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[Objective] Clearance between motion pairs is commonly observed in mechanisms due to manufacturing errors in components, assembly requirements, and wear of the mechanisms. When the mechanism operates at high speeds with large loads and small cross-sectional areas, components are susceptible to elastic deformation. This elastic deformation, combined with the clearance in motion pairs, significantly restricts the motion accuracy of the entire mechanism, leading to chaotic behavior and ultimately reducing its stability and reliability. Therefore, it is essential to investigate the influence of the coupling effect between the clearance of the motion pair and the flexible component on the motion state of the mechanism. [Methods] This paper proposes a chaos identification method for a rigid-flexible coupling experimental teaching platform with revolute clearance joints. First, a revolute clearance joint model was established based on the three-state model of "contact-separation-collision." In addition, a flexible beam element model was created using the absolute node coordinate method. Following this, a dynamic model of the rigid-flexible coupling six-link experimental platform with revolute clearance joints was established using the Lagrange multiplier method. Finally, both qualitative and quantitative identifications of chaotic phenomena in the six-link experimental platform were conducted using phase diagrams, Poincaré maps, and maximum Lyapunov exponents. The nonlinear characteristics of the rigid experimental platform with clearance and the rigid-flexible coupling experimental platform with clearance were compared and analyzed. Additionally, the effects of different clearance values, driving speeds, and friction coefficients on the nonlinear characteristics of the experimental teaching platform were studied. [Results] The results obtained using methods such as phase diagrams, Poincaré maps, and maximum Lyapunov exponents indicate that compared with the rigid experimental teaching platform mechanism with revolute clearance, the vibration frequency of the rigid-flexible coupling experimental teaching platform mechanism with revolute clearance is higher, leading to reduced stability and more pronounced chaotic phenomena. The chaotic behavior at the clearance of the revolute pair intensifies with an increase in clearance size and driving speed, whereas it weakens as the friction coefficient increases. [Conclusions] The coupling effect between the clearance of the motion pair and the flexibility of the component reduces the stability of the mechanism, leading to the emergence of chaos. The chaos identification method based on the experimental teaching of rigid-flexible coupling with revolute clearance proposed in this article can effectively distinguish the motion states of the mechanism. This method provides a systematic and comprehensive theoretical foundation for the study of nonlinear dynamics in high-precision, high-performance multilink mechanisms. This not only enhances students' ability to analyze and practice the nonlinear characteristics of mechanisms but also increases the diversity, intuitiveness, and engagement of the teaching process, ultimately improving the quality of education. [ABSTRACT FROM AUTHOR]

Several ten-stages-compressor of a high bypass ratio turbofan engine was used as the research object, the change law of tip clearance and its effects on aerodynamic performance and stable boundary of the compressor were investigated based on a high speed compressor component, core engine and complete engine test facility. The mechanism and the sensitive area of tip clearance effect on the overall performance and each stage performance of multistage compressors was revealed by detailed simulation results of transonic and subsonic stage performance. The results show that the clearance change law of compressors of different sizes is consistent, which is mainly related to centrifugal force and temperature filed. Flow-pressure ratio and flow-efficiency characteristics of the compressor at design rotational speed Indicate a feature of whole reduction while the clearance increases, and the clearance has more impact on the back subsonic stage. With the increase of the tip clearance, the efficiency of the front transonic stages of the compressor does not decrease for the small ratio of clearance to the big blade height, but the work capacity of the back subsonic stage decreases obviously, and the influence of the clearance mainly concentrates on the back subsonic stage, which makes the compressor efficiency and stall margin droop. [ABSTRACT FROM AUTHOR]

Copyright of Large Electric Machine & Hydraulic Turbine is the property of Large Electric Machine & Hydraulic Turbine Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Ordnance Equipment Engineering is the property of Chongqing University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Lubrication Engineering (0254-0150) is the property of Editorial Office of LUBRICATION ENGINEERING and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Guangdong Architecture Civil Engineering is the property of Guangdong Architecture Civil Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Signal Processing is the property of Journal of Signal Processing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To raise the efficiency of finite element calculation of load distribution in large three-row roller slewing bearing, an equivalent modeling method using the combination of shell element and nonlinear spring element was proposed on the basis of the structural features of the assembly. The spring element was used to replace the load and deformation behavior of roller, and the shell element was used to simulate the contact area between the roller and raceway contact. The computational scale of the nonlinear contacts was reduced with this modeling approach, and the load distribution of bearing can be obtained efficiently with lower computational scale. The effectiveness of the finite element calculation model was validated with the static loading experiment. The roller-raceway contact analysis was conducted on the basis of the maximum contact load from the finite element calculation analysis. The stress distribution between the roller and raceway contact under different clearances was studied. The results show that the stress in the edge area of the roller-raceway contact increases with the increase of clearance, thus leading to the decreases of fatigue life.

Aiming at the phenomenon of vibration and abnormal joint response in the operation of walking robot，the dynamics method is adopted to simulate the contact state of the clearance model of the moving pair，and the natural frequency of the walking robot with clearance is analyzed，avoiding the problem that the nonlinear factors are ignored in the simulation analysis of the computational modal analysis method. With the help of transient dynamics simulation，the displacement response of the walking robot with clearance is calculated，and then through the Fourier transform，the frequency response curve is obtained，the corresponding frequency of the curve peak is the natural frequency of the walking robot with clearance. The existence of joint clearance can reduce the natural frequencies of the walking robot，but the clearance does not affect the mode shapes. The first-order mode is the sway vibration of the platform and the support leg along the X-axis，the second-order mode is orthogonal to the first-order mode，and the third-order mode is the torsional vibration of the platform and the support leg along the Z-axis.

The crank-group driving mechanism is a kind of linkage truss mechanism with redundant constraints. Aiming at the mechanism characteristics，based on the dynamics model of ‘continuous contact model’，a virtual simulation model of the crank-group mechanism with six cranks is established，and the dynamics characteristics of mechanism with different clearance radius of rotating pair are studied by using simulation software Admas. The results show that，in a certain range of required accuracy，the clearance size of the rotating pair has little effect on the displacement and velocity of the driven component，but has obvious effect on the acceleration and contact force of the driven component. With the larger clearance radius of the rotating pair，the smaller the amplitude of the vibration of the acceleration and contact force of the driven component，the larger the oscillation frequency.

Clearance joint and connecting rod flexibility are main factors that affect the dynamics performance of mechanism，which determine the reliability of mechanism operation. Crank and connecting rod mechanism as the object，the Lagrange multiplier method is used to establish the dynamics model of coupling connecting rod joint clearance and connecting rod flexible action. On this basis，the influence of clearance size，connecting rod flexibility and their coupling on the mechanism dynamics output response is systematically studied. The results show that，within the same cycle，the collisions are mainly concentrated in the early stage of the campaign close to the two sides of the crank，the connecting rod clearance increases，the collision between articulated components intensify，the oscillation amplitude of impact force and the embedding depth of increase obviously，and the stability of the axis trajectory is reduced，and the appropriate component flexible processing can reduce collisions caused by clearance joint.

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In order to research the influence of the time-varying stiffness of rolling bearings on the precision of spindle rotation of machine tools， a time-varying stiffness model of rolling bearings are established by considering the radial clearance. And the average stiffness and stiffness amplitude change rate are proposed to characterize the time-varying characteristics of stiffness. Taking deep groove ball bearings as an example， the influences of different radial clearances， loads， and numbers of bearing rolling elements on the time-varying stiffness of rolling bearings are analyzed. The results show that the average stiffness of the bearing is negatively related to the radial clearance and positively related to the load and the number of rolling elements； the stiffness amplitude change rate generally increases with the increase of the radial clearance， and decreases with the increase of the load and the number of rolling elements. But when the number of equivalent bearing rolling elements is an integer， the time-varying characteristics of rolling bearing stiffness are the most significant. In order to reduce the time-varying characteristics of bearing stiffness， a reasonable clearance and number of rolling elements should be selected according to the working conditions such as load and speed.

In order to select the best contact force calculation method for the dynamics performance analysis of multibody systems involving joints with clearance， a dynamics model of a crank slider mechanism involving joints with clearance is established and a systematic comparative analysis is performed for calculation methods of contact force with the crank slider mechanism involving joints with clearance as the object. The influence of the calculation method of contact force on dynamics performance analysis of the crank slider mechanism under different clearances， crank speeds and recovery factors is studied. The analysis results show that when studying the influences of changes in radial clearance， driving load， and recovery coefficient on dynamics of multibody systems， both the Lankarani-Nikravesh contact force model and the ZhiYing-QiShao contact force model are relatively reliable， and the ZhiYing-QiShao contact force model is the least sensitive to the recovery coefficient.

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Copyright of Journal of East China University of Science & Technology is the property of Journal of East China University of Science & Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Acta Materiae Compositae Sinica is the property of Acta Materiea Compositae Sinica Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Tooth surface wear and bearing clearance are important factors affecting gear system dynamics, in order to reveal the influence of tooth wears and bearing clearance on the dynamics of gear system, a six-degree-of-freedom bending-torsion coupled model is established, which takes into account the tooth surface wear, bearing clearance, friction and backlash. The dynamic differential equations are solved by Runge-Kutta method and the dynamic response of the system is obtained. The results show that when the gear changes in unworn phase to mild wear phase, the amplitude of dynamic transfer error decreases and the vibration is weakened. With the increment of tooth surface wear, the amplitude of dynamic transmission error increases and the vibration is strengthened when the gear reaches severe wear phase. With the increase of bearing clearance, the peak-to-peak value of dynamic transfer error will increase and resonance phenomenon will appear, the stability of system will decrease.

For high-speed CAM with clearance in the process of running with reduced stability and increasing noise and wear and so on and on the basis of the characteristics of structure dynamics and kinematics, a kind of high speed CAM mechanism with clearance based on kinematics and dynamics multiple targets was put forward for optimization design. Optimization results show that we can find that the optimized CAM curves improve overall performance and part of the performance curves approach or exceed high-speed CAM common cycloid CAM curve when the three coefficients polynomial CAM curves and the standard CAM curve are compared. Among them, the weight seven variable coefficient polynomial CAM curve comprehensive performance is best and its noise is reduced accordingly. So it has higher engineering application value from these findings.

The gap can result in the characteristics of the main drive system of the mill become bad,the influence of the gap size on the system is the concern of enterprises. This paper is based on numerical simulation and finite element analysis,to study the main drive system of the initial mill with multiple gaps,its dynamic characteristics are changed due to the difference of gap size. a The difference of dynamic response and stress change of the system is obtained by using MATLAB numerical simulation and ANSYS finite element calculation. This two methods verify and supplement each other to provide theoretical reference for mill production practice.

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The load distribution considering clearance and deflection of the cross universal joint bearings of a JIEFANG truck is calculated by using MATLAB programming and ANSYS numerical analysis method. The load distribution calculation results are used as the input conditions for stress analysis. The contact stress analysis is carried out on the maximum loaded needle roller. Based on the obtained stress extremum,the life modified model of the cross universal joint bearings is established. The analysis results indicate that compared with traditional life calculation method,the modified bearing life calculation method takes into account the effect of clearance and deflection on the life of cross universal joint bearings. The prediction accuracy of the bearing life is significantly improved. The experimental verification results are in good agreement with the analysis conclusion.

Aiming at the problems of system stability, accuracy and reliability reduction caused by the clearance of the slider crank mechanism, the improved PSO algorithm is used to identify the slider crank mechanism with clearance, and the error generated by the clearance is applied with adaptive lubrication. The stick controller is compensated. Firstly, the traditional PSO algorithm is improved by adopting the non-linear decreasing method for the inertia factor and the weighted average method for the local optimal value; then, the traditional PSO algorithm and the improved PSO algorithm are used to analyze the crank slip with clearance. The block mechanism was identified; finally, an adaptive robust controller was designed to compensate for the error caused by the crank-slider mechanism gap. The research results show that compared with the traditional PSO algorithm, the application of the improved PSO algorithm has higher accuracy on the model established by the system identification; the signal tracking accuracy of the designed adaptive robust controller is improved by about 51% on average. [ABSTRACT FROM AUTHOR]

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Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Ordnance Industry Automation is the property of Editorial Board for Ordnance Industry Automation and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Engineering Mechanics / Gongcheng Lixue is the property of Engineering Mechanics Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The reliability of the reaction force developed in the lubricated revolute joint for a slider-crank system considering realistic joint characteristic,namely,joint with clearance and lubrication in the revolute pair,and the randomness of the system parameters is presented. The continuous approach and the hydrodynamic theory are used to evaluate the contact force for the case of joints modeled as a contact pair with dry contact and the force generated by lubrication action respectively. The system dynamic model was set up based on Newton-Euler method,The prediction accurary of Support Vector Machine Regression is difficult to reach the target accurary because the selection of parameters isn’t accurate. In order to overcome this limitation,the parameters are pretreated through Genetic Algorithm to get the optimum parameters values. Then approximate function relation between random parameters and performance function is derived and the reliability of the reaction force developed in the lubricated revolute joint of the crank-slider mechanism is discussed by Monte-Carlo method. Finally,take an example to verify the feasibility and effectiveness of the proposed method.

In order to solve the problem of the clearance on the slider-crank mechanism and improve the position precision of the slider-crank mechanism. Starting from the simple mechanism of slider-crank mechanism,the simplified model is established. By using the sensor to measure the movement parameters of artifacts of the slider-crank mechanism,then system parameters of the slider-crank mechanism are identified by using the method of parameter identification. Finally,the model of the slider-crank mechanism with clearance is established and the simulation analysis is carried out. The comparison results show that the model of using the method of parameter identification has high accuracy and modeling process is simple,a new train of thought for complex nonlinear modeling of the electromechanical system is provided.

Using appropriate series geneva mechanism can eliminate the flexible impact in theoretically,but the unavoidable clearances between pin and slot exist in practical engineering application. In order to research the effects of the independent two- stage clearances on eliminating the flexible impact of the whole mechanism,a simulation model of series geneva mechanism containing the clearances is built by using ADAMS software firstly,and the influence mechanism of the clearances affect eliminating the flexible impact of output wheel is conducted. Then the experiment group aiming at finding the influences of different clearances of two stages geneva mechanism on the last geneva wheel is set up. The results illustrate that when the clearances exists,although the output geneva mechanism can eliminate the flexible impact,the impact brought by the clearances has greater influence on it. The peak angular acceleration of the last stage geneva wheel is affected by the first stage pin- slot clearance more greatly than the second one. Finally,a guidance of using series geneva mechanism in actual is brought up: the minimum clearance that ensures the geneva mechanism in normal working condition of the first stage geneva mechanism should be guaranteed with a certain machining accuracy firstly.

Copyright of Journal of Ballistics / Dandao Xuebao is the property of Journal of Ballistics Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Acta Materiae Compositae Sinica is the property of Acta Materiea Compositae Sinica Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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Depending on the form of mechanism,the hinge wear and rod end bearing wear are considered respectively,and the self-lubricating rod end bearing wear model are established.Then the over-center locking reliability analysis model of four bar linkage mechanism is built under the "effective lever length theory"and "continuous contact model"hypothesis,besides,a reliability analysis method of over-center locking considering the initial clearance and wear is presented.The results show that the failure probability of mechanism over-center locking will rapidly increase after a certain number of cycles; the reliability of mechanism over-center locking will be significantly improved by using self-lubricating rod end spherical plain bearing.

Copyright of Journal of Engineering for Thermal Energy & Power / Reneng Dongli Gongcheng is the property of Journal of Engineering for Thermal Energy & Power and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The crank- group driving mechanism is a kind of under- actuated mechanism with redundant characteristics,aiming at the characteristics of mechanism,selecting continuous contact model for the joint clearance,the dynamics model of the basic structural unit- double crank mechanism with clearance is set up by the second kind Lagrange equation. Then,assume that the inertia force direction of no quality rod pointing to truss connecting rod,the derivation from the unit to the whole is carried out,and the dynamics model of the crank- group driving mechanism with clearance is established.

Tobacco leaf protein was extracted by alkali-solution and acid-isolation method from upper leaves in the field. The tobacco protein was hydrolyzed using trypsin, papain or protamex, respectively. The effect of different enzymolysis conditions on leaf protein hydrolysis degree and the DPPH clearance rate of tobacco leaf protein polypeptide were investigated. The results showed that the optimal enzymolysis conditions of protein peptide were different with those of the highest DPPH clearance rate of protein polypeptide. Using papain as an example, the optimal hydrolysis conditions for tobacco protein hydrolysis degree were enzymolysis temperature 50 °C, hydrolysis time 0.5 h, enzyme amount 3%, pH = 8. The optimal hydrolysis conditions for DPPH clearance rate were temperature 40 °C, enzymolysis time 2 h, enzyme amount 3 %, pH = 7. This indicated that the degree of hydrolysis of protein polypeptide was not positively correlated with its antioxidant activity. Protein peptide can be used as substrate for Maillard reaction or antioxidant, and it may be chosen corresponding optimal enzymatic conditions for different purposes. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Drainage & Irrigation Machinery Engineering / Paiguan Jixie Gongcheng Xuebao is the property of Editorial Department of Drainage & Irrigation Machinery Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)