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    Volume 50,2022 Issue 24
    • Experimental Study of Axial Ultrasonic Vibration Turning 316L Stainless Steel
      ZHU Jian; YIN Zhen; ZHANG Kun; ZHANG Peng

      Abstract:A single-factor comparison experiment of axial ultrasonic vibration turning and conventional turning of 316L stainless steel was carried out, and the influences of the ultrasonic amplitude and processing parameters (cutting speed, feed) on cutting force and surface roughness were studied. The experimental results show that using axial ultrasonic vibration turning can effectively reduce the cutting force, surface roughness and surface profile height; compared with conventional turning, the smaller the ultrasonic amplitude is, the more obvious the improvement effect of surface roughness is; when the feed rate is increased from 5 μm/r to 25 μm/r, the main cutting force and surface roughness of the axial ultrasonic vibration turning are reduced by 17%~21% and 21%~28% respectively compared with conventional turning; with the increase of cutting speed, the surface roughness and cutting force of the axial ultrasonic vibration turning firstly decrease and then increase, and there is an optimal cutting speed range, and the surface roughness can be reduced by 29.9%, and the cutting force can be reduced by 30.1%.

    • Analysis of Positioning Error and Compensation Method of Bearing Ring Based on Deformation of Load Cell
      DUAN Chenglong; ZHANG Mingzhu; DU Honglin; QIU Ming; ;LI Zhiwei

      Abstract:A compensation method for the positioning error caused by the deformation of the load cell was proposed. For the electromagnetic centerless clamp grinding bearing ring, the load cells were installed on the front and rear supports respectively. When supporting the radial positioning bearing ring, the load cell accurately measures the supporting force of the bearing ring and shifts accordingly. By analyzing the positional relationship between the centerless grinding support and the workpiece and the change law of the positioning error during the grinding process, the calculation formula of the positioning error caused by the offset of the support caused by the force deformation of the load cell was deduced, and it was proposed to control the grinding wheel carriage feeding to compensate the positioning error. The results show that the deformation of the load cell will affect the machining accuracy of the ring;this method can be used to compensate the positioning error. The comparison of the grinding time before and after compensation shows that the method can improve the cylindrical grinding efficiency of the bearing ring.

    • Research on Modular Reconfiguration Design for Remanufacturing Upgrade
      KANG Bokai; ZHANG Xiufen

      Abstract:Aiming at the problem that the product technology is backward and can’t be reused in remanufacturing, a modular reconfiguration design method for remanufacturing upgrade was proposed. In order to facilitate the disassembly, assembly and recycling of products, green modules of products was divided based on the design structure matrix, and the prototype system of remanufacturing module division platform was developed based on MATLAB, parts with the same recycling type was grouped into clusters to form new modules. For the modules with conflicts, the rationality analysis method of module division results was proposed due to the rationality criteria of function, structure and recycling and the product reconstruction design scheme was obtained taking the contradiction matrix of TRIZ theory to resolve conflicts. Finally, the validity and feasibility of the proposed method were verified by taking permanent magnet synchronous traction machine as the research object.

    • Strength Analysis and Experimental Verification of Single Tooth Meshing of Large Module Pinion and Rack Transmission Pair
      CHEN Baojia; GONG Zongxing; XIAO Wenrong; CHEN Fafa; XIAO Nengqi; LIU Qiang

      Abstract:The service environment and operating conditions of the large modulus pinion and rack driven hoisting mechanism are complex,and the coupling between the system components is increasing day by day.In the alternating operation cycle of multi tooth-single tooth-multi tooth,the load-bearing stress of single tooth meshing is higher than that of multi tooth meshing.Therefore,it is necessary to analyze the changes of strength and stiffness of single tooth meshing in order to improve the accuracy of the research about the bearing capacity of pinion and rack pairs.Taking the Three Gorges ship lift as the research object,the working condition simulation test bench of vertical pinion and rack hoisting mechanism was built,six kinds of working condition were studied,and the contact strength and bending strength of pinion and rack hoisting mechanism were theoretically analyzed.Two kinds of stress and stiffness changes of single tooth during working period were simulated and analyzed by finite element software,and it was compared with theoretical analysis.The accuracy of the theory and simulation was verified by experiments,and the errors were all about 10%.The simulation results show that the meshing stiffness of the single tooth increases with the increasing angle and load,and the changing trend of the strength is consistent with it.

    • Research on Trajectory Tracking Control Method of Dual-arm Robot
      ZHOU Zhen; CUI Guohua; PAN Ying; HAN Jiabu

      Abstract:In order to solve the problem of grinding space limitation and low precision of workpiece in actual machining and improve the trajectory tracking effect of robot operation, a dual-arm robot trajectory tracking control method was proposed. Taking the hub grinding as the research background, PD control was adopted on the master-slave gripper robot to grip the grinding workpiece for controlling the position of tracking movement. The impedance control with a based position was used in the grinding robot to realize the force control and end position compensation and improve positioning accuracy. A simulation model was designed based on MATLAB/Simulink to verify the feasibility through the comparison between simulation results and finished experiment. The experimental results show that when the end of the manipulator is under the action of external interference force, it can track and correct the trajectory adaptively and meet the requirements of the trajectory tracking control of the dual-arm robot.

    • Research on Gait Planning of Cabin Inspection Robot Based on Hopf Oscillator
      SUI Xiang; ZHOU Ruiji; XU Linsen; LIU Jinfu; LONG Jie; LI Zelin

      Abstract:The cabin of ships and other marine engineering equipment is characterized by numerous equipment,restricted space and complex structure.Traditional manual inspection cannot overcome the problems of safety and efficiency.To solve these problems,the climbing mechanism of organisms such as inchworm was studied,and a multi-mode climbing robot for cabin inspection was designed by using negative pressure adsorption and electromagnetic adsorption in combination with bionic technology.The robot could move in small spaces and adapt to walls with different materials.A kinematics model of the robot was established based on modified D-H parameters,and the forward and inverse solutions of robot kinematics were solved.Compared with traditional gait control methods,a gait planning strategy based on Hopf oscillator was proposed with the gait analysis.Then,a prototype robot control platform was built,and a gait control comparison test was conducted to verify the stability of the gait planning of the multi-mode cabin inspection robot.The research expands a new idea for the research of new form inspection robot of marine engineering equipment such as ships.

    • Design and Experiment of Compound Actuator for Banana Stalk Clamping and Cutting
      OU Juji; ZHANG Rihong; HU Hongnan; HUANG Xinbin; ZHONG Jianming; HUANG Jiajun

      Abstract:The high-level and large-size characteristics of bananas bring great difficulty to picking.At present,the manual picking operation mainly needs to consume huge labor cost.A compound actuator for stalk clamping and cutting was presented.The compound actuator was mainly composed of clamping and swing cutting mechanism,electric chain saw,swing head base and hydraulic system.The driving power of clamping and swing cutting mechanism and crawler walking came from the hydraulic power system installed at the bottom of crawler truck.According to the clamping mechanical properties of banana stalk with a simulated diameter of 90~120 mm,the experiment results show that the banana stalk clamping and cutting composite actuator can be used to stably clamp the load weight of 60 kg.The heavier the load is,the greater the minimum clamping force requires,and the greater the regulating pressure of the corresponding pressure reducing valve is.Under the same load,the clamping force required for the larger diameter of banana stalk will also increase.The banana stalk clamping and cutting composite actuator is installed at the end of the adapted agricultural robot,then the clamping and cutting of the banana stalk and the hoisting of the whole string of bananas can be completed at one time.

    • Modeling of Spindle Thermal Error Based on MEA-NARX Neural Network
      SUN Ang; WANG Lishuang; XIE Xinlian

      Abstract:In order to effectively improve the accuracy of the thermal error prediction model based on nonlinear time series, the cluster number of fuzzy C mean clustering was determined by statistical test, and the key temperature measurement points were sorted and selected by combining the grey correlation analysis with different dimensionless processing. The thermal error prediction model based on NARX neural network was established; by setting the ranges of the input delay order, output delay order and the number of hidden neurons, the mind evolutionary algorithm was used to optimize the input and output delay order and the number of hidden neurons. Compared with the NARX neural network prediction model with randomly selected parameters, the prediction accuracy of the model is improved by 36.98%.

    • Research on the Control System of Automatic Winding Machine
      SUN Zhilong; JIA Limin; LIU Yong; LI Lijie; WANG Huazhen

      Abstract:Aiming at the phenomenon of low manual winding efficiency and poor machine winding effect in the closed loop structure winding in current market, a set of self-developed automatic winding machine control system was developed,by which winding automation and precise control of winding precision and tension could be realized. Using CC-Link, RS232 and RS485 bus technology, the control system was built through communication between PLC and various servo hardwares. The control system mainly revolved around the three functions of wire storage, winding and tension adjustment. The programming of the storage line function was completed by using Modbus protocol, the programming of winding function and tension stability control was completed by the UG motion simulation and PID control idea. The position relationship between the midline shuttle wheel and the storage wheel motor in the winding process was obtained, the effectiveness of the control system was proved by the prototype test.

    • Research on Unpowered Lowering System of Hydraulic Excavator Boom
      ZENG Xianyong; HE Wende; LIN Jiaqing; ZOU Xiumin; ZHANG Guoyong

      Abstract:In view of the problems such as fixed throttling area of throttle valve, long return pipeline high heating at valve ports, high energy consumption and explosive pipe used in the hydraulic excavator boom powered lowering system, measures such as increasing explosion-proof pipe valve, solenoid valve, pressure switch, controller and changing the function of multi-way valve were adopted, a hydraulic excavator boom unpowered lowering system with low heat, low energy consumption, stable start-up, simple structure, low cost and long service life was developed. The test results show that using the unpowered lowering system realizes energy saving and emission reduction, and the heat is reduced by nearly 50% compared with the powered lowering system, which reduces load for the heat dissipation system.

    • Adaptive Feed Control System for Micro-electrochemical Machining
      LI Lu; ZHANG Jianhua; GAO Shiping; GE Hongyu; YU Yao; DU Xinru; GAO Hong; YANG Qiuping

      Abstract:In order to achieve precise control of the micro-electrochemical machining gap, to achieve stable gap and even constant gap machining, the machining gap was modeled, and a micro-electrochemical machining feed adaptive control system was proposed and implemented. The embedded controller combined with the specific integrated circuit control structure was adopted, the software and hardware were designed to realize the gap control system and the processing experimental device, and the processing experiments were carried out with acid and alkaline electrolytes respectively, and the 400 μm and 600 μm micro holes were realized. The experimental results show that the designed micro-machining adaptive control system and experimental device can ensure a stable machining gap and meet the requirements of micro-machining technology.

    • Research and Development of Control System of Grinder Electrolytic Grinding Device for High Speed Steel Roll Material Grinding
      JIANG Jiatong; WU Huaichao; NIE Long; LI Jian

      Abstract:Aiming at the problem of repairing high-speed steel roll material, the control system of electrolytic grinding device for high-speed steel roll material was developed. Based on the machine tool of ordinary cylindrical grinder, S7 200 SMART series PLC was used as the controller to control the cathode feed system, electrolyte supply system and processing system. The hardware, software and human-computer interaction design of the control system of electrolytic grinding device for high-speed steel roll material were carried out. The control system has modular functions such as automatic tool setting, fault detection and so on. A fuzzy controller PI dual-mode control method with correction factor was proposed for machining gap control, and the MATLAB/Simulink simulation model was established. The results show that the control method has ideal effect, strong robustness and it can adjust the controller gain parameters. The algorithm was programmed into PLC, the machining gap control process with small steady-state error, small overshoot, fast response, and good stability were realized. The pre experiment was carried out to explore the relationship between machining gap and temperature on machining current. The results show that the machining current decreases with the increase of machining gap and increases with the increase of temperature.

    • Software Design for Universal Industrial Robot Teach Pendant Based on Shared Library
      YANG Liangliang; YE Jiabao

      Abstract:In response to the diversified market demand for industrial robots,a universal teach pendant software applied to the embedded Linux operating system was designed.Man-machine interface was designed based on QT development framework.According to the demand analysis and the working principle of the teach pendant,the motion control module,the code editing module of the robot language,the teaching reproduction module based on the robot language code,and the communication and data acquisition module were designed.In order to make the teach pendant software universal,shared library in Linux operating system was introduced into the software architecture.The code related to the robot algorithm was integrated into a replaceable shared library according to a common interface.Finally,combined with the swing arm welding robot and the SCARA robot mechanical body,the industrial robot control system was built and the operation test was carried out.The results show that the designed teach pendant software has friendly and functional man-machine interface,and can be applied to different industrial robots.

    • Design and Analysis of the Gripping Mechanism for the Press-fit Bearing of the End Cover Assembly of the Wheel Hub Motor
      YANG Luchao; SHEN Tingting; CHEN Xiao; QIU Zixue

      Abstract:The single machine press fitting efficiency of the end cover assembly of the wheel hub motor is low and the process is scattered.Based on analyzing the structure and press-fitting process of the end cover assembly of the wheel hub motor,a “bearing-end cover-oil seal” integrated press-fitting device was designed.In the press-fitting device,the bearing grasping mechanism used the friction between the O-ring and the bearing inner ring to grasp the bearing.A method for O-ring selection calculation and groove design using Lindley formulas and empirical formulas according to the required friction force was proposed.The prototype was trial-produced according to the simulation plan.The test results show that the designed bearing grasping mechanism can be used to realize the stable grasping and pressing of the bearing and the automatic separation from the bearing after pressing.

    • Optimal Design and Analysis of Mineral Material Gantry Frame for Direct-drive Machine Tools
      SONG Zengyu; PENG Jinmin; HU Gaoshang; ,YU Luojian

      Abstract:In order to process workpieces with a diameter of 320 mm and a height of 250 mm,a five-axis direct-drive compound machining center with mineral materials for the bed and gantry frame was designed while ensuring various contact dimensions.In order to reduce the weight of the machine tool and reduce its center of gravity,the mineral material gantry frame was designed to improve the modal performance and minimize the flexibility as the goal of topology optimization design,and then the multi-objective genetic algorithm was used to optimize the size of the topologically optimized gantry frame.And its dynamic and static performance was carried out simulation analysis and comparison many times before and after.Compared with the existing cast iron gantry frame in the market and the finally optimized mineral material gantry frame,the results show that the quality of the mineral material gantry frame decreases by 15.03%,the maximum deformation decreases by 8.7%,the maximum stress decreases by 56.68%,and the first order natural frequency increases by 23.45%.The optimized mineral material gantry frame is significantly better than the cast iron gantry frame support in terms of static and dynamic characteristics and lightweight.

    • Research on System Integration and Application of Loading and Unloading Unit of FANUC Robot Based on EtherNet/IP Industrial Ethernet
      CAO Jinjiang; GAO Shiping

      Abstract:Aiming at the disadvantages of troublesome construction and maintenance, difficult expansion of physical I/O hardware connection between loading and unloading unit equipment, an integration scheme of loading and unloading system based on industrial ethernet was constructed. The data communication between Rockwell PAC, FANUC CNC machine tools and FANUC robot equipment based on EtherNet/IP industrial ethernet was focused on, and the product processing flow, robot fixture quick change function and equipment loading and unloading program were analyzed. Through the built experimental platform, it is verified the correctness of the designed scheme, the software has stable performance and rich functions. The results show that: the loading and unloading unit based on Industrial Ethernet has the advantages of simple hardware connection, convenient maintenance, rich communication data and flexible function development.

    • Intelligent Temperature Control System of Low Pressure Casting Aluminum Alloy Wheel Hub Based on DSP
      ZHAO Yan; LI Yulong; ZANG Yong; CHEN Yegao; LU Wenlong

      Abstract:To realize intelligent control to the rapid solidification of aluminum alloy wheel hub in the solid-liquid phase solidification temperature range,an ARM+DSP control system was designed to predict the temperature of the casting by obtaining the current mold temperature and filling speed in real time,thus to control the cooling system.The temperature and pressure parameters were set by ARM in the man-machine interface,and the pressure and temperature data were calculated and processed by DSP.According to the feedback data,the opening and duration of water cooling and air cooling in the cooling system could be regulated,then the accurate control of the casting temperature could be realized.Therefore,the wheel hub of low-pressure casting could solidify rapidly and sequentially in the solid-liquid phase solidification temperature range with better surface quality and mechanical properties.Thus,the intelligent control of the production of continuous low pressure casting aluminum alloy hub is realized.

    • Research on Flow Regeneration and Energy Recovery and Energy Saving of Drilling and Digging Integrated Excavator
      LIU Xiaoqiang; SHAN Genli; LI Bin

      Abstract:The use of a multi-functional excavator for complex pipeline construction brings great convenience to pipeline engineering. During excavation and drilling operations, the gravitational potential energy of the boom is converted into hydraulic energy and flows back to the oil tank at the overflow valve to form overflow loss. A flow regeneration loop was set in the hydraulic oil circuit of the boom to improve the action rate. The valve control system was used to recover the gravity hydraulic potential energy dropped by the boom, and the quantitative motor was driven by the hydraulic energy recovered in the accumulator to motivate the generator to generate electricity. The electric energy was stored in the battery to provide electric energy for other electrical appliances of the excavator. Using AMESim software for hydraulic simulation, compared with existing excavators, recovering the hydraulic energy of the boom descent greatly improves the energy utilization rate of the system, and the flow regeneration improves the movement speed of the excavator. The research results show that the energy recovery efficiency of boom descent is about 40%.

    • Mathematical Model Analysis of the Influence of Hone Radius on Radial Pitch Diameter Difference
      REN Jie; LI Tingting; MENG Yu; ZHANG Rui; YAN Xianguo

      Abstract:As the most important load-bearing component in the aircraft, threaded connection has a significant impact on the safety of the aircraft. Therefore, it is very important to manufacture high-quality internal threads on Al7075, a commonly used material for aircraft manufacturing. As an important parameter for evaluating the quality of internal threads, the radial pitch diameter difference has a great influence on the quality of internal threads. The hone radius affects the processing quality of the internal thread.In order to study the influence of the hone radius on the radial pitch diameter difference of Al7075 tapping, a quasi-static mathematical model of tapping was established for simulation, and it was verified by experiments. The results show that the model can be used to effectively predict the changing trend of the radial pitch diameter difference; the radial pitch diameter difference first decreases and then increases with the increase of the hone radius, and the smallest radial pitch diameter difference is obtained at the bone radius is 10 μm.

    • Analysis of Starting Characteristics of Hydraulic Circuit for Monorail Lifting
      DU Wei; LUO Yu; LUO Yanlei; MU Hongyun; REN Xiaode

      Abstract:With the development of mining equipment,the increase of mining quantity puts forward higher requirements for the performance of monorail crane,which is widely used in recent years.Taking the hydraulic circuit of monorail lifting as the research object,the influence of the damping hole on the motor starting of the hydraulic brake cylinder was analyzed.The mathematical model of the system was established,and the results were simulated in Simulink,then the simulation test was carried out by AMESim.The results show that setting a damping hole in the inlet road of the brake hydraulic cylinder has a delayed effect on the start of the motor,which can make the motor start quickly when it has a large enough start torque and prevent the motor start torque from being insufficient due to the rapid release of the brake; compared with the loop with no damping hole,the hydraulic impact is weakened,and the delay effect is more obvious with the decrease of the damping hole diameter.

    • Evaluation of the Roundness Error Based on Circle Segmentation Algorithm
      LI Guowen; XU Ying; LIU Yang; WANG Sainan; ZHANG Qian; AN Dong

      Abstract:Accurate evaluation of roundness error is of great significance for improving machining accuracy and ensuring working accuracy of parts.Aiming at the problems of low evaluation accuracy of roundness error and slow calculation speed,a roundness error evaluation algorithm,namely circular segmentation algorithm,was proposed.A new mathematical model was established.The circle segmentation algorithm was combined with the geometric judgment of the minimum containment area method to evaluate the roundness error.The least squares circle center was used as the initial circle center,and a circle was made with a certain radius.After iteration,the position of the real-time circle center was searched,and then the geometric structure of the intersecting chords was used to judge,finally the circle center of the minimum containment area was obtained.This method did not need to meet the assumption of equal interval sampling and small deviation.After algorithm verification,the roundness error was evaluated and compared.The results show that the roundness error evaluated by using this method has high accuracy,fast calculation speed and good stability.

    • Simulation Analysis of Pilot Electro-Hydraulic Proportional Synchronous Control of Monorail Hoisting Motor
      ZHANG Li; MU Hongyun; LIU Yao

      Abstract:In order to overcome the unbalanced load lifting and load fluctuation of monorail crane and improve the safety of equipment,a Fuzzy-PID synchronous control system for monorail crane motor was proposed.The hydraulic working principle of the system was analyzed,and the master-slave synchronous control strategy was selected.Modeling in AMESim and Simulink was completed.The joint simulation was carried out and compared with PID to analyze the synchronization and robustness of the system.The simulation results show that it is feasible to use Fuzzy-PID for monorail hoisting motor.Compared with PID,it has the advantages of fast response,small overshoot and good robustness.When the Fuzzy-PID is used under eccentric load,the system reaches a stable speed in 0.8 s,which is 42.1% higher than that of PID; the maximum synchronization error is 35 r/min,which is 27.1% lower than PID; after stabilization,the synchronization error is 0.6 r/min,which is 40% lower than PID; when the load fluctuates,the system reaches a stable speed in 0.4 s,which is 42.9% higher than that of PID; the maximum synchronization error is 13 r/min,which is reduced by 9% compared with PID.Therefore,Fuzzy-PID can be used to effectively solve the unbalanced load start and load fluctuation conditions of lifting motor,ensuring the stable,synchronous and safe operation of monorail lifting.

    • Three-Dimensional Dexel Model Simulation and Verification of Cylindrical Gear Hobbing
      ZHANG Huan; YU Li; WANG Jizhang

      Abstract:Aiming at the problem of hobbing simulation based on solid modeling technology,a three-dimensional Dexel model simulation method of cylindrical gear hobbing was developed.The kinematics model of cylindrical gear hobbing was studied.According to the geometric parameters of hob and gear blank,the triangular mesh model was created and transformed into the Dexel model in the engine.At the same time,efficient CWE calculation and geometric simulation of undeformed chips were carried out by Delaunay triangulation and Alpha shape reconstruction.The bevel cutting model was used to calculate the force distribution of all meshing nodes at each time step.Finally,Liebherr LC500 gear hobbing machine was used to verify the proposed simulation method,and the rotating dynamometer and Kalman filter were combined to compensate the structural dynamics,so as to measure the cutting force accurately.The results show that the proposed method can be used to accurately predict the three-dimensional force distribution of discrete nodes along the edge of hobbing,and the prediction error (root mean square and standard deviation) is between 4% ~ 12%; when the cutting conditions change,the axial and lateral cutting forces can still be accurately predicted,which is helpful to further improve the efficiency and accuracy of hobbing simulation.

    • Analysis of Influence of Clearance Ratio on Bearing Characteristics of Sliding Bearing of Fuel Pump
      GU Guangxi; GUO Yinhao; WANG Zhengrong

      Abstract:In view of the problem that the sliding bearing of fuel gear pumps is prone to wear due to the thin oil film thickness under high load and high speed conditions, considering that the clearance ratio is the main factor affecting the minimum oil film thickness of the sliding bearing, the sliding bearing of a fuel pump was taken as the research object, the bearing capacity, minimum oil film thickness, pressure and temperature distribution under different clearance ratios were analyzed by PumpLinx software. The flexible deformation of the gear shaft of the fuel pump was analyzed. Then the relationship among the clearance ratio of the sliding bearing, the minimum oil film thickness, and the bearing load-bearing capacity was analyzed under the two working conditions of the minimum and maximum speed. Besides, the distributions of temperature, circumferential and radial pressure of the bearing were analyzed. The results show that the bearing capacity increases with the decrease of oil film thickness under the same clearance ratio, the decrease of the clearance ratio, or the increase of the rotating speed. In addition, regardless of the pressure distribution or temperature rise, it is the best when the clearance ratio between the gear shaft and sliding bearing is the smallest.

    • Research on Buckling Instability Deformation of Rubber Balloon of Bladder Accumulator
      DUAN Chenghong; WANG Bo; LUO Xiangpeng; LI Fangyan

      Abstract:The bladder accumulator stores energy and stabilizes pressure changes in the form of compressing gas inside the rubber balloon during operation.Based on the ideal gas state equation and Mooney-Rivlin hyperelastic constitutive equation,the eigenvalue buckling analysis and the nonlinear post-buckling analysis of the finite element model of the fluid cavity of the bladder accumulator were carried out by linear perturbation and dynamic explicit simulation method.The results show:under the action of a uniform hydraulic load,the rubber balloon shows three pits deformed,which is consistent with the deformation in the experiment,indicating that the reason for the deformation of the three pits is buckling instability of the rubber balloon;the dynamic explicit simulation method solves the problems of poor calculation convergence and low calculation efficiency in the large deformation of rubber,and provides a good simulation method for the large deformation simulation of the three-dimensional solid model of rubber materials; the volume of the fluid cavity model of the rubber balloon is approximately inversely proportional to the pressure in the cavity,which is consistent with the ideal gas adiabatic equation,indicating that the use of fluid cavity to simulate the internal gas cavity of the rubber balloon is reliable.

    • Modeling and Simulation of Wheel Brake System Accumulator for Civil Aircraft
      CHEN Guohui; DENG Weilin; MA Xiaojun

      Abstract:Based on civil aircraft operation scenario and airworthiness regulations, a requirement-oriented forward design method for civil aircraft system was proposed. Taking the accumulator brake of aircraft wheel brake system as an example, the needs of stakeholders was analyzed to define the requirements of accumulator brake system, then the process of accumulator brake was analyzed and calculated. The general simulation software of accumulator brake system was established based on MATLAB/Apps platform, and the requirements of accumulator brake were validated based on model. Finally, a multidisciplinary integrated model of wheel brake system was established based on Simscape and Simulink platform for the collaborative simulation of the accumulator brake system, and the requirements of accumulator brake were verified based on model. By using the forward design method constructed based on requirement, the requirements definition is completed in the preliminary design phase,the validation and verification of requirement is completed through the model, reducing the risk of system development.

    • Rolling Bearing Fault Diagnosis Based on VMD Hybrid Domain Feature and SSA-SVM
      CHEN Weiwang; LI Junxia; ZHANG Wei

      Abstract:Early fault signals of rolling bearings are easily interfered by noise,and fault impact components are difficult to be extracted and fault identification is difficult.In order to extract characteristic parameters from multi-angle fault bearing vibration signals,the vibration signals were decomposed into several intrinsic mode functions (IMFs) using variational mode decomposition (VMD),and IMF components were screened based on envelope entropy,correlation coefficient and kurtosis.The time domain and frequency domain features of selected IMF,VMD energy entropy of signal and energy ratio of each IMF were extracted to form feature vectors,and the fault information was reflected from time domain,frequency domain and energy perspective.The sparrow search algorithm (SSA) was used to optimize SVM parameters and determine the optimal parameters to overcome the problem of parameter selection.The sample feature vectors were input into SSA-SVM for fault classification.The experimental data of bearing faults show that the average accuracy rate of fault identification by this method is above 98.71%.Compared with single domain feature,this method has better recognition effect on fault type and damage degree.

    • Reliability Analysis of Spindle System of A Heavy-duty CNC Machine Tool Based on Fuzzy Fault Tree
      CHEN Hongxia; WANG Jihua; MA Aibo; GUO Chuncheng; LI Hongyue

      Abstract:In order to improve the reliability of the spindle system of CNC machine tools and find out the weak links of the spindle system,taking the spindle system of a heavy-duty CNC horizontal milling and boring machine as the research object, a fault tree with the spindle system failure as the top event was established. Due to the limitation of time and cost,it was difficult to obtain the accurate value of the failure rate of basic events. Therefore, combined with expert judgment and fuzzy set theory, the expert opinions were summarized into trapezoidal fuzzy numbers,and the occurrence probability of basic events was determined. Qualitative and quantitative analyses of fault tree were carried out,and the importance of basic events was calculated. Finally, the critical failure factors that affected the system were determined through the ranking results of the importance of the basic events.

    • Research on Gearbox Fault Diagnosis Based on CEEMDAN Adaptive Wavelet Noise Reduction and Convolution Neural Network
      CAI Chaozhi; BAI Jinxin; CHI Yaolei; ZHANG Zhonghang

      Abstract:Accurate fault diagnose of gearbox under noise condition is a difficult problem in gearbox fault diagnosis. In order to solve this problem, the noise reduction method of decomposing and reorganizing complete ensemble empirical mode decomposition with adaptive noise analysis (CEEMDAN) by adaptive wavelet was adopted, and the convolution neural network based on inception(BICNN) was put forward to extract the basic digital characteristics of the reconstructed signal and long short-term memory(LSTM) was adopted to extract the correlation features among the features extracted by BICNN.The method was used to study the fault diagnosis of the gearbox. The diagnosis results show that the proposed method has high anti-noise ability, and it can still obtain 99.63% training accuracy when the gearbox is disturbed by -4 dB noise.

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