最新刊期
期 1 ， 2018
- 摘要：Based on the KISSsoft software,the modification parameters of double helical gear are designed and researched. The performance indexes such as the transmission error,the normal force and the tooth surface load distribution are used to evaluate the modification parameters and the relation between performance indexes and design parameters of gear is given. Considering the effect of axis parallelism deviation and torque,the design of transverse profile modification and flank line modification of double helical gear is researched and then the design flow of modification parameters of double helical gear based on KISSsoft software is given. Taking one pair of double helical gear in an industry as an example,the original modification parameters are redesigned and optimized to solve large transmission error,load concentration of tooth surface and large normal force. Compared with the original modification parameters,the transmission error and the load concentration of tooth surface can be reduced and the normal force is decreased by the optimized modification parameters. The research show that,using KISSsoft software to optimize the modification parameters could avoid the traditional complicated optimization design flow by repeatedly rolling inspection and optimizing parameters.关键词：KISSsoft software;Double helical gear;Modification optimization design;Transmission error;Tooth surface load distribution
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发布时间：2022-10-20 - 摘要：The gear modification is an important technique to improve gear transmission performance. A new topological modification method with circular tooth profilein gear cutter and tooth drum-shaped is put forward. Based on the gear meshing theory and the tooth contact analysis（TCA） technology,the modification parameters for helical gear are designed,and error sensitivity is studied,that is,the effects of helix angle and pressure angle errors on the transmission error and contact trace. The study shows thats gear with the proposed topological modification is insensitive to the helix angle and pressure angle errors,and it has good performance without edge contact. The result provides a theoretical foundation for the modification of helical gear.关键词：Helical gear;Topological modification;Tooth contact analysis;Error sensitivity;Transmission error
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发布时间：2022-10-20 - 摘要：The elastohydrodynamic lubrication geometric model of centrifugal pollutants adhesion is established. The thermal elastohydrodynamic numerical simulation of water-lubricated hybrid journal bearings considering its lubricant pollution problem is carried out by using the Reynolds equation with thermal effect. The effect of centrifugal attachment on the surface texture of the bearing pad and the film thickness,pressure change of the lubricating film in the contact zone are studied. The influence of the film thickness and pressure of the contact zone are analyzed as the contaminants are centrifugally attached to plug the water inlet. The influence of the adhering layer on the temperature field of the contact zone is obtained. The results show that the centrifugal attachment of pollutants effectively improves the roughness of the surface of the bearing pad and alleviates the film thickness fluctuation in the contact area. The greater the degree of clogging of the pollutant to the water inlet,the smaller the water supply pressure,the smaller the minimum film thickness,the greater the maximum pressure,which is not conducive to bearing lubrication. The contaminant adhering layer has an effect on the temperature field of the contact zone of the water-lubricated hybrid journal bearing. When the difference of the physical parameters of the pollutant and the bearing material vary largely,the temperature field changes greatly.关键词：Pollutant;Centrifugal adhesion;Water-lubricated;Hybrid;Journal bearing
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发布时间：2022-10-20 - 摘要：Based on the transmission principle of planetary gear train,a method by using the signal flow graph is proposed to calculate the torque of complex planetary gear train. By combining the structure characteristics of transmission chain of planetary gear train with the transfer characteristic of signal flow,the signal flow graph models of compound system of XP type,PX type,T type,∏ type and E type of planetary gear train are established. The signal flow graph is used to simplify the calculation of topology model by using signal flow graph,the calculation formula of characteristic parameters for each component is obtained. The results show that this method has good visibility and high efficiency,a new method for the parameter calculation of complex planetary gear train is provided.关键词：Planetary gear train;Transmission characteristic;Signal flow graph;Torque
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发布时间：2022-10-20 - 摘要：The circular arc tooth trace（CATT） cylindrical gear is a new type of gear transmission,which can solve the problem existing in the traditional gears. The dynamic characteristics of the CATT gears are studied with different tool radius and modulus based on the finite element method to reveal its influence on its dynamic characteristics. The accurate 3D model of the CATT gear is established in the UG,and it is imported into the Workbench for the modal analysis of this new type of gear. The simulation results show that,in the case of other parameters are the same,the natural frequency of each order is gradually reducing,the influence of the tool radius on its dynamic characteristics is not significant.关键词：CATT;Modal analysis;Tool radius;Modulus;Finite element method
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发布时间：2022-10-20 - 摘要：Based on the transmission principle of the positive-drive cam mechanism,the tooth profile theory of a new type of liner-movable-gear-drive-mechanism with arbitrary tooth difference is proposed.The tooth profile equation of the shock wave and the center wheel is proposed,and the geometrical proof of the indirect conjugation of the tooth profile and the center tooth profile is carried out. The relationship among the number of movable teeth,the number of teeth of the shock wave and the number of teeth of the center wheel is deduced,and the feature that movable teeth should distribute uniformly is proved. The transmission ratio of the new movable gear extension is deduced in term of the relative angular velocity method. The design examples are provided to show the adoptability of the two kinds of tooth profile given,symmetrical tooth profile and asymmetric tooth profile.关键词：Positive-drive cam mechanism;Transmission ratio;Any tooth-difference;Tooth profile equation;Asymmetric tooth
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发布时间：2022-10-20 - 摘要：Aiming at the problem of modeling difficult of complex meshing surfaces of globoidal cam planetary mechanism,a method of 3D modeling by using simulated motion method is proposed in order to facilitate the modeling of the mechanism. The kinematics analysis of the mechanism must be carried out in this method and the motion simulation of analog components is carried out according to the motion relationship. The trajectory obtained by using simulation is scanned on the modeled component. Finally,the 3D model of the component is obtained. It is proved that the model is global free of interference and the motion form is simulated correctly.The method is efficient and accurate,the trajectory curve obtained by the simulation method can directly reflect the meshing law of the components.关键词：Globoidal cam planetary mechanism;Simulated motion;3D Modeling
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发布时间：2022-10-20 - 摘要：View of the shortcomings of the traditional lubrication system design,a design method based on Flowmaster software is put forward. Taking a certain type of wind turbine gearbox as an example,the power loss and the amount of oil supply are calculated,the lubrication system is simulated and the design is optimized.The experimental test of the lubrication system is carried out,which proved the validity of the lubrication system. The results show that,by using the Flowmaster software to design the wind turbine gearbox,the accurate control of flow and pressure can be achieved. When design the system,it must be noted that the temperature variety has a big effect to the gearbox oil pressure.
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发布时间：2022-10-20 - 摘要：Aiming at the problem of the low efficiency of NGWN-type planetary gear transmission with high speed ratio,the low-loss gear design that is optimizing modification coefficients and addendum coefficients simultaneously,reducing the contact ratio to reduce the mesh power loss can be applied to improve the gear transmission efficiency obviously. However,the change of contact ratio has an effect on dynamics of gear transmission. The NGWN（Ⅱ） type planetary gear transmission is taken as the research object,firstly,the relation between the contact ratio and system efficiency is obtained. Then,the dynamics model of NGWN（Ⅱ） type planetary gear transmission is built,the relation between contact ratio and dynamics performance of low-loss gear design is obtained. In the end,the select range of the contact ratio by using low-loss gear design is given,a theoretical guidance for the design of high-ratio planetary gear transmission with high efficiency and good dynamics performance is provided.关键词：High-ratio planetary gear transmission;Low-loss gear;Contact ratio;Efficiency;Dynamics
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发布时间：2022-10-20 - 摘要：Aiming at the low efficiency and low carrying capacity of NGWN（Ⅱ） planetary transmission,a design method which improve the efficiency and carrying capacity of the system by using low-loss and asymmetric gears is given. The efficiency influenced by contact ratios and the strength influenced by pressure angles and profile-shift coefficient are studied. On this basis,an optimization model aimed at highest efficiency and power density is described,which is subject to the conditions such as teeth,interference and strength. The research results show that the design method and the optimized design parameters can improve the transmission efficiency and carrying capacity of the system effectively.关键词：Low-loss and asymmetric gear;NGWN（Ⅱ）;Transmission efficiency;Gear strength
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发布时间：2022-10-20 - 摘要：In view of the situation that the workspace of the parallel robot is small,the workspace of an equivalent 8-SPU parallel mechanism is solved and optimized by using the three-dimensional boundary search method. Considering the rod length constraint,angle constraint,link interference,the inverse kinematics equation is established,all points in the workspace is searched,the three-dimensional boundary diagram with fixed posture is given,and then the influential curve of two mechanism parameters on workspace is given. Finally,the ratio of the volume with stroke of the rod is taken as the objective function,and particle swarm optimization algorithm is used to get the maximum function value. The global optimal solution is obtained,and the optimized three-dimensional diagram and the comprehensive indices comparison between unoptimized and optimized is given. The results show that the volume of workspace increases 143. 91% with 27. 59% raise of the stroke and the optimization effect is obvious.关键词：Redundant mechanism;Workspace;Parameter optimization
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发布时间：2022-10-20 - 摘要：In order to improve the meshing performance of cycloid bevel gear made by precision forging,the modification method of gear based on the deviation surface is proposed. Taking the pinion tooth surface of the cycloid bevel gear as the generating surface,the conjugating gear tooth surface equation satisfied the pre-determined transmission relationship is obtained according to the meshing principle. Based on the predesigned deviation surface with certain contact characteristics,the target tooth surfaces of gear can be obtained by superposing the deviation surfaces over the conjugate gear tooth ones. The finite element contact analysis is applied to the modification design for contact path in different directions. The simulation results show that bias correction is better than the others considering the flank contact stress,root tensile stress and contact pattern. The proposed modification method provides design reference for precision forging of the cycloid bevel gear.关键词：Cycloid bevel gear;Precision forging;Tooth flank modification;Deviation surface;Tooth flank contact
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发布时间：2022-10-20 - 摘要：The calculation of the meshing stiffness of the worm gear is the basis of the foundation of dynamics analysis. In view of the Uzbekistan Maidanak observatory 1 m telescope worm gear and worm drive renovation project,based on the theory of finite element analysis for ZC3 worm gear with loaded contact,a method for calculating the time-varying meshing stiffness of ZC3 worm gear is proposed. The finite element model is built by using Workbench and the meshing stiffness curve is obtained. The results show that the meshing curve of ZC3 worm has obvious periodicity. The minimum value of the meshing stiffness is 104. 4 MN·m,which appears at the position where the front pair of teeth exits meshing in the double tooth contact area of the teeth.And the maximum value of the meshing stiffness is 219. 7 MN·m,which appears in the middle of the single tooth contact zone. The basic conditions for the dynamics analysis of reconstruction project is provided by the research result.关键词：ZC3 worm gear;Loading contact analysis;Mesh stiffness;Finite element method
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发布时间：2022-10-20 - 摘要：The keys of design of high-ratio hypoid gears are determinations of gear and pinion pitch cone and calculations of geometric parameters. The research of the design of Gleason high-ratio hypoid gears with parallel tooth depth is carried out. The geometric constraints of spiral angle,pinion offset,face width and addendum factors are given out. The calculation method of geometric parameters are established. A pair of high-ratio hypoid gear which has the gear ratio of 1: 120 is designed. Through the actual machining,the correctness of the design method of high-ratio hypoid gears with parallel tooth depth is verified.关键词：Hypoid gear;High-ratio;Parallel tooth depth;Geometric constraint
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发布时间：2022-10-20 - 摘要：In order to reduce the volume shrinkage of polyamide 66（PA 66） gear injection molding as an example,by using the orthogonal test and Moldflow simulation software to obtain data as training samples of neural network,the neural network prediction model of the volume shrinkage of the gear is established,and the accuracy of the artificial neural network model is tested by the sample. Therefore,the time of optimizing process parameters is shortened,and the process parameters are optimized. The results show that,the efficiency of process design can be greatly improved by using the optimization of molding process parameters of plastic gear with combining the orthogonal test,numerical simulation and artificial neural network,and the accuracy is high.关键词：PA66 gear;Orthogonal test method;Artificial neural network;Molding process;Optimization
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发布时间：2022-10-20 - 摘要：The time-varying cutting force in the process of gear hobbing will cause chatter and affect the quality and the precision of workpiece. To analyze the vibration characteristics of hob and workpiece system,according to the theory of metal cutting,a calculation method of the time-varying cutting force is proposed,by considering single tooth cutter and double-tooth cutter. At the same time,a dynamics model of gear hobbing vibration with four degrees-of-freedom is established,the effects of different rotational speed on the vibration characteristics are obtained. Also,a vibration experiment of gear hobbing is carried out,and the dynamics model is proved to be correct based on contrastively analyzing the experimental data and the results of theoretical calculation. The results of study show that the new calculation method can calculate the vibration characteristics of the hob and workpiece accurately,which can provide a basis for studying the mechanism of cutting chatter and monitoring the conditions of machining system.关键词：Time-varying cutting force;Gear hobbing;Double-tooth cutter;Dynamics model
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发布时间：2022-10-20 - 摘要：The adaptive and sparsest time-frequency analysis（ASTFA） can realize signal spare decomposition adaptively by using Gauss-Newton iteration,but Gauss-Newton iteration is very sensitive to initial value which is determined by experience. In order to keep Gauss-Newton iteration converge,an improved method based on Firefly Algorithm（FA） is introduced to ASTFA,the validity of improvement is proved by simulation and experiment. Compared to traditional time-domain features,the minimum convex hull is capable to extract spatial information of the signal. One the basis,the forecasting model of gear crack fault based on FA-ASTFA and minimum convex hull is presented. The experimental analysis shows that the proposed model is more reliable and accurate than the traditional forecasting model for predicting the degree of gear incipient crack fault.关键词：Adaptive and sparsest time-frequency analysis;Firefly algorithm;Minimum convex hull;Gear crack forecasting model
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发布时间：2022-10-20 - 摘要：The fault signal and information of rolling bearing is often drowned in the noise,the traditional extraction of bearing fault feature methods are difficult to effectively extract the bearing fault feature. The SNR of blind source separation,combing the inherent time scale decomposition（ITD） and independent component analysis（ICA） method is used to reduce noise. The fault signal is decomposed by ITD. The PRC component will be decomposed by correlation coefficient criterion restructuring as the virtual noise channel. The KICA is used to realize the separation of fault signal and noise signal,then analysis on the effective fault signal envelope is carried out. The simulation and comparison of experiments of rolling bearing fault analysis indicates that this method is effective to extract the bearing fault feature.关键词：Rolling bearing;Inherent time scale decomposition（ITD）;Kernel independent component analysis（KICA）;Feature extraction
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发布时间：2022-10-20 - 摘要：The tooth profile deviation of cycloidal gears is related to its transmission stability and motion accuracy. Based on image measurement technology,a non-contact detection method for tooth profile deviation detection of cycloidal gear is proposed,in order to solve the problem of low detection efficiency and lack of sample detection in the process of cycloidal gear detection. Based on the optical image measurement system and the Sobel edge detection algorithm,the complete tooth profile image and the actual tooth profile edge point coordinate of the cycloid gear are obtained. Based on the tooth profile equation of cycloid gear and the method of partition approximation,the theoretical coordinate value of the normal direction along the measuring point are obtained,and the tooth profile deviation solving model is established,and the measurement of the tooth profile deviation of the cycloid gear is realized,the factors causing the tooth profile deviation of the cycloid gears are analyzed,the basis for the design and manufacture of the cycloid gears is provided.关键词：Cycloidal gear;Projection method;Tooth profile deviation;Precision detection
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发布时间：2022-10-20 - 摘要：There is a big space to improve measurement accuracy. Based on the oriented form grinding involute gear online measurement problem,combining with the characteristics of tooth profile measurement,the tooth profile measuring method and the model of error calculation are introduced. The improved least squares residuals of time series analysis method is selected to evaluate the measurement error. The experimental result shows that the residuals of time series analysis method is lower,the fitting curve is closer to the actual value and the method has higher precision of evaluation.关键词：Online measurement;Tooth form error;Time series analysis method
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发布时间：2022-10-20 - 摘要：The empirical mode decomposition（EMD） often suffers from the problem of mode mixing.Although the mode mixing can be alleviated to some degree by the ensemble EMD（EEMD）,but the introduction of assistant white noise in EEMD hinders time varying filtering performance of EMD. To enhance results of gearbox fault diagnosis,the time varying filter for EMD（TVFEMD） is introduced to examine gearbox vibration signals and a method for fault diagnosis of gearboxes based on TVFEMD is proposed. This proposed method is used to analyze the gearbox vibration data containing eccentricity of output shafts,the results show that the fault of eccentricity of output shafts of the gearbox can be effectively diagnosed,and a comparison between EMD,EEMD and TVFEMD indicates that the proposed method performs better in fault diagnosis of gearboxes.关键词：Signal analysis;Time varying filter for empirical mode decomposition;Gearbox;Fault diagnosis
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发布时间：2022-10-20 - 摘要：The Ensemble Empirical Mode Decomposition（EEMD） often encounters two difficulies in removing the added white noise residing in extracted components and easy production of spurious modes. Aiming at the deficiencies in the EEMD,the Complete Ensemble Empirical Mode Decomposition with Adaptive Noise（CEEMDAN） is introduced to examine gearbox fault data and a method for condition identification of gearboxes based on CEEMDAN energy entropy is proposed. In the proposed method,the gearbox vibration signal is decomposed by using the CEEMDAN,then the energy entropy of the decomposition results is calculated and the energy entropy is taken as a characteristic parameter to identify different gear operating condition. Afterwards,the proposed method is used to discriminate between normal,slight-scratch and medium-scratch gear operating conditions,and compared with the method based on EMD \ EEMD energy entropy. The results show that the proposed method can effectively discriminate between these three similar gear operating conditions,and the proposed method has a clear advantage in condition identification of gearboxes.关键词：CEEMDAN;Signal processing;Gear;Condition identification
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发布时间：2022-10-20 - 摘要：In order to obtain the better torsional vibration characteristics of the traction unit of the shearer,taking a new type of shearer traction drive system as the research object,based on its simplified kinetics model,by using the ADAMS software,the dynamics model is built,applies the step load and simulates the dynamic characteristics,and the potential energy curve of each elastic torsion spring is got. The torsional stiffness of the three torsion springs with the greatest potential are optimized and the optimized data are validated by using the above model,the result show that the potential energy distribution of the torsion spring is more uniform and the maximum potential energy value of each torsion spring has obviously decreased compared with the previous optimization. This method is of great significance to improve the torsional vibration characteristics of the traction unit of the shearer.关键词：Shearer;Traction unit;Torsional vibration characteristic;Dynamic optimization
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发布时间：2022-10-20 - 摘要：Aiming at the abnormal sound issue of the non-load SUV rear axle when driving in 90 100 km/h speed,by using the noise transfer function,the theoretical analysis is carried out,combining with NVH and vibration noise hammer test,the noise and vibration identification is carried out. Then,by using finite element method,the vibration response of the vehicle under different frequencies is analyzed,the fourth the frame supports is the key point while transfer vibration is identified,the cavity modes and noise amplification is caused.The experimental results are consistent with the results of finite element simulation. A solution is implemented to optimize the fourth frame support and restrain the transformation of the vibration noise. The test result shows the effect of interior noise reduction is significant,a reference for later project development is provided.关键词：SUV;Drive axle;Abnormal sound;Optimization
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发布时间：2022-10-20 - 摘要：The calculation of meshing force between chain links and sprocket is one of the chain transmission dynamics research focus. An approximate equation of sprocket meshing force is derived,under the condition of the local deformation before and after a single roller engaged with the tooth. Taking the main chain drive of a certain round balers as the research object,the dynamic characteristics and meshing force of main chain transmission system with multi-driven wheels in baling process of round balers under the condition of actual load torque are obtained through the simulation,the dynamics characterization of the chain drive system is analyzed and the validity of the model is verified,which present a certain operational method for actual agricultural machinery design.关键词：Round baler;Chain transmission with multi-wheel;Dynamics model;Polygon effect;Meshing impact
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发布时间：2022-10-20 - 摘要：The dynamics model of rolling bearing of automotive engine bearing-rotor system is established and the nonlinear dynamics differential equation is derived. The numerical solution is obtained by MATLAB after nondimensionalization,the change rule of dynamic response of rolling bearing is obtained. The influence of variations in each parameter on the dynamics performance of rolling bearing is thoroughly considered based on the response surface method. With the displacement amplitude response at a moment of the steady state as the research object,the influence sensitivity of each parameter on the performance of the bearing system is given quantitatively. The response pattern of the bearing system is grasped,and the sensitivity of each parameter on the bearing system is clarified,the theoretical guidance for subsequent optimization analysis on the performance parameters of the bearing system is provided.关键词：Nonlinear dynamics;Bearing rotor transmission;Response surface method;Sensitivity
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发布时间：2022-10-20 - 摘要：Comparing with traditional pulley transmissions,a new configuration of indirect Continuously Variable Transmissions（CVT） is proposed to enhance the driving torque and reduce the complexity of control logic. The proposed indirect CVT is designed to provide continuous variations in the transmission ratio and switch the output speed direction without reverse-gear device. In order to verify the performance of the proposed indirect CVT,Solidworks software is employed to build the complete 3D geometric model. Moreover,the transfer characteristics of indirect CVT are analyzed by using Simscape/Driveline Toolbox and the designed transmission test-bed. The simulation and experimental results prove that,the kinetics and dynamics performance of the proposed indirect CVT are consistent with theoretical analysis.关键词：CVT;Design development;3D-modelling;Simulation analysis;Experiment verification
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发布时间：2022-10-20 - 摘要：In order to improve the accuracy and stability of rolling bearing performance prediction,a prediction method combining soft predictive ART-RBF integrated forecasting model and confidence CV value is proposed. The soft ART is introduced into the RBF neural network to establish the soft ART-RBF neural network prediction model. Combining with weighted average technology,the establishment of integrated soft ART-RBF neural network prediction model is carried out. And the confidence degree（CV） value with rich fault information is obtained through the self-organizing map（SOM） network as a comprehensive index to characterize the degradation of rolling bearing performance. Finally,the above method is verified by the acceleration signal obtained by the accelerated fatigue test of the rolling bearing. The results show that the method can effectively improve the accuracy and stability of the prediction of the degradation trend of rolling bearings.关键词：Soft ART-RBF;Self-organizing mapping network;Confidence value;Rolling bearing;Prediction
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发布时间：2022-10-20 - 摘要：In order to diagnosis gear fault efficiently by using vibration signal,a new method of gear fault based on local mean decomposition（LMD）,fuzzy entropy and Isomap extraction is proposed,this method combines LMD,fuzzy entropy and Isomap. Firstly,by using the local mean decomposition（LMD） to decomposed the original vibration signal to obtain the components in different scales,and increases the adaptive matching waveform to alleviate the influence of end effects on decomposition results in the original LMD method. Then,considering fuzzy entropy can be use to distinguish the complexity of the signal effectively,so the fuzzy entropy of Product functions（PF） by LMD is calculated,a high-dimensional feature vector can be obtain with product functions. Finally,by using manifold learning（ISOMAP） on the high dimensional feature into low dimensional features which have better discrimination to describe different gear fault. It is applied to the gear experiment,the experimental results show that the method can effectively diagnose the gear faults and has certain superiority.关键词：Gear fault;Local mean decomposition;Fuzzy entropy;Manifold learning;ISOMAP
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发布时间：2022-10-20 -
Early Fault Diagnosis of Gear Box based on Variational Mode Decomposition and Fast Spectral Kurtosis
摘要：Aiming at the gear fault early sign signal is weak and the noise influence is serious,it is difficult to extract the fault characteristic frequency and band-pass filter parameters are not easy to determine the problem,a fault diagnosis method is proposed based on the variational modal decomposition（VMD） and fast spectral kurtosis（FSK）. Firstly,the vibration signal of the bearing fault is decomposed by VMD to get a series of band-limited intrinsic mode functions（BLIMFS）. Then,according to the correlation coefficient criterion,the spectral kurtosis is calculated for the components with large correlation coefficient,and the best center frequency and bandwidth are determined by spectral kurtosis graph. Finally,the filtered signal is analyzed by the energy operator envelope demodulation. The fault characteristic frequency can be extracted accurately from the envelope spectrum. Through the analysis of simulation signal and experimental data of gear fault,the results show that the method can effectively reduce the influence of the noise and accurately realize the extraction of weak gear fault feature information.关键词：VMD;Fast spectral kurtosis;Gear;Early fault;Envelope demodulation- 3
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发布时间：2022-10-20 - 摘要：The screw theory is adopted to analyze the constraint of planar mechanisms branch link on mobile platform,the redundant constraint and partial degree of freedom of mechanism is found out,and the formula of degree of freedom is modified,the mobility of planar mechanisms is researched by analyzing constraints virtual power of mechanisms branch link,which can judge whether mechanism move continuously. The effectiveness of proposed method is verified by an example of a planar instantaneous motion mechanism. Finally,taking a radar vehicle-borne array lifting mechanism as research object,the results show that the analysis method of the degree of freedom and mobility is suitable for complex planar mechanisms which contain redundant constraint.关键词：Screw theory;Constraint;Degree of freedom;Mobility
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发布时间：2022-10-20 - 摘要：The deflector by controlling the warhead relative to the missile deflection of a certain angle to change the aerodynamic characteristics and trajectory characteristics of the projectile to achieve the control of the shooting point. Based on this background,a flexible hinge amplifier is designed to amplify the output displacement of the Giant Magnetostrictive Actuator（GMA）. First of all,the maximum output displacement of the amplification mechanism is deduced and calculated. Then,under the given displacement,it is calculated that there is a linear relationship between the input force and the output displacement. The existence of the linear relation is verified by the simulation of the finite element software,compared with the calculated results,it is concluded that the existence of internal reaction force causes additional displacement loss. Finally,combined with the control principle of GMA output force,the relationship between output displacement and GMA output force and total magnetization is deduced.关键词：Deflected warhead;Flexible hinge;Displacement loss;Giant magnetostrictive actuator
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发布时间：2022-10-20 - 摘要：The packaging carton papers of products need to be checked by quality control machine after printing. Thus,a stack of carton papers shall be taken out one by one and placed onto conveyor belt. A paper picking mechanism composed of two cams and five links（including vacuum suction cups） is designed. By alternate use of inversion-graphic method and fitting of analytical formula,the profile of two cams is obtained.With a higher revolution speed,the proposed paper-picking mechanism can steadily pick 1200 carton papers every minute. Driven by the cam-linkage mechanism,its paper-picking suction cup can move in complex trajectories. Instead of interfering with paper bin,the suction cup is completely fitted to paper bin during paper picking and pauses at the right time to provide negative pressure in harmony with gas path. In this way,a smooth and reliable paper picking process is guaranteed.关键词：Paper picking mechanism;Cam link;Graphical method;Analytical method
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发布时间：2022-10-20 - 摘要：The support vector machine（SVM） can avoid the overlearning phenomenon in the case of small training samples,so that the generalization ability can be maximized. The problem that the SVM parameters cannot be selected adaptively is studied. By using the global search characteristic of the genetic algorithm,the parameters of the support vector machine are optimized and the optimal parameters of the support vector machine are obtained. This method is used to study the acoustic emission detection of gear fault,and the experimental system is composed of PCI-2 acoustic emission system and rotary machinery vibration fault simulation test bed. The accuracy of gear fault classification is 10% higher than that before optimization,which is very important for gear fault diagnosis.关键词：Acoustic emission;Support vector machine;Genetic algorithm;Optimization kernel function
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发布时间：2022-10-20 - 摘要：For unmanned helicopter economic cruises,main rotor speed changes could be significant. At present,the most effective method of changing the main rotor speed associated with the great speed range and low cost is a variable speed gear transmission employed in main gearbox. Thus,aiming at the speed difference of the helicopter main rotor during takeoff and cruise,the variable gear transmission is addressed and applied by western countries. According to the limited foreign literature,the configuration of two-stage variable speed gear transmission in unmanned helicopter are sketched,which would benefit to improve unmanned helicopter transmission system developments in China.关键词：Unmanned helicopter transmission system;Two-stage variable speed gear transmission;Transmission configuration scheme
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发布时间：2022-10-20 - 摘要：The significance and value of research on the key technologies of AMT is discussed,and the structural characteristics,performance and application of 3 types of AMT are analyzed. Besides,the research status and achievements of AMT in recent years from the aspects of the design & optimization of shift control system and the design of shift actuator are described. Furthermore,the prospects of the future and development trend of AMT’s research hotspots is carried out. A guiding value in the development of AMT technology is provided.关键词：Automated mechanical transmission;Research status;Development trend
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发布时间：2022-10-20
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