Abstract:Shock response spectrum technology is the important technical means for simulating complex impact environments in laboratory environment, so it is important to study the synthesis timedomain waveforms of shock response spectrum. The relative displacement model of the shock response spectrum was constructed. The shock response invariant method was used to design the digital filter, and the calculation of shock response spectrum was completed.Taking the sinusoidal fundamental wave as the basic waveform of the synthetic fundamental,the expressions of the fundamental waveform parameters were determined, and the amplitudes were corrected by iteration. The simulation results show that the shock response spectrum calculated by using the above method can meet the requirements of the test specification within the tolerance range of the target spectrum. The method can be widely used in shock test and has certain promotion value.

Abstract:A highperformance analog drive system for DC brushless motor with complex programmable logic device (CPLD) as core was described. Full hardware circuit design, trapezoidal commutation and PWM speed control strategies were adopted, so it had higher response characteristics.For the analog drive system,the commutation torque ripple of the motor under four PWM modulation methods were derived and calculated. An improved PWM speed control strategy was proposed, namely the system was controlled by switching different PWM modulation modes according to different duty cycles.The torque ripple values of the motor which was controlled by improved PWM speed control strategy and the traditional PWM speed control strategy were compared. An experimental platform was built, and the commutation torque ripple of the motor with the improved PWM speed control strategy under different duty cycles conditions was tested. The correctness of the improved PWM speed control strategy was verified.

Abstract:Aimed at the inconvenience of manual tuning parameters of PID controller commonly used in servo system, machine learning algorithm and fuzzy control were researched. The back propagation (BP) algorithm and design methods of fuzzy controller were emphatically analyzed. A PID parameter tuning method based on machine learning algorithm and fuzzy control was proposed. The learning ability of BP neural network was used to get the system model, and the PID parameters were predicted by combining with the fuzzy control, which were verified on the experimental platform. The results indicate that the PID parameters obtained by using machine learning and fuzzy control have better control effect. By using this method, it can avoid manual tuning of PID parameters and save a lot of time.

Abstract:In order to solve the complexity and low efficiency of the integral calculation method in the curve smoothing of large impeller blades, the curve smoothing method based on shear jerk and local energy was studied. The smoothing requirements of the impeller blades were analyzed. The shear jerk global detection model and local energy smoothing model for the nonsmooth point of blade curve were established. The nonsmooth point detection and smoothing for the discrete points on the shaft curve and cover curve were carried out by using the established models. After smoothing, the maximum shear jerk of the shaft curve and the cover curve are reduced by 41.3% and 39% respectively, which improves the smoothness of the blade curve.

Abstract:AlSi10Mg samples were formed by selective laser melting (SLM) process, the microstructure and mechanical properties of the samples were studied. The AlSi10Mg sample was printed by AFSM260 selective laser melting machine produced by a company, the sample was analyzed by using microhardness tester, optical microscope, scanning electron microscope and XRD diffractometer, and its micro hardness, structure morphology, element distribution and phase composition were obtained.The directional growth of the eutectic structure caused by the unique forming method of SLM makes the anisotropic microstructure of the sample in the horizontal and vertical directions,but the microstructure on the same section presents a gradient structure from the boundary of the molten pool to the inside,which can be divided into three regions, namely, coarsegrained zone, heataffected zone, finegrained zone.The α-Al matrix size, average eutectic Si width and eutectic structure content in the transverse and vertical sections of each zone show a downward trend.The hardness of the sample is significantly larger than that of the conventional ascast sample,but the transverse and longitudinal sections are not much different.The SLM-formed AlSi10Mg sample has excellent hardness properties and a small formed microstructure, which is mainly due to the high cooling rate of SLM forming.

Abstract:By using the methods based on pulseecho method, A-scan method, longitudinal wave method, single probe method and immersion method, the longitudinal sound velocities of aluminum and copper chip substrate were measured. The two methods of changing the sound path based on transducer movement and based on reflecting undersurface change were respectively used to calibrate the sound velocity in water, and the measurement error of the system was 0.13%. Adopting the method of changing the sound path based on reflection interface change, the sound velocities of aluminum substrate and copper substrate were measured. Within the 90% confidence probability interval, the sound velocity of aluminum and copper substrate are (6 375.97±29.97)m/s and (4 655.70±28.24)m/s respectively. The simulation results are similar to the measurement results, which shows that the measurement method has high accuracy. The measured sound velocity can be used to study other physical characteristics of the chip as well as the bonding quality of the connection and internal interface of the chips.

Abstract:The improvement of milling processing efficiency and machining accuracy will require the improvement of milling machine processing speed. With the development of magnetic levitation technology, highspeed magnetic levitation electric spindle has become a key component of milling machine. The magnetic levitating motorized spindle rotor system has strong gyro coupling effect at high speed operation, and its excessive coupling effect makes the stability region of high speed milling narrow and even makes the milling system unstable. So, a control method based on PD controller for modal decoupling-state feedback was proposed. By using the method, the coupling between the translational mode and the rotational mode of the rotor system and the coupling between the rotational modes in the two directions were decoupled,the proportional and damping coefficients of the controller were independently adjusted to reduce the influence of the gyro coupling effect on the stability region of the magnetic levitation milling system, and the stability region of milling was improved. The effects of modal decoupling-state feedback control gyro coupling effects on the stability of the milling region based on PD controller were studied by simulation. The results show that by using the modal decoupling-state feedback control technology based on PD controller, not only the effect of gyro effect on milling stability type can be reduced, but also the stability area of milling can be improved.

Abstract:In view of the low calculation accuracy for laser cutting speed when cutting stainless steel plates, the stainless steel material characteristics were analyzed, MATLAB software was used to fit the data of specific heat capacity and thermal conductivity at different temperatures, and the functional relationships between specific heat capacity and temperature, thermal conductivity and temperature were obtained respectively. Then, the energy transfer law in the process of cutting stainless steel plate by laser was analyzed, and the heat balance equation was established in combination with the law of conservation of energy, i.e. the total energy absorbed by the material was equal to the sum of the energy absorbed by heating the slit material to the melting point, the energy lost in heat conduction and the latent heat of melting of the material, and the functional relationship between cutting speed and other process parameters was deduced.Finally, an experiment was carried out on a laser cutting machine. The cutting experiment results show that the calculated cutting speed is in good agreement with the optimal cutting speed obtained by the experiment, and the method can be used to guide the actual processing.

Abstract:In the process of precision and ultra-precision machining, thermal error of CNC machine tool is a main error source that affects machining accuracy, and thermal error compensation technology is the most economical and effective method to reduce thermal error. For the prediction accuracy problem of thermal error compensation prediction model, a nonlinear combination prediction model was proposed. The single prediction model was screened by using the grey correlation method, and the selected single prediction models were combined linearly based on different optimization criteria. The generalized regression neural network was used to combine the linear combination model, and the nonlinear combination prediction model was obtained. The error prediction results show that compared with the typical BP neural network prediction model, the nonlinear combination prediction model has higher prediction accuracy, and the maximum error decreases from 4.78 μm to 0.7 μm.

Abstract:Based on the LabVIEW software development platform, the detection and control system for the giant magnetostrictive actuator (GMA) was designed in order to control the GMA used in the precision control of sliding bearings. The GMA was used to control sliding bearing base in this control system. The results show that by controlling the frequency and amplitude of the output voltage of the programmable power supply, the expansion of the GMA can be effectively controlled, and the position of the test base can be accurately controlled. The effectiveness of the GMA test system is proved. It provides reference for controlling the bearing clearance by using the GMA to suppress the rotor vibration.

Abstract:The position servo system has higher and higher requirements on response speed, positioning accuracy and antidisturbance performance. Traditional PID control is easy to implement, but it depends on the object model and its performance is limited, so it is difficult to meet the high requirements. Sliding mode control does not depend on the object model and has strong applicability. Therefore, a fuzzy adaptive sliding mode control method for position servo system was proposed, by which the exponential reaching rate was adaptively adjusted. Taking the position servo system as the object, the simulation and experiments for position control and antidisturbance performance were carried out by using the methods of PID control, sliding mode control and fuzzy adaptive sliding mode control. The results show that the fuzzy adaptive sliding mode control is superior to the PID control in fast position and antidisturbance performance; compared with the ordinary sliding mode control, the fuzzy adaptive sliding mode control has better dynamic performance. Therefore, the proposed fuzzy adaptive sliding mode control has better applicability and certain application value in those applications where need fast response and strong antidisturbance performance.

Abstract:In the actual operation of highspeed motorized spindle, there are problems such as high spindle heat and temperature rising inside the spindle, which lead to thermal deformation of the spindle and then affect the machining accuracy of motorized spindle. In order to solve the above problems, taking a certain motorized spindle as the research object, and the cooling ability of the cooling system was explored by combining simulation and experiment. The thermal characteristics of motorized spindle were described. The finite element simulation results of spiral and circulating cooling system were analyzed. The cooling ability experiment was carried out to verify the simulation results. The results show that the overall cooling effect and cooling rate of the spiral cooling system under steady state are better than that of the circulating cooling system. The results provide some technical references for the design, optimization and development of motorized spindle.

Abstract:Due to the electrohydraulic servo testing machine has strong timevarying and nonlinearity, and load characteristics often change, the system has great parameter uncertainty.When the parameters of the controlled system change,it is difficult to obtain satisfactory control effect by using the traditional PID control with fixed parameters. If the parameters are adjusted again, the complexity of the control operation will be greatly increased.In order to solve this problem, the design scheme of the controller with quantitative feedback theory (QFT) was used to control the electrohydraulic servo testing machine. QFT controller is designed for system uncertainty.For the system with strong control uncertainty, the controller has unique advantages; the QFT controller can also “tailor” the control performance of the system in different frequency bands. The electrohydraulic servo testing machine with parameter uncertainty was identified, and QFT controller design and simulation were carried out on the system model. The results show that the designed QFT controller has higher control precision and stronger robustness than the PID controller when the working condition is changed.

Abstract:To improve the quality of remanufactured crankshaft blank, a quality evaluation model for remanufactured crankshaft blank was established, and its remanufacturing performance was systematically analyzed from three aspects of failure, economy and material. A failure evaluation method based on extension method was proposed. The classical domain of failure index was set according to expert experience knowledge, and the evaluation value obtained by expert evaluation method was used as extension evaluation matter element. The preliminary classification of crankshaft was established by the correlation degree between synthesis function and recovery decision. On this basis, the crankshaft to be remanufactured was evaluated comprehensively in terms of equipment cost and time cost, and the crankshaft with excessive remanufacturing cost was recycled. The crankshaft whose material property index was higher than the threshold value was recycled, and the rest was discarded. Finally, five decommissioned crankshafts were selected for application research. The experimental results show that the recycling method adopted is consistent with the actual engineering experience, and the crankshaft is evaluated in stages and in an allround way, which is convenient for enterprise decisionmaking.

Abstract:The thrust fluctuation of permanent magnet linear synchronous motor (PMLSM) is closely related to it’〖KG-*2〗s input current. In order to minimize the current error, a rotation angle compensation algorithm based on Park transformation was proposed, and a PMLSM double closedloop slidingmode variable structure control (SMC) system was established based on this algorithm. For the chattering problem introduced by SMC controller and the inherent disturbance of the system, the disturbance thrust observer was designed. The MATLAB/Simulink cosimulation results show that the proposed strategy can be used to effectively reduce current error and motor thrust fluctuation.

Abstract:A air supply system which could supply compressed air with constant pressure and humidity was developed. The system was mainly composed of clean air units, pressure subsystem and humidity subsystem. The proportional flow valve and throttle valve of the system were selected. The humidity subsystem including dry air branch and wet air branch was designed. The humidity of compressed gas was controlled by changing the flow ratio of dry air branch and wet air branch while maintaining constant pressure through PID closed loop. The experiment shows the system can keep constant pressure and humidity in the range of 0~0.2 MPa and atmospheric pressure dew point -15~20 ℃. The maximum flow rate of air supply can reach 79.6 L/min (ANR). This system provides reference for the development of constant pressure and humidity gas supply system.

Abstract:In order to solve the problems of poor antinoise performance and low precision existing in the current rapid calibration method for monocular camera of laser cutting vision system, an improved camera selfcalibration method based on nine dots was proposed. The theory of the algorithm was analyzed and verified by experiment.The improved nine dots calibration algorithm was compared with the existing monocular camera fast calibration algorithm by experiment. The results show that the improved nine dot calibration algorithm has better antinoise performance and higher accuracy than the existing monocular camera fast calibration algorithm.

Abstract:Using new intelligent manufacturing system can improve the production efficiency and product quality, and improve the adaptability and flexibility of the supply structure of manufacturing industry.Taking the Internet of Things (IoT) as the core, an intelligent manufacturing system of the IoT based on Niagara under the Unity 3D environment was proposed.Based on the threelayer architecture of the IoT, software secondary development was carried out,the compatibility among various module protocols was realized.Then the intelligent manufacturing was realized.

Abstract:Based on the theory of fluid mechanics, the factors of mechanical power loss of an internal gerotor pump were analyzed and the mathematical model of the mechanical power loss of this type pump was established. The internal gerotor pump mechanical power loss was calculated and tested,and the correctness of the mathematical model was proved.It provides a theoretical basis for studying the power loss of the internal gerotor pump.

Abstract:The proportional valve is the core component of the adjustable damping shock absorber, and its dynamic characteristics directly affect the damping adjustment effect of the shock absorber.A proportional valve for shock absorber was proposed. The structure and working principle of the shock absorber were introduced. The dynamic characteristic model of the valve was established, and its dynamic characteristics were simulated and analyzed. The effects of the excitation voltage, load differential pressure, motion damping coefficient and the mass of the spool and armature on the rising time and response time of the spool were studied. The results show that the higher the excitation voltage is, the smaller the load pressure difference is, the smaller the damping coefficient is, the shorter the proportional valve response time and the spool rising time are; the mass of the spool and armature assembly has less influence on the dynamic time domain characteristics of the proportional valve.

Abstract:In order to solve the coupling vibration problem of the fan impeller during rotation, the centrifugal fan impeller was taken as the research object, κ-ε turbulence model and vibration mechanics theory were used to analyze the flow field and mode around the impeller, and the distributions of the pressure and velocity in the internal flow field of the centrifugal fan under different rotating speed were obtained. The results show that the large compression area is distributed around the fan outlet, the center speed of the impeller is small, and the radial speed increases gradually; with the increase of the rotating speed, the first four modes of the impeller decrease gradually, and the last two modes increase gradually. The conclusion provides a reference for the working condition and optimal design of the fan impeller.

Abstract:Railway transportation vehicles are developing towards highspeed and light weight. The vehicle body bears complex alternating loads, which greatly increases the risk of fatigue fracture of the vehicle body structure. In order to explore the influence of vehicle body structure vibration on the safety of vehicle structure, ANSYS Workbench was used to simulate the vehicle body mode. Combined with the modal test data of the EMU body in the service environment, the firstorder diamond (8~9 Hz), firstorder vertical bend (12~13 Hz), firstorder transverse bend (15~16 Hz) and firstorder torsion (17~18 Hz) model frequencies were extracted, and the vehicle finite element model was compared and modified. The measured data of the measured load spectrum were processed by using the rain flow counting method, and the load spectrum rain flow counting matrix was obtained. Based on the modal analysis, the harmonic response analysis was carried out, and the frequency response functions in the above different modal frequency ranges were obtained. The nCode fatigue simulation software was used to simulate the fatigue strength of the vehicle body, and the fatigue damage of the vehicle body in different frequency range was obtained. Miner linear cumulative fatigue damage theory was used to evaluate the fatigue damage of vehicle body. The results show that the frequency band near the firstorder diamondshaped mode (8~9 Hz) of the vehicle body causes the most damage to the vehicle body, and the damage location is near the intersection of the vehicle hook and bolsters.

Abstract:Based on the finite element analysis method, the contact state of the tooth pairs during the initial meshing of the cycloidal pin wheel was studied. By considering the profile modification of the cycloidal pin gear pair and the modeling accuracy of the cycloidal gear tooth profile, the threedimensional model of the cycloidal pin wheel pair was established by using the APDL language provided in ANSYS. Then, by considering the finite element mesh quality and the computational efficiency of the finite element model, the finite element model was generated by using the VSWEEP command and the mesh was refined locally. Finally, by considering the actual working condition of the cycloidal pin wheel, the contact pair and boundary conditions of the cycloidal pin wheel were established. The analysis results show that there are 6 teeth in the initial meshing moment of the cycloidal pin wheel to participate in the force transmission. The first contact tooth is the 6th tooth, and the deformation of the cycloidal tooth and pin hole in the vicinity of the meshing tooth pairs is relatively large.

Abstract:Taking the hydraulic system of the master cylinder of a fine punching machine as the research object, the working principle of the hydraulic system of the fine punching machine was analyzed, the hydraulic system of the original master cylinder was improved, and the speed regulating module was added. The mathematical model of the accumulator was established, and the main parameters affecting the performance of the accumulator were theoretically found. The simulation model of the master cylinder hydraulic system of the fine punching machine was established by using AMESim software, and the influence of the main parameters of the accumulator on the punching frequency were analyzed.The HCD simulation model of the speed control valve module was established. The influence of the main parameters on the dynamic performance of the speed control valve was studied. The results show that the accumulator preinflation pressure, volume and interface size have a great influence on the punching frequency of the fine punching machine;when the initial opening amount of the pressure reducing valve is 5 mm and the orifice size is 2 mm, the dynamic performance of the pressure reducing valve is better.

Abstract:In order to improve the production efficiency of camshaft, the facility layout of traditional camshaft production line was optimized based on genetic algorithm. Taking the lowest logistics cost of camshaft production line as the objective function, the total length, width and the minimum distance between equipments as the constraints, the mathematical model of camshaft production line was established, and the optimal solution was obtained by using MATLAB software. According to the obtained layout solution, the machine tool layout model of camshaft workshop was simulated by using Flexsim software. The results show that the daily output of camshaft increases obviously, the logistics cost is decreases after the facility layout is optimized, and the expected target is achieved.

Abstract:Taking a series of steel round spring of a fast metro vehicle as the research object, the fatigue life prediction analysis was carried out. The finite element model was established by using finite element analysis software ANSYS, and the stress analysis under the maximum working load was carried out. The dynamic simulation software SIMPACK was used to establish the dynamic model of the fast metro vehicle, and the longitudinal, lateral and vertical vibration displacements with time of the spring were analyzed. Using the fatigue cumulative damage theory, taking the spring stress and load spectrum as the input, based on the fatigue life special simulation software FE-SAFE, the fatigue life of the spring was analyzed. The results show that the inner side of the second ring of the fast metro vehicle is the most stressful part, the maximum stress is 1 294.19 MPa, and the fatigue life is about 1 945 924 times, which is in line with the actual situation of a series of steel round springs of a fast metro vehicle.

Abstract:The oil drain valve removes air and heat in time in hydraulic fully variable air distribution system. Its performance affects distribution performance of hydraulic fully variable air distribution system. The mathematical and physical modeling of the drain performance of the new drain valve, namely, the drain time and the drain quality, was carried out. Using dynamic mesh 6DOF technique combined with single factor test, the influence of inlet pressure, valve opening, valve ball mass, preload force and spring stiffness on oil drain performance was studied. The single factor test reveals the influence law of each parameter on oil drain quality and oil drain time, and verifies the correctness of the mathematical physical model.

Abstract:Taking the headstock of 140 kN continuous drive friction welder as the research object, the static and dynamic characteristics of the spindle box were analyzed by using the finite element analysis software. In order to improve the comprehensive mechanical properties of the headstock and realize material rational use of the spindle box, the central composite experimental design was carried out with seven structural parameters such as the wall thickness of the box as design variables. According to the obtained data results, the response surface model of the spindle box was established based on Kriging interpolation method, and the sensitivity analysis of each design variable was carried out. The optimization design of the headstock was completed by using multiobjective genetic algorithm, the spindle box had a weight reduction of 16.6%, achieving a lightweight design of the welder. After verifying the fitting accuracy of the spindle box response surface model, it was verified that the combination of CCD experiment method and Kriging interpolation method could be used to effectively and accurately complete the establishment of the spindle box response surface model. Therefore, this optimization method can be applied to the design of other types of machine tool parts.

Abstract:Aiming at the complex and cyclical variation of the internal fluid domain structure of the twinscrew compressor,a numerical simulation method for the flow field simulation of the 5~6 tooth twin-screw compressor was proposed.In the method,Scorg software and Pumplinx software were used to jointly analyze the flow field of twinscrew compressor,the negative volume phenomenon of moving mesh was avoided,and the problem of defining the negative and positive rotation modes by writing complex UDF functions was solved.The simulation results show that the fluid pressure acting on the rotor gradually increases from the inlet to the outlet in the axial direction,the compression and exhaust areas with higher pressure and the lower pressure suction area are bounded by the contact line,the pressure changes fluctuationally;the temperature change is non-steady-state,and the closer it is to the exhaust port,the more severe the change.The temperature and pressure of the twin-screw compressor outlet were tested.The test results show that the simulated data agree well with the experimental data.The research provides reference for the design and in-depth study of screw compressors.

Abstract:When the landing speed of the aircraft is fast,the rapid compression of the oilgas buffer will cause the pressure surge inside the buffer and efflux phenomenon at the damping hole.In order to reduce the pressure inside the buffer and the flow velocity of oil through the damping hole, taking the oil inlet velocity, the hole length, the hole diameter and the chamfer of the damping hole as the research object, the variation characteristics of the pressure and flow velocity in the buffer caused by the changes of various factors were analyzed by using the single factor method. Simulation calculation was carried out by using Fluent software. The results show that the greater the inlet velocity of oil is, the greater the pressure inside the buffer and the flow velocity are. The hole length has little influence on the pressure inside the buffer and more influence on the flow velocity of the oil in the damping hole; with the decrease of the hole diameter, the pressure inside the buffer and the flow velocity of the oil in the damping hole increase continuously;the chamfer has little influence on the pressure inside the buffer, but it is useful for reducing the flow velocity of the oil in the damping hole. The research results can provide reference for the optimal design of buffer.

Abstract:The optimum oil film thickness for slipper is an important factor affecting the volumetric efficiency and life of the swashplate piston pump.In order to improve volumetric efficiency and service life of piston pump,an intensive study on the design method for the optimum oil film thickness for slipper was conducted.The theoretical formula of the optimum oil film thickness was gotten by derivation.Simulink simulation software was used to build a simulation model to obtain the optimum oil film thickness for slipper.On this basis,the factors affecting the value of the optimum oil film thickness were analyzed deeply.Furthermore,the result was applied to the realistic product for test assessment.The experimental results confirm the correctness of the theoretical result,indicating that an effective method was provided for the design of optimum oil film thickness for slipper.This method was applied to 6 types of product and the reasonable range of the optimum oil film thickness was summarized.It provides reference for the design of optimum oil film thickness for slipper.

Abstract:The welding robot inevitably produces arc force, which affects the welding stability to some extent. In order to solve this problem, 3R welding robot model was built in SolidWorks, the influence of arc force on the welding torch in the welding work was analyzed to reveal its dynamic characteristics in the welding process, to explore the relation between the end welding torch operation stability and welding area arc force. Connecting with the complex working condition, multiple sets of electric arc force with different size, nature and frequency were selected to make simulation, to find the link between the different arc force and the welding torch movement stability. The research results show that the disturbance to the welding torch from the arc force with different size, different properties and different frequencies has certain regularity, especially the change of frequency; when the welding power frequency tends to 20 Hz, the welding torch chattering is unusually intense, resonance phenomenon occurs.It provides reference for preventing unusual resonance of welding torch.

Abstract:In order to effectively mitigate the impact of hydraulic cylinder braking and effectively reduce the energy loss, a hydraulic accumulator was used to build a gravitational potential energy recovery system. The dynamic braking process and energy recovery were analyzed by using AMESim simulation platform.The results show that: in the first 0.5 s, hydraulic cylinder is in uniform motion, subsequently the system enters the braking process and begins to recover energy;starting from 1.4 s, the system is leaking, and the accumulator cannot continue to recover energy, so the brake circuit needs to be cut off by the cutoff valve;when the cutting valve initially produces the braking effect, the return oil flow is already in a very low state, so the buffer chamber will not be greatly impacted;under different accumulator volumes, the braking state of the system does not change, and the energy recovery is basically the same;after increasing the initial pressure of the accumulator, the braking process can be completed in less time and the energy recovered is lower.

Abstract:Vehicle suspension is one of the most important parts of the whole vehicle system. Its main function is to transfer force and moment from ground to the body, and to reduce impact load from road excitation on the frame, thus restraining the irregular movement of the wheel. As the semiactive suspension of vehicles has a simple structure, no external energy input, and can achieve similar functions with the active suspension, it has broad prospects for development. Therefore, the research on semiactive suspension system of vehicles is growing day by day. One of the research focuses is the semiactive control method. The control methods for MR vehicle suspension were focused on, including the modern control methods and intelligent control methods. The research about the semiactive control of vehicle suspension from the research group was introduced. Relevant analysis and conclusions can provide some theoretical reference and guidance for further research of vehicle semiactive suspension.

Abstract:In the process of longterm use, the performance of rolling bearings will degrade to different degrees. If the degradation degree of rolling bearings in work can be quantitatively evaluated, accidents can be avoided.The autoregressive (AR) model was used to filter the vibration signal of the rolling bearing in its whole life cycle.The ratio of residual component energy and signal energy after filtering were calculated,namely AR energy ratio, which was used as a feature vector.The feature vectors were processed by using the standardized min-max normalization method, then they were input to the fuzzy Cmeans (FCM) model. The performance degradation index was obtained and the performance degradation curve was depicted.The envelope spectrum analysis of the signal was carried out, and the correctness of the evaluation results was verified.

Abstract:Fault feature information extraction of broken tooth is often contaminated out by strong production background noises.Aiming at the problem,Autogram method was applied to extract the feature information.In the method,maximum overlapping discrete wavelet packet transform was utilized to decompose a contaminated signal of broken tooth fault into several signals,and each signal was called “node”.In order to depict the feature information comprehensively,unbiased autocorrelation of squared envelope for each node was computed,then one node was selected as the data source to be analyzed.For the sake of effective feature information extraction,threshold processing was introduced,and spectrum analysis could be more comprehensive.The method is effective through comparing the simulation signal sand the test ones.

Abstract:Aiming at the problem that the lubrication wear life of solid lubricated angular contact ball bearings can not be accurately predicted, a more accurate calculation model of wear life based on dynamic load distribution method was proposed, and the dynamic load distribution under the action of inner and outer ring loads was considered. Through the established dynamic load calculation model between the inner and outer rings and the raceway, the moving contact characteristics of the angular contact bearing were more accurately characterized. At the same time, the dynamic load segment calculation method of the entire bearing component was combined with the wear calculation model to establish the bearing wear model under the dynamic load distribution of the overall contact area. It provides reference for the wear life mechanism analysis under the bearing operation.