Recent zbMATH articles in MSC 70E55https://zbmath.org/atom/cc/70E552024-03-13T18:33:02.981707ZWerkzeugOn the relative rotation of rigid parts and the visco-elastic torsion bushing elementhttps://zbmath.org/1528.700022024-03-13T18:33:02.981707Z"Lidström, Per"https://zbmath.org/authors/?q=ai:lidstrom.perSummary: In this paper the interaction between two rigid parts of a multibody, connected by an ideal spherical joint equipped with a visco-elastic torsion bushing element, is derived. The model allows for arbitrary relative rotations of the parts and involves a non-linear torsion stiffness of the bushing. An expression for the interaction between the parts is derived and a specialization to the isotropic bushing element is presented.Dynamic modeling and analysis of hybrid driven multi-link press mechanism considering non-uniform wear clearance of revolute jointshttps://zbmath.org/1528.700082024-03-13T18:33:02.981707Z"Chen, Xiulong"https://zbmath.org/authors/?q=ai:chen.xiulong"Tang, Yuefei"https://zbmath.org/authors/?q=ai:tang.yuefei"Gao, Shun"https://zbmath.org/authors/?q=ai:gao.shunSummary: The multi-link press mechanism is developing in the direction of high speed and high precision. However, the non-uniform wear of joint clearance seriously affects the output motion accuracy of mechanism. In order to accurately predict the impact of wear clearance on precision press mechanism, this paper takes the hybrid drive seven-bar press mechanism as an example, a method of dynamic modeling and analysis for the press mechanism with non-uniform wear clearance is developed. First, the contact force and friction force at the clearance are solved based on the L-N model and modified Coulomb friction model respectively, and the dynamic model of press mechanism with clearances is developed by Lagrangian multiplier method. Then, the wear characteristics of joint clearance are predicted by Archard model. Finally, the influences of factors such as wear times, friction coefficient and driving velocities on wear characteristics of kinematic pair and the dynamic response of press mechanism are discussed respectively. This study offers a theoretical basis for dynamic behavior prediction of press mechanism with multiple non-uniform wear clearances, and lays a foundation for the design and manufacture of high-precision press.Dynamic characteristics of helical gears incorporating the effects of coupled sliding frictionhttps://zbmath.org/1528.700092024-03-13T18:33:02.981707Z"Jiang, Hanjun"https://zbmath.org/authors/?q=ai:jiang.hanjun"Liu, Fuhao"https://zbmath.org/authors/?q=ai:liu.fuhaoSummary: Sliding friction is an important source of excitation for gear vibration and noise. However, the axial friction caused by the axial mesh force of the helical gear may excite the gear vibration, which is often ignored by researchers. In this study, firstly, an analytical model of mesh stiffness for helical gears incorporating the friction force and mesh force is proposed. And then, a dynamic model of helical gears with coupled sliding friction is established. The dynamic model includes the transverse friction, the axial friction and the effect of friction on mesh stiffness. Finally, the effect of coupled sliding friction on the dynamic characteristics of helical gears incorporating the proposed analytical mesh stiffness model is investigated. The results show that friction leads to the increase or reduction of mesh stiffness before or after the mesh position where the direction of the friction force is reversed. The oscillations of the dynamic responses become more significant incorporating the effects of coupled sliding friction, especially with the increase of friction coefficient. The developed dynamic model of helical gears incorporating the effects of coupled sliding friction may lead to a more realistic dynamic response.Calculation method of mesh stiffness for helical gear pair with manufacturing errors, assembly errors and tooth modificationshttps://zbmath.org/1528.700102024-03-13T18:33:02.981707Z"Liu, Chang"https://zbmath.org/authors/?q=ai:liu.chang.1|liu.chuang|liu.chang"Shi, Wankai"https://zbmath.org/authors/?q=ai:shi.wankai"Liu, Kun"https://zbmath.org/authors/?q=ai:liu.kunSummary: For the accurate calculation of the time-varying mesh stiffness (TVMS) of helical gear pairs, a novel method is proposed in this paper. This proposed method can predict the TVMS based on the gear accuracy grade or the measurement coordinates of the tooth surface. The abnormal meshing phenomena caused by manufacturing errors (MEs), assembly errors (AEs), and tooth modifications (TMs), such as the loss of contact of tooth pairs, out-of-line meshing, and eccentric loads, are considered in the calculation process. The proposed method was verified to be effective for both spur and helical gear pairs. The effects of MEs, AEs, and TMs on the TVMS of helical gear pairs were also investigated. The results showed that the pitch, helix, and misalignment deviations were the main influencing factors of the TVMS in MEs and AEs. Both profile modification and lead crowning reduced the mean of the TVMS. The proposed method is expected to provide accurate TVMS excitation data of gear transmission systems for dynamic analysis.A dynamic model as a tool for design and optimization of propulsion systems of transport meanshttps://zbmath.org/1528.700112024-03-13T18:33:02.981707Z"Peruń, Grzegorz"https://zbmath.org/authors/?q=ai:perun.grzegorzSummary: Designing power transmission systems is a complex and often time-consuming problem. In this task, various computational tools make it possible to speed up the process and verify a great many different solutions before the final one is developed. It is widely possible today to conduct computer simulations of the operation of various devices before the first physical prototype is built. The article presents an example of a dynamic model of power transmission systems, which has been developed to support work aimed at designing new and optimizing existing systems of that type, as well as to help diagnose them by designing diagnostic algorithms sensitive to early stages of damage development. The paper also presents sample results of tests conducted with the model, used at the gear design stage. In the presented model, the main goal is to reproduce the phenomena occurring in gears as well as possible, using numerous experiments in this direction featured in the literature. Many already historical models present different ways of modeling, but they often made significant simplifications, required by the limitations of the nature of computational capabilities. Differences also result from the purpose of the models being developed, and the analysis of these different ways of doing things makes it possible to choose the most appropriate approach.Changing the spatial orientation of a rigid body using one moving mass in the presence of external forceshttps://zbmath.org/1528.700122024-03-13T18:33:02.981707Z"Shmatkov, Anton M."https://zbmath.org/authors/?q=ai:shmatkov.anton-mSummary: The problem of changing the spatial orientation of a rigid body according to a given program using a movable mass interacting with it in the presence of external forces is considered. An equation is obtained that describes the motion of this mass. The properties that the statement of the problem must satisfy in order for it to have a solution are revealed. Equations for calculating the reorientation program are obtained. They are based on the properties of the vector, which is the difference between the vector of the derivative of the angular momentum of a rigid body, determined by a given reorientation program, and the vector of the moment of external forces acting on the solid during the implementation of this program. It is shown that this difference determines three main variants of the algorithm. For the most complicated case, an example of the spatial reorientation of a mechanical system is considered. The resulting relationships can be used to control spacecraft and robotic systems.On the combination of multiple harmonics in direct and parametric forcing of an oscillator: new results on parametric amplificationhttps://zbmath.org/1528.700232024-03-13T18:33:02.981707Z"Abboud, Eddy"https://zbmath.org/authors/?q=ai:abboud.eddy"Grolet, Aurélien"https://zbmath.org/authors/?q=ai:grolet.aurelien"Mahe, Hervé"https://zbmath.org/authors/?q=ai:mahe.herve"Thomas, Olivier"https://zbmath.org/authors/?q=ai:thomas.olivierSummary: In this article, we focus on the study of a forced single degree of freedom Hill-type differential equation, which can be found in particular in the modeling of gear interactions. We consider that the variable part of the stiffness is composed of several harmonics, and that the forcing term contains a constant part and a single harmonic component. The response of the equation is estimated using methods such as the multiple scale method and the harmonic balance method, and the results are compared to the ones obtained using numerical time integration. The phenomenon of parametric amplification, classically observed when the second harmonic of the parametric driving interacts with the first harmonic of the direct driving, is here observed and quantitatively investigated in the case of more complex direct and parametric interactions. The simplest case is the one with a constant direct forcing, seldom described in the literature. Then, more complex situations with both harmonic and constant forcing leads to parametric amplification with more complex behavior.On the dynamics of vibro-impact systems with ideal and non-ideal excitationhttps://zbmath.org/1528.700302024-03-13T18:33:02.981707Z"Zukovic, Miodrag"https://zbmath.org/authors/?q=ai:zukovic.miodrag"Hajradinovic, Dzanko"https://zbmath.org/authors/?q=ai:hajradinovic.dzanko"Kovacic, Ivana"https://zbmath.org/authors/?q=ai:kovacic.ivanaSummary: This study is concerned with modelling and analyses of a vibro-impact system consisting of a crank-slider mechanism and one oscillator attached to it, where the system is exposed to a non-ideal excitation. The impact occurs during the motion of the oscillator when it fits a base, and the excitation of the driving source is affected by this behaviour. The aim is to determine the interaction between a driving torque and the motion of the oscillator. To achieve this aim in a methodologically sound manner, both vibrating and vibro-impact systems with an ideal and non-ideal excitation are analysed. Analytical and numerical solutions are obtained for the vibrating system with the ideal excitation. Numerical analyses of the vibrating system with the non-ideal excitation is then conducted, where the characteristic curves for this system are found analytically. Numerical simulations are also carried out for other two systems and the results obtained are shown in terms of frequency-response diagrams, time-displacement diagrams and basins of attraction. The results found for different systems are compared mutually, and the differences between them are pointed out. Impact solutions for different regions of the excitation frequency are shown. For the vibro-impact system with the non-ideal excitation, the average value of its frequency is used.Integration of variable stiffness actuators in a five-bar device to assist in active rehabilitation of the armhttps://zbmath.org/1528.740772024-03-13T18:33:02.981707Z"Contreras-Calderón, M. G."https://zbmath.org/authors/?q=ai:contreras-calderon.m-g"Castillo-Castañeda, E."https://zbmath.org/authors/?q=ai:castillo-castaneda.eduardo"Laribi, M. A."https://zbmath.org/authors/?q=ai:laribi.m-aSummary: Active arm rehabilitation involves restoring muscle tone by applying force to the arm to produce traction and compression on the muscles. Devices for rehabilitation assistance can be exoskeleton or end-effector type. This paper uses an end-effector type device, which provides an opposing force to the patient's arm's movement to tone their muscles during active rehabilitation. To provide that force, large and expensive motors with high torque are required. In order to avoid the use of motors, it is proposing a variable stiffness actuator integrated into a five-bar mechanism for active arm rehabilitation assistance in this work. The five-bar mechanism has a pantograph attached to amplify the workspace and emulates the arm rehabilitation trajectories, the patient holding onto the end-effector to trace the trajectories. The end-effector provides a constant opposing force to the patient's arm's movement, which activates the muscles. Thus, our proposal is the integration of an actuator with variable stiffness to replace the motors. The mechanism synthesis is presented to determine the parameters to vary the stiffness that provides a constant force in the five-bar mechanism end-effector.