A new hybrid piezoelectric ultrasonic motor, which consists of one rotor and two stators, was proposed in this paper. In order to match the resonance frequencies of longitudinal vibration and torsional vibration excit...A new hybrid piezoelectric ultrasonic motor, which consists of one rotor and two stators, was proposed in this paper. In order to match the resonance frequencies of longitudinal vibration and torsional vibration excited in the stators, a symmetrical structure was adopted in design of the motor. A so-called mass matching method, namely adding two rings to the outside circumference of the two stators respectively, was used to adjust the resonance frequencies of these two vibrations. A finite element model was developed using ANSYS software for the purpose of analyzing the resonance frequencies of longitudinal vibration and torsional vibration as well as the function of the adjusting rings. The results show that the resonance frequency of torsional vibration varies with the position of the ring, but the resonance frequency of longitudinal vibration changes little. By means of adjusting the mass and the position of the rings, the first order resonance frequency of longitudinal vibration is coincided with that of torsional vibration and the value is 20.75kHz. An experimental prototype motor was fabricated according to the analytical results and its performance is in agreement with the theoretical predictions. The speed of motor reaches the maximum 92r/min at the working frequency 19.0kHz.展开更多
Fretting in the partial-slip and gross-slip regimes under a constant normal load is considered.The tangential force-displacement relations for the forward and backward motions are described based the generalized Catta...Fretting in the partial-slip and gross-slip regimes under a constant normal load is considered.The tangential force-displacement relations for the forward and backward motions are described based the generalized Cattaneo-Mindlin theory of tangential contact and Masing's hypothesis on modelling the force-displacement hysteretic loop.Besides the critical force and displacement parameters(characterizing the triggering of sliding),the model includes one dimensionless fitting parameter that tunes the tangential contact stiffness of the friction-contact interface.Explicit expressions are derived for the main tribological parameters of the fretting loop,including the slip index and the signal index.The presented phenomenological modelling approach has been applied to the analysis of two sets of experimental data taken from the literature.It has been shown that the experimentally observed simple relation of a rational type between the slip index and the slip ratio corresponds to the gross-slip asymptotics of the corresponding model-based predicted relation.The known quantitative criteria for the transition from the partial slip regime to the gross slip regime are expressed in terms of the stiffness parameter,and a novel geometric transition criterion is formulated.展开更多
A nonlinear analysis of the energy consistency of multivariable finite elements based onincompatible trial functions is presented. The nonlinear forms of the convergence and opti-mization condition are set up. The rel...A nonlinear analysis of the energy consistency of multivariable finite elements based onincompatible trial functions is presented. The nonlinear forms of the convergence and opti-mization condition are set up. The relevant optimization approach for hybrid elements andthe optimal parameter matching is suggested and applied to the 3-dimensional problem ofelasticity.展开更多
文摘A new hybrid piezoelectric ultrasonic motor, which consists of one rotor and two stators, was proposed in this paper. In order to match the resonance frequencies of longitudinal vibration and torsional vibration excited in the stators, a symmetrical structure was adopted in design of the motor. A so-called mass matching method, namely adding two rings to the outside circumference of the two stators respectively, was used to adjust the resonance frequencies of these two vibrations. A finite element model was developed using ANSYS software for the purpose of analyzing the resonance frequencies of longitudinal vibration and torsional vibration as well as the function of the adjusting rings. The results show that the resonance frequency of torsional vibration varies with the position of the ring, but the resonance frequency of longitudinal vibration changes little. By means of adjusting the mass and the position of the rings, the first order resonance frequency of longitudinal vibration is coincided with that of torsional vibration and the value is 20.75kHz. An experimental prototype motor was fabricated according to the analytical results and its performance is in agreement with the theoretical predictions. The speed of motor reaches the maximum 92r/min at the working frequency 19.0kHz.
基金supported by the 2021 Yeungnam University Research Grant.
文摘Fretting in the partial-slip and gross-slip regimes under a constant normal load is considered.The tangential force-displacement relations for the forward and backward motions are described based the generalized Cattaneo-Mindlin theory of tangential contact and Masing's hypothesis on modelling the force-displacement hysteretic loop.Besides the critical force and displacement parameters(characterizing the triggering of sliding),the model includes one dimensionless fitting parameter that tunes the tangential contact stiffness of the friction-contact interface.Explicit expressions are derived for the main tribological parameters of the fretting loop,including the slip index and the signal index.The presented phenomenological modelling approach has been applied to the analysis of two sets of experimental data taken from the literature.It has been shown that the experimentally observed simple relation of a rational type between the slip index and the slip ratio corresponds to the gross-slip asymptotics of the corresponding model-based predicted relation.The known quantitative criteria for the transition from the partial slip regime to the gross slip regime are expressed in terms of the stiffness parameter,and a novel geometric transition criterion is formulated.
基金The work was undertaken with the support of the Alexader von Humboldt Foundation.
文摘A nonlinear analysis of the energy consistency of multivariable finite elements based onincompatible trial functions is presented. The nonlinear forms of the convergence and opti-mization condition are set up. The relevant optimization approach for hybrid elements andthe optimal parameter matching is suggested and applied to the 3-dimensional problem ofelasticity.
