach law adaptively,which improved the dynamic real-time following ability and interference compensation ability of the system,and reduced the chattering of the SMC.The simulation results show that the designed fuzzy sliding mode controller based on extended state observer has faster response and robustness than SMC and PID controller.
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Nonlinear Vibration Mechanism of Elastic Beam in Large Overall Rotation with Rotor Eccentricity Effect
ZHAO Lei; ZHAI Ran; YAN Zhaofang; JIAO Likuan
Abstract:In order to realize the high speed and stable operation of flexible machinery such as large overall rotating elastic beams,the Galerkin mode truncation method and Hamilton principle were comprehensively applied to establish the rigid-flexible coupling dynamic model of elastic beam.Differential equations of eccentric motion of rotor were established by rotor dynamics theory.Based on the principle of traveling wave superposition,the high-order Runge-Kutta method was used to decouple the nonlinear dynamics.Finally,the vibration mechanism of elastic beam with rotor eccentricity effect and external excitation was analyzed by time and frequency domain.The results show that under the effect of rotor eccentricity,new low-frequency harmonic components will be derived in the external excitation response;the increase in speed and excitation amplitude will lead to more low-frequency harmonic components in the frequency domain higher than the main vibration,which is easy to cause intermittent vibration of different degrees;the increase in the external excitation frequency will cause the spectral peak in the frequency domain to shift backward;a numerical simulation of the external excitation frequency band from 5 Hz to 35 Hz shows that when the frequency is 25 Hz,the low-frequency harmonic component is twice the value of the main amplitude,up to 0.181 mm.Therefore,time-frequency domain analysis can be used to effectively analyze the mechanism of sudden vibration,and provides important theoretical basis and data support for the dynamic optimization design of large overall rotating flexible machinery.
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Analysis and Evaluation of Core Competitiveness Influencing Factors Based on Cloud Model
XIONG Zonghui; HU Pingping; HE Zhiqi
Abstract:In order to find suitable influencing factors and improve the core competitiveness level of enterprises,an analysis method of core competitiveness influencing factors was proposed based on topologizable conjugate pair analysis and cloud model.Through the analysis of typical agricultural machinery manufacturing enterprises,the topologizable conjugate pair analysis theory was used to establish a virtual-real,soft and hard conjugate pair model from the two perspectives of the internal business process and supply chain of the enterprise,and all the influencing factors set were found.On this basis,a cloud model based on relative preference relationship was constructed,the uncertainty and ambiguity of evaluation information were handled,and the initial importance of the core competitiveness was calculated.The autocorrelation matrix was introduced to correct and judge the importance of each relevant factor,and the key core influencing factors were determined.Finally,the case analysis verifies the scientificity and feasibility of the proposed model,and helps enterprises find the direction of core competitiveness improvement.
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Simulation and Test of Power Shift Hydraulic System for Cotton Picker
PAN Wenlong; NI Xiangdong; YE Haoyun; CHEN Huajun; ZHAO Yongqiang; LIN Yuangang; LI Kezhi
Abstract:In order to ensure the continuity of power output during the power shift process of cotton picker,a regional cross-control strategy was proposed with multiple clutches as the research object.The power shift transmission scheme and shift hydraulic system of cotton picker were designed.The hydraulic transmission system model of cotton picker was analyzed and built.The response of clutch,brake,motor,driving speed and displacement of solenoid valve spool was analyzed.The test results show that the speed curve of the cotton picker rises smoothly,there is no power interruption during the shift process,and there is no obvious power shift impact,which verifies the effectiveness of the strategy.
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Thermal Analysis and Optimization of E-Type Modular Stator Permanent Magnet Synchronous Motor
LIU Zhengwei; SHI Liwei; ZHAO Xin; QIAO Zhiwei; ZHU Yingjie
Abstract:As a new type of motor topology,modular stator permanent magnet synchronous motor is characterized by high fault tolerance and high torque density,but at the same time,there is the problem of large motor losses,which threatens the robustness of motor performance.A E-type modular stator permanent magnet synchronous motor was used as the research object,the motor loss mechanism was analyzed,and the motor loss change law under different operating conditions was studied.The thermal analysis of the motor was carried out by using the bi-directional magnetic-thermal coupling method,and the multi-objective optimization design of the motor was carried out by using the response surface optimization method based on the thermal analysis results.After optimization,the average output torque of the motor is increased by 14.15%,the eddy current loss is reduced by 55.99%,and the average temperature rise of the motor is reduced by 12.62%.Finally,the accuracy of the bi-directional magnetic-thermal coupling method and the effectiveness of the optimized design are verified by experiments.
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Study on Vibration Characteristics of Thermal Barrier Coating Blisk Based on Thermal Fluid Structure
DANG Pengfei; MA Yongzhen; YANG Zhengxin; ZHU Jian; LI Zeting
Abstract:In order to study the influence of complex loads on the vibration characteristics of the integral blade disk,the vibration characteristics of the integral blade disk with thermal barrier coating were studied based on the thermal-fluid-structure coupling method.The integral disk model was simplified,the blade surface was coated with thermal barrier coating and the flow field model of the integral disk was established.The thermal-fluid-structure coupling method was used to simulate the aerodynamic load and temperature load on the surface of the integral disk in Fluent.Finally,the vibration characteristics of the whole blade disk under different working conditions were analyzed by prestressed modal analysis.The results show that the centrifugal load has the greatest effect on the natural frequency of the integral disk,while the temperature has the least effect;in contrast,under different working conditions,the temperature load has no effect on the number of resonance points of the integral disk,while the aerodynamic load increases the number of resonance points of the integral disk.
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Projection Aided Visual Inspection Method for Machine Tool Parts Defects Based on Sparse Matching
LUO Huhui; ZHANG Chunliang; LONG Shangbin; YUE Xia
Abstract:The mechanical arm needs to carry out feature recognition for machine tool parts before automatic and accurate grinding of machine tool parts.The traditional laser lattice scanning has high accuracy,but the equipment cost is high and it is difficult to scale application.Fixed projection was introduced to generate scanning line map,checkerboard map and random gray scale map as measurement aids,and binocular stereo vision measurement was combined to detect part defects,by which the stereo matching of traditional binocular vision for the features that were difficult to recognize for smooth plane parts was improved.The accuracy of the analysis results was verified with the laser lattice scanning results.At the same time,the accuracy of five classical local stereo matching algorithms was compared with the proposed method,and the accuracy correlation analysis of the key parameters of the auxiliary image was carried out.Finally,an adaptive algorithm was introduced to optimize the proposed method to improve the recognition accuracy.The results show that the random gray scale image can significantly improve the matching accuracy,the scanning line optimization and sub-pixel fitting can further improve the matching accuracy,and the accuracy of the scanning image and checkerboard method after optimization is greatly improved.The new method can effectively identify the defect features of plane parts,and the detection accuracy reaches the standard area accounting for more than 98%.
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Evaluation of the Influence of Longitudinal and Torsional Ultrasonic Vibration Assistance on Micro-hole in Electric Discharge Machining Based on Grey Relational Analysis
LI Xiaoyang; YU Daguo; DU Yijie; YIN Zhen; WANG Pengxiang
Abstract:TC4 titanium alloy is a frequently processed material in aerospace field.Due to its difficult cutting characteristics,it is usually processed by electrical discharge machining (EDM),but there are problems in processing efficiency and debris removal.Longitudinal torsional ultrasonic vibration can effectively optimize the above disadvantages,but there is no rigorous quantitative scientific analysis to prove the optimization degree of the longitudinal torsional ultrasonic vibration assistance on EDM.Therefore,a discharge energy model of longitudinal torsional ultrasonic vibration assisted EDM was proposed to explain the discharge mechanism and the influencing factors of discharge energy.Single factor experiment and orthogonal experiment were set up to explore the influence of longitudinal torsional ultrasonic vibration on EDM by significance T test.Grey relational analysis model was established to analyze the influence weight of electrical parameters and the optimal parameter array was selected.Finally,the correctness of the optimal results was verified by hole processing experiment.The results show that the peak current and pulse width have obvious effects on the machining efficiency and quality.The introduction of longitudinal torsional ultrasonic vibration significantly improves the machining performance of EDM.The optimal peak current is increased from 2 A to 3 A,and the pulse width is increased from 125 μs to 150 μs,the material removal rate is increased by 83.8% and the relative tool wear rate,hole taper and surface roughness are decreased by 33.7%,22.3% and 16.4% separately.
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Investigation on Heat Dissipation Performance of Composite Microchannel Structure with Active Liquid Cooling for Power Battery
CHEN Yong; LI Dongming; CHENG Anyu; TANG Kaiwei; HUANG Qiong; ZHU Zhengshen
Abstract:The wide application of large-capacity cylindrical power batteries in electric vehicles has led to an increasingly demand on lightweight and thermal management design for battery pack.In this work,the newly 4680 large cylindrical batteries were taken as research object,four kinds of carbon fiber reinforced composite material (CFRP) cylinder heat dissipation structures with four different micro-channel networks (parallel,bifurcated,serpentine and spiral) were designed,and the influences of microchannel network structure,flow rate of coolant,microchannel diameter and the number of microchannel inlets and outlets on the heat dissipation were analyzed.The results show that the overall performance of the parallel network microchannels is the best among the four kinds of CFRP cylindrical cooling structures; the microchannel diameter offers little influence on the heat dissipation performance of the cylinder structure,but has great effect on the pumping pressure; the heat dissipation performance of the CFRP cylinder with two inlets and two outlets is obviously higher than that of CFRP cylinder with one inlet and one outlet.
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Research on a Flexible Acceleration & Deceleration Algorithm Based on Function Approximation
DING Chengjun; LI Tao; DUAN Ping; SHEN Min
Abstract:Embedded CNC system has many advantages,but its system resources and processing capacity are limited.The trigonometric function acceleration/deceleration algorithm has the advantages of small flexible impact and high accuracy,but its calculation is complex,and it is difficult to meet the high real-time requirements of the system when applied to the embedded numerical control system.To solve this problem,an acceleration/deceleration algorithm was proposed.Based on the best square approximation,the polynomial function was used to approximate the trigonometric function,then the complete acceleration/deceleration equation was deduced and constructed.Then the speed planning of the algorithm under different conditions was analyzed.Finally,the algorithm was simulated and then tested on a CNC platform controlled by MCU.The results show that the algorithm reduces the computational complexity and improves the processing efficiency while preserving the flexibility of the trigonometric function curve.
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Research on the Influence of Piston Preload on Damping Characteristics of High-Speed Train Anti-hunting Damper
DING Mengda
Abstract:In order to implement the independent maintenance requirements of China Railway Group,a study was conducted on the influence of preload on test results during EMU shock absorber maintenance.A certain type of anti-hunting oil pressure shock absorber was taken as the research object,and 3D and flow mechanics models were constructed for the piston damping valve of the shock absorber.Co-simulation software ANSYS and MATLAB/Simulink were utilized to modify preload parameters in order to obtain fluid mechanics changes in the damping valve and damping characteristic curves of the shock absorber.The simulation results were validated using a damper bench,and an analysis was performed on how piston damper valve preload affects damper damping.The test results indicate that when speed does not reach the opening condition of the valve port,changes in damping valve preload do not affect the damping force value of the shock absorber;only when speed reaches this opening condition does preload modification impact damping characteristics;tensile and compressive damping forces increase with an increase in damping valve preload.
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Synchronous Control of Hydraulic Cylinders of Utility Tunnel Spreader Based on IGWO-BP-PID
LIN Zhao; WANG Yanying; ZHANG Yaodong; MA Huabing; WANG Gangfeng
Abstract:Utility tunnel has the adverse condition of large-tonnage bias load hoisting,and it is prone to dangerous accidents.To ensure safety and stability of utility tunnel section hoisting,and to improve synchronous control accuracy of hydraulic cylinder groups of the special spreader,a synchronous control strategy combining IGWO-BP-PID (improved gray wolf optimization-BP neural network-PID) and state difference feedback was studied.Based on the analysis of structure and hydraulic principle of the spreader,the hydraulic cylinders were divided into two groups longitudinally.Gray wolf position was updated in the GWO to achieve optimization of BP-PID parameters by IGWO.Then,three controllers were used to make the system control analyses,and the control effect of IGWO-BP-PID was verified.Finally,synchronous control strategy combining IGWO-BP-PID and state-difference feedback was applied to jointly simulate hydraulic cylinder groups in AMESim/Simulink,and the comparative analysis of the simulation and field test data was carried out.The research results show that IGWO-BP-PID controller has no overshoot and has better control effect.Compared with the conventional PID control,using the proposed method,the oscillation adjustment time of the hydraulic cylinder groups is shortened,and the synchronous control accuracy is higher.The field test verifies the effectiveness of synchronous control strategy of utility tunnel spreader,which meets the engineering construction requirements.
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Analysis and Optimization of Opening and Closing Characteristics of Direct Action Safety Valve
ZHAO Feng; GAO Erfeng; GUO Qi; KONG Decai; LI Mandi
Abstract:In view of the problem that the opening and closing characteristics of a safety valve can not meet the design requirements,liquid flow force analysis is needed.The flow field simulation and analysis was carried out to study the flow characteristics of the fluid inside the safety valve and the action law of liquid flow force .It is concluded that the main reason for the inadequate opening and closing characteristics of the safety valve is the unreasonable outlet structure of the safety valve.Then,based on the results of dynamic analysis and CFD simulation,the AMESim simulation model was built and the experimental curve was repeated.By increasing the outlet position and expanding the outlet diameter,the structure of the safety valve was optimized.The results show that this method can effectively improve the opening and closing characteristics of the safety valve and make its closing pressure meet the requirements of normal closing.
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Research on Five Axis Precision Grinding Technology for Curved Silicon Electrodes
LU Zhen; CHENG Junlan
Abstract:In recent years,new etching technologies emerged,curve structures are designed on silicon electrodes for semiconductor etching.The precision and roughness requirements of curved silicon electrodes are very high，they were produced abroad previously,and the specific process is unknown.An efficient and precise grinding method was developed for curved silicon electrodes.Through the analysis of curved silicon electrode parts,a process scheme of using five axis grinding technology for machining was proposed.Five axis programming software was used for programming,and a five axis grinding center with internal automation technology and digital simulation technology was used to verify the grinding strategy of curved silicon electrodes.The results indicate that this processing technology can improve processing efficiency and product yield,reduce grinding and polishing time,and reduce production costs.
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Design of Permanent Magnet Synchronous Motor Speed Control System Based on Fuzzy Time-varying Sliding Mode
LI Xuyang; LI Xiaoxi; ZHU Qixin; ZHU Yonghong
Abstract:Aiming at the problem of speed fluctuation and instability when the permanent magnet synchronous motor (PMSM) is suddenly loaded,a sliding mode speed regulation method based on integral time-varying sliding mode surface and a new fuzzy gain reaching law was proposed.A time-varying term was added to the traditional integral sliding mode surface by using the integral time-varying sliding mode surface to improve the response speed of the system.The traditional exponential approach law was improved by adding nonlinear functions to weaken the chattering of the system.At the same time,fuzzy algorithm was used to adjust the gain parameters of the approach law according to different system states,focusing on improving the approach speed and anti-disturbance ability of the system.Finally,Lyapunov stability criterion was used to prove the stability of the control system.The proposed control strategy was compared with the traditional sliding mode control strategy in MATLAB/Simulink environment.The simulation results show that the proposed control method has faster response speed,stronger ability to suppress system disturbance and chattering,and better comprehensive performance.
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Laser Cleaning Effect Evaluation System and Systematic Research
CHEN Yinpeng; NING Lichuan; XIAO Xiao; YANG Jintang
Abstract:In order to judge the laser cleaning effect,optimize the laser cleaning process parameters,evaluating the laser cleaning effect is important.Laser cleaning experiment was carried out with 1 000 W laser cleaning machine.Combining experimental data,machine vision technology and surface performance testing technology were used to evaluate the effect of laser cleaning from both macro and micro aspects.Three evaluation indexes of cleanliness,roughness and cleaning efficiency were proposed.According to the evaluation index,the laser cleaning effect evaluation criterion “Lcq” was formulated.Based on this system,an intelligent evaluation system for laser cleaning effect was developed.The test results show that the laser cleaning effect rating evaluation system is objective and accurate,the system operation is stable,and the on-site operation of the laser cleaning equipment can be guided,so as to adjust the parameters of the laser cleaning machine faster and improve the cleaning effect.
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Design of Adaptive Filter for Dynamic Displacement Signal of Heavy-Load Hydraulic Cylinder
DING Zhaoxuan; LIU Kailei; QIANG Hongbin; KANG Shaopeng; ZHU Yong; YIN Penglong
Abstract:In order to better feedback the dynamic displacement information of the heavy-load hydraulic cylinder of the test-bed in the performance test of the large-scale damping damper,so as to truly simulate the vibration excitation signal required by the large-scale damping damper,and then to obtain better characteristic parameters,comparing with the traditional variable step size LMS algorithm,according to the actual vibration loading condition of the heavy-load hydraulic cylinder of the test-bed,under the condition that the expected reference signal was unknown,the original signal was fitted by wavelet transform,and the nonlinear function expression between error and step size was established by MATLAB,and a LMS adaptive filter based on wavelet transform was proposed.Finally,a measurement and control program was written by LabVIEW.The experimental results show that,compared with the traditional variable step size LMS algorithm,the adaptive filter based on wavelet transform has faster convergence speed,smaller steady-state error and stronger tracking ability.In practical application,it has better filtering effect than other types of filters.
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Multi-objective Optimization Design and Simulation of Displacement Sensor for Valve
FENG Shuhui; MIN Wei; WANG Heming; YANG Sen
Abstract:In order to solve the problem of multi-objective multi-criteria electromagnetic structure coupling optimization design of valve displacement sensor,for the long stroke,high precision valve displacement sensor whose radial size is strictly constrained,the optimization algorithm program was written in MATLAB to get the optimal parameter matching group with linearity and sensitivity as the objectives and structural dimensions as the constraints.Based on the results of the multi-objective optimization,the equivalent modeling of the valve LVDT was carried out in the electromagnetic simulation software Maxwell,and the electromagnetic field simulation analysis was carried out on the optimized model and the original model to compare their output characteristics.The results show that for the optimized model,the linearity is 0.19%,and the sensitivity is 23.12 mV/mm.Compared with the original model,the optimized model has a great improvement.This method solves the optimization design of the LVDT structure in a more complete manner,and it can provide references for the optimization and design of the miniaturized valve displacement sensor.
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Study on the Characteristics of Micro-hole Throttling Aerostatic Bearings Based on Different Processing Methods
YU Hechun; KOU Xinjun; HOU Weijie; LIU Haiteng; LI Guangping; ZHANG Guoqing; WANG Wenbo
Abstract:With the development of ultra-precision machining technology and ground micro-low gravity simulation,the performance requirements for aerostatic bearings are getting higher and higher.Because the structural characteristics of the traditional orifice restrictors cannot fully meet the needs of the actual use,the micro-hole throttling aerostatic bearing restrictors with the same order of magnitude as the air membrane gap has attracted attention more and more,due to its good stiffness and bearing characteristics.However,in the development of micro-hole throttle aerostatic bearing,the processing technology of micro-hole limits its popularization and application.Theoretical simulation research on three prevalent micro-hole machining processes was conducted.By constructing simulation models for each process and employing bidirectional fluid-solid coupling simulation methods,the dynamic and static characteristics of micro-hole restrictor aerostatic bearings produced by these processes were compared and analyzed.The results indicate that tapered hole bearings exhibit superior load-carrying capacity compared to the other two types,albeit with higher air consumption and reduced stiffness at low clearances;thin-walled straight-hole bearings demonstrate marginally lower load-carrying capacity,yet they maintain better stiffness at higher clearances;mosaic bearings,while exhibiting less optimal performance in load-carrying,provide greater stiffness and lower air consumption when the clearance is minimal.
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Dynamic Characteristics Simulation Study on Opposed End Curve-Face Gear Piston Pump
ZHOU Kaihong; SHE Dong; ZHANG Yi
Abstract:In order to study the influence of opposed end curve-face gear piston pump parameters on the dynamic characteristics of the pump,the motion equations of the plunger were derived according to the operating principle of the end curve-face gear piston pump.A joint simulation model of the opposed end curve-face gear piston pump was established by using Adams and AMESim software,and the corresponding curves of the outlet flow and pressure of the piston pump at different rotational speeds and eccentricity were obtained by the joint simulation.The results show that as the speed increases,the pump outlet flow and pressure increase,and the pulsation amplitude and pulsation frequency increase;as the eccentricity increases,the pump outlet flow and pressure increase,the pulsation amplitude increases,and the pulsation frequency remains unchanged.
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Synchronous Control of Double Permanent Magnet Synchronous Motor for Gantry Mobile Machine Tool
KUANG Jiawei; ZHOU Xizhi; LI Shi; YAO Zhulin; FANG Wenkang
Abstract:Aiming at the problem of speed synchronization accuracy of gantry dual-drive system,a speed tracking synchronous coupling control method was proposed.In order to realize accurate tracking of external loads,a sliding mode load observer based on Sigmoid function was constructed;a dual-motor mean-value synchronous difference controller combined with an integral sliding mode was designed,and a tracking error backstepping controller was combined to formulate a coupled control strategy of speed synchronization error and tracking error,and simulation tests were completed for two load cases.The simulation results show that compared with the PID control,the coupled control strategy reduces the synchronization error by 52.4% and the response time by 75%;compared with the single backstepping control,the coupled control strategy reduces the synchronization error by 39.1% and the response time by 17%.
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Analysis of Pressure Pulsation and Hydraulic Performance of Centrifugal Pump Based on Curvature Control Leading Edge
LI Wei; ZHOU Xiancheng; MOU Lei; WU Wei; ZHAO Xingan
Abstract:Volute centrifugal pump is the core equipment for fluid transportation.The pressure pulsation and hydraulic performance have a significant impact on the stability,noise and life of the pump.Combined with the design method of curvature control leading edge,as the growth rate of 1.19%,0.47% and 0.32%,volute centrifugal pumps with the leading edge axis ratio of 0.96,2.11,3.11 and 4.11 were established.Taking the steady calculation results of SST κ-ω model as the initial condition,the unsteady analysis of κ-ε RNG model was carried out.The pressure pulsation was analyzed by frequency domain diagram,and the hydraulic performance was analyzed by vector cloud image.The results show that the optimal flow rate of the designed model is 35 m3/h,and the error between design efficiency and simulation efficiency is only 2%; the axial length ratio of the leading edge is different,and the pressure diffusion in the flow channel is different;when the axis ratio of the leading edge is 3.11,the outlet pressure pulsation is low,and the pressure pulsation is more likely to occur in the low frequency region;when the axis ratio of the leading edge is 0.96,the pressure fluctuation range is small,which is suitable for the working condition with large head change in a certain flow range.
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Research on Modeling and Simulation of New Variable Displacement Oil Pump Based on AMESim
ZHANG Wei; ZHAI Yifei
Abstract:Taking a new vane plunger composite type of two-stage variable vane pump as research subject,its key characteristic is to reduce high-speed vane impact by embedding the top of the vane into the stator and rotating the rotor,vane and stator simultaneously.The instantaneous flow characteristics equation of the pump under the compound action of vane plunger was derived.A proportional solenoid valve model,an instantaneous flow model,a variable mechanism model,were built.The characteristics of the two-stage variable vane pump were simulated based on AMESim simulation platform.The relevant verification was carried out by bench test.The experimental results show that the pressure-flow curve of the pump matches well at medium and low speeds,indicating accurate modeling of flow and variable displacement;the acceleration and deceleration curves indicate that the pressure regulation of the pump is stable under different duty cycles of the proportional valve.
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Research on Control Strategy of Boom Potential Energy Regeneration Based on Multi-simulation Model
YUAN Yulin; HE Xiangyu; JIANG Mengjun; LIU Qi; ZHANG Jiayan
Abstract:A large amount of gravitational potential energy will be wasted when the boom drops frequently in hydraulic excavator working process.Therefore,boom potential energy regeneration can effectively improve the energy efficiency of the excavator.Based on the experimental platform of 1.7×104 N hydraulic excavator,a combined energy-saving boom structure and its hydraulic regeneration circuit were designed,the boom dynamics model,hydraulic model and controller model were established to carry out multi-simulation model co-simulation,and a control strategy was proposed for the boom potential energy regeneration based on fuzzy PID control strategy.The results show that the energy saving efficiency of the boom potential energy regeneration system controlled by fuzzy PID is 25.57%,which is higher than the 18.04% of the traditional PID control strategy,compared with the traditional PID controlled no-accumulator model.
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Research on the Pressure Loss of the Multi-way Valve Port of the Positive Flow Hydraulic Excavator
MA Junhui; GAO Chunying; CHEN Junxiang; LIU Yinghao; AI Chao
Abstract:The hydraulic system of excavator has problems such as pipeline loss,overflow loss,throttling loss and leakage loss,which lead to large power loss and low energy utilization rate in the process of excavator operation.To improve the power utilization of excavator hydraulic system,taking the positive flow excavator as the research object,the electromechanical hydraulic joint simulation platform was established.Aiming at the problem of large pressure loss of multi-way valve,the method of changing the flow area of the main valve special-shaped valve port area was proposed,which reduced the local pressure loss and improved the power utilization rate of the hydraulic system.Taking the bucket linkage as an example,changing the flow area of the inlet and outlet of the bucket main valve and the bucket confluence valve and the matching between them,the driving efficiency of the bucket action is increased by 4%,and the power loss of the hydraulic system is reduced.
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Simulation and Analysis of Operation Characteristics of Ship Lubricating Oil System
OUYANG Wenheng; YIN Yuxian; LIU Xiaofeng; HU Zhihua
Abstract:The main function of the ships lubricating oil system is to provide lubricating oil that meets the quality and quantity requirements for the power unit to ensure the normal lubrication,cooling,anti-corrosion,cleaning,and power transmission of moving parts.Under different operating conditions,the internal parameters of the lubricating oil system will change significantly，which will affect the normal operation of the ship system.MATLAB Simulink was used to simulate the lubricating oil system based on the actual use demand and operation of the project to maximize its benefits.The simulation was mainly introduced from several aspects,such as startup stage,stability stage,shutdown stage,fault stage,etc,to restore the actual operation of the oil system to the greatest extent.The results show that the simulation technology can effectively simulate the operation of marine lubrication system under various working conditions,help to optimize the system design and operation strategy,maximize the benefits of lubrication system,and ensure the normal operation of marine system.
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Analysis and Optimization of Influence of the Preload Torque of Servo Valve End Cover on the Mechanical Zero Position
GUO Jiali; SHEN Yiming; JIANG Jinlin; LI Chao; CHEN Peiyuan; LI Yichen; HE Mengzhang
Abstract:The structure of a certain type of servo valve end cover was introduced.The structure stress condition at the position was analyzed.The effect of preloading torque on the stress and strain of the end cover structure was simulated using finite element software.Through analysis,it is concluded that a large preload torque not only causes the damage risk to the end cover material,but also causes the change of the mechanical zero position of the servo valve,thus adversely affecting the stability of the servo valve performance.By analyzing improvement measures,appropriate preload torque and anti-loosening measures were selected.The practical results verify the effectiveness of the improvement measures.
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Research Status and Development of Mechanical Equipment Fault Detection Based on Acoustic Signal
LI Yanan; WANG Chunguang; ZONG Zheying; WANG Shuai; WANG Zhen; DU Yingjie
Abstract:Since modern times,Chinas industry has developed rapidly,showing a trend of scale,complexity,and integration.The long-term,stable,and efficient operation of mechanical equipment is the key to the rapid development of industry.Mechanical equipment is prone to sudden shutdowns due to long-term operation,reducing the economic benefits of the factory,and even posing a threat to human life safety.Therefore,mechanical equipment fault detection is of great significance for the development of Chinas industry and the improvement of economic benefits.At present,the common fault detection methods are mainly manual detection and vibration monitoring.Manual detection and inspection cycles are long,faults cannot be detected in a timely manner,and subjectivity is strong.Vibration detection requires high installation requirements for detection equipment.Because the sound of mechanical equipment changes when it is damaged,and the collection method of sound signals is non-contact,which is convenient for installation,sound signals are gradually applied to the field of fault detection of mechanical equipment.Fault detection technology based on sound signals can detect mechanical equipment faults in a timely manner,repair them in a timely manner,and reduce economic losses.The research progress of mechanical equipment in the field of fault detection both domestically and internationally were reviewed from the perspectives of machine learning and deep learning,and proposed the future research focus and reference direction of mechanical equipment fault detection technology based on acoustic signals,aiming to provide reference for fault diagnosis of mechanical equipment.
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Research on Fault Diagnosis for Aero-Pipeline Clamp Based on Space-Time Model
WANG Tongyu; YUAN Shengyou; LI Kaitai; MI Chengquan; LIN Jieru; YANG Tongguang
Abstract:Aiming at the problem that the vibration signal of aviation hydraulic pipe clamp is interfered by strong noise,it is difficult to accurately identify aviation clamp fault,a new method of aviation clamp fault diagnosis based on space time model was proposed.A spatial feature extraction model was established to carry out local fusion of fault features of aviation clamp.The GRU module was introduced into the spatial model to extract the global features of the aviation clamp fault signal.The results show that:the designed space-time fault diagnosis model can be used to realize accurate identification of aviation clamp faults.It was compared with five advanced fault diagnosis methods currently used,including deep convolutional neural network model,gated recurrent unit neural network model,recurrent neural network model,support vector machine and error back propagation neural network model.The proposed method has advantages in fault identification of aviation clamp.
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Fault Feature Extraction of Valve Spring of Emulsion Pump Based on Vibration Intensity
MA Baoyu; LIAN Zisheng; MAO Hucheng
Abstract:Aiming at a series of problems such as difficulty in fault identification and fault feature extraction of distribution valve spring of emulsion pump,a method for fault feature extraction of distribution valve spring of emulsion pump was proposed based on vibration intensity.The simulation model of the emulsion pump was built based on AMESim software.By setting different parameters respectively to simulate the failure forms of suction and discharge valve spring,the outlet pressure signals under normal and suction and discharge valve spring failure state were obtained.According to the vibration intensity theory,the outlet pressure signals were converted into acceleration signals,and the intensity characteristic factors of the outlet pressure signals were extracted and compared in the frequency domain.The results show that the influence rules on the outlet pressure intensity characteristic value are different when the suction and discharge valves fail respectively.With the deepening of the fault degree of the suction valve spring,the characteristic value of the outlet pressure intensity increases from the normal 15.82 mm/s2 to 20.58 mm/s2,28.18 mm/s2,34.85 mm/s2,and it reaches its maximum value at fracture; with the deepening of the fault degree of the discharge valve spring,the characteristic value of outlet pressure intensity decreases from the normal 15.82 mm/s2 to 15.77 mm/s2,14.88 mm/s2,9.28 mm/s2,and it reaches its minimum value at fracture.The results provide a theoretical basis for the subsequent fault diagnosis of emulsion pump.
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Remaining Life Prediction of Turbofan Engine Based on Feature Selection and Transformer
LIU Gengxin; DONG Xinmin; ZHANG Ruibo; CHEN Yang
Abstract:Aiming at the problem that the traditional residual service life prediction model is difficult to solve the problem of long-term dependence and that different feature combinations have a great impact on the prediction accuracy of the model,a residual service life prediction model based on feature selection and Transformer was proposed.The maximum correlation and minimum redundancy feature selection algorithm based on mutual information was used to capture the relationship between features and labels,features and features,and the best feature combination was obtained.Then taking Transformers encoder as the main body and adding the gated convolution unit,a prediction model was formed,so that the model could fully capture the global information and improve the operational efficiency,and pay more attention to local information.The model parameters were determined by particle swarm optimization.Finally,the variable data of the optimal feature combination were input into the model to realize the prediction of the remaining service life of the turbofan engine.This method was verified in C-MAPSS data set,and comparative experiments were carried out.The results show that the prediction error and model efficiency are improved to some extent.
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Prediction of Industrial Equipment Health Status Based on ICEEMDAN Fuzzy Entropy and Bi-LSTM
LU Guangzhi; LI Jingzhao; ZHANG Jinwei
Abstract:The health status of industrial equipment is related to the normal operation of industrial production.Therefore,a method based on improved complete ensemble empirical mode decomposition with adaptive noise (ICEEMDAN) and bidirectional long-term short-term memory network (Bi-LSTM) method was proposed for predicting the health status of industrial equipment.ICEEMDAN was used to decompose the original audio signal to obtain several intrinsic mode function (IMF) components,the best component group was selected by calculating the correlation coefficient for signal reconstruction,and then the fuzzy entropy structure of the reconstructed IMF component was calculated to reconstruct the feature vector set.The set of feature vectors was finally input to the Bi-LSTM network for model training and prediction.The experimental results show that,compared with other models,the health status prediction method of industrial equipment based on ICEEMDAN fuzzy entropy and Bi-LSTM can effectively extract the audio signal features and accurately predict the health status.
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Fault Diagnosis of Abnormal Vibration of Variable Speed Running Gear Based on Multi-sensor Data Fusion
ZHOU Guangxiang; LI Peng; JIANG Deye
Abstract:The poor diagnosis performance of abnormal vibration fault of variable speed running gear will increase the vehicle maintenance cost and shorten the service life of the gear.In order to identify the gear fault in time and ensure that the vehicle transmission assembly has good vibration characteristics,a method for diagnosing abnormal vibration fault of variable speed running gear based on multi-sensor data fusion was proposed.The multi-sensor data fusion technology was analyzed,the theoretical framework of abnormal vibration fault diagnosis of variable speed running gear was grasped.On this basis,referring to the sensor fusion module,feature level parallel multi neural network local diagnosis module and terminal classification module,and combining the variational mode decomposition,multi-channel weighted fusion and single hidden layer feedforward neural network training algorithm,the fault diagnosis of abnormal vibration of variable speed running gear was realized from signal acquisition,signal feature extraction and signal feature classification.The experimental results show that when the gear is slightly worn,the amplitude of wear vibration signal is from 20 mV to 40 mV,and the frequency of wear vibration signal is from 0 to 4 000 Hz; in case of moderate wear,the signal amplitude is from 30 mV to 55 mV and the signal frequency is from 3 000 Hz to 7 000 Hz; in case of severe wear,the signal amplitude is from 50 mV to 70 mV,the signal frequency is from 6 000 Hz to 12 000 Hz,and the diagnosis results at each stage are consistent with the actual turning point of the fault degree.It can be seen that in the case of the same number of samples,the predicted value and the true value of the proposed fault diagnosis method are the same,and the diagnosis performance to fault degree and fault type is good.
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Fault Monitoring of Process Industry System Based on DSC-DenseNet
WANG Kai; YASENJIANG·Jiarula
Abstract:Tennessee Eastman process (TEP) data have the characteristics of high latitude and high coupling,so it is difficult to extract the data characteristics.In order to further improve the recognition rate of fault monitoring in the process industry system,1D-DenseNet was combined with deep separable convolution (DSC),the efficient feature extraction ability of DenseNet was used,and DSC was used to reduce the calculation parameters,so as to improve the diagnosis efficiency.To provide fault monitoring mode based on DSC-DenseNet,the data were normalized and random seeds were added to avoid over-fitting.Then the processed results were used as the input of DSC-DenseNet for feature extraction,and the output results were transmitted to the full connection layer for fault classification.Finally,the accuracy test was carried out on the TEP dataset.The results show that the method based on DSC-DenseNet can be used to effectively distinguish the fault types,and the accuracy of fault classification reaches 98.8%.It is proved that DSC-DenseNet has better fault identification effect than traditional DenseNet.
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Research on Component Life Modeling of Aero-engine Fuel System
YUAN Zhongda; CHENG Xiuquan; WANG Dawei
Abstract:In order to solve the problem that reliability of fuel system components is difficult to estimate,the working time data of fuel pump components,hydraulic mechanical components,fuel flow sensors and fuel nozzles were collected.Weibull probability charts were drawn respectively for the working time of different components.Three-parameter correlation coefficient optimization method was used to estimate the parameters of Weibull distribution model.The reliability functions,failure efficiency functions and failure probability density functions of different components were obtained according to the parameter estimates.Finally,reliability evaluation and analysis of fuel system components were carried out.The results show that:as a complex mechatronic system,Weibull distribution model can be used to effectively evaluate the aero-engine fuel system components service life,and can be used to analyze the reliability of aero-engine fuel system components.
