The Experts below are selected from a list of 156 Experts worldwide ranked by ideXlab platform

Zhiyong Zhang - One of the best experts on this subject based on the ideXlab platform.

  • Experiments and Numerical Results for Varying Compliance Contact Resonance in a Rigid Rotor–Ball Bearing System
    Journal of Tribology-transactions of The Asme, 2017
    Co-Authors: Rui Yang, Yushu Chen, Zhiyong Zhang
    Abstract:

    This paper investigates the nonlinear Characteristics of varying compliance contact resonance in a rotor–bearing system and takes into consideration the Hertzian contact deformation and internal radial clearance. We created an experimental rig of a rigid rotor supported by rolling element bearings. In the course of the rotational speed run up and down, the frequency–amplitude curves of the varying compliance vibrations were observed during experiments using different radial loads and compared with the results of our numerical simulations. The experimental and numerical results indicate that the varying compliance contact resonance in the vertical direction presents the soft Spring Characteristic, while the soft and hard Spring Characteristics coexist for the horizontal resonance.

  • Experiments and numerical results for varying compliance vibrations in a rigid-rotor ball bearing system
    Journal of Tribology, 2017
    Co-Authors: Yulin Jin, Lei Hou, Yushu Chen, Rui Yang, Zhiyong Zhang
    Abstract:

    This paper investigates the nonlinear Characteristics of varying compliance contact resonance in a rotor–bearing system and takes into consideration the Hertzian contact deformation and internal radial clearance. We created an experimental rig of a rigid rotor supported by rolling element bearings. In the course of the rotational speed run up and down, the frequency–amplitude curves of the varying compliance vibrations were observed during experiments using different radial loads and compared with the results of our numerical simulations. The experimental and numerical results indicate that the varying compliance contact resonance in the vertical direction presents the soft Spring Characteristic, while the soft and hard Spring Characteristics coexist for the horizontal resonance.

Yulin Jin - One of the best experts on this subject based on the ideXlab platform.

  • Experiments and numerical results for varying compliance vibrations in a rigid-rotor ball bearing system
    Journal of Tribology, 2017
    Co-Authors: Yulin Jin, Lei Hou, Yushu Chen, Rui Yang, Zhiyong Zhang
    Abstract:

    This paper investigates the nonlinear Characteristics of varying compliance contact resonance in a rotor–bearing system and takes into consideration the Hertzian contact deformation and internal radial clearance. We created an experimental rig of a rigid rotor supported by rolling element bearings. In the course of the rotational speed run up and down, the frequency–amplitude curves of the varying compliance vibrations were observed during experiments using different radial loads and compared with the results of our numerical simulations. The experimental and numerical results indicate that the varying compliance contact resonance in the vertical direction presents the soft Spring Characteristic, while the soft and hard Spring Characteristics coexist for the horizontal resonance.

Rui Yang - One of the best experts on this subject based on the ideXlab platform.

  • Experiments and Numerical Results for Varying Compliance Contact Resonance in a Rigid Rotor–Ball Bearing System
    Journal of Tribology-transactions of The Asme, 2017
    Co-Authors: Rui Yang, Yushu Chen, Zhiyong Zhang
    Abstract:

    This paper investigates the nonlinear Characteristics of varying compliance contact resonance in a rotor–bearing system and takes into consideration the Hertzian contact deformation and internal radial clearance. We created an experimental rig of a rigid rotor supported by rolling element bearings. In the course of the rotational speed run up and down, the frequency–amplitude curves of the varying compliance vibrations were observed during experiments using different radial loads and compared with the results of our numerical simulations. The experimental and numerical results indicate that the varying compliance contact resonance in the vertical direction presents the soft Spring Characteristic, while the soft and hard Spring Characteristics coexist for the horizontal resonance.

  • Experiments and numerical results for varying compliance vibrations in a rigid-rotor ball bearing system
    Journal of Tribology, 2017
    Co-Authors: Yulin Jin, Lei Hou, Yushu Chen, Rui Yang, Zhiyong Zhang
    Abstract:

    This paper investigates the nonlinear Characteristics of varying compliance contact resonance in a rotor–bearing system and takes into consideration the Hertzian contact deformation and internal radial clearance. We created an experimental rig of a rigid rotor supported by rolling element bearings. In the course of the rotational speed run up and down, the frequency–amplitude curves of the varying compliance vibrations were observed during experiments using different radial loads and compared with the results of our numerical simulations. The experimental and numerical results indicate that the varying compliance contact resonance in the vertical direction presents the soft Spring Characteristic, while the soft and hard Spring Characteristics coexist for the horizontal resonance.

  • Dynamic Characteristics of flexible rotor with squeeze film damper excited by two frequencies
    Nonlinear Dynamics, 2016
    Co-Authors: Huizheng Chen, Yushu Chen, Rui Yang
    Abstract:

    This paper is focused on the dynamic Characteristics of a flexible rotor with squeeze film damper excited by two frequencies. The multiple harmonic balance method and Runge–Kutta method are combined to analyze the periodic solution and quasi-periodic solution of the system. The nonlinear Characteristics discussed are fastened on the resonance region corresponding, respectively, to the rigid body translation mode and first bending mode. In the former region, the motion of disk center shows the ‘hard Spring’ Characteristic, and the combination frequencies are dominated by the difference between double low excitation frequency and high excitation frequency and the difference between double high excitation frequency and low excitation frequency. In the latter region, however, the combination frequencies are dominated by the difference between high excitation frequency and double low excitation frequency and the difference between triple low excitation frequency and double high excitation frequency. Moreover, the motion of disk center shows a kind of ‘cross’, ‘soft Spring’ or ‘hard Spring’ Characteristics with the variation of the ratio of the two excitation frequencies. Besides, the independent quasi-periodic solution coexists with the periodic solution in these cases. The system is sensitive to the ratio of excitation frequencies, and it could have two independent quasi-periodic solutions in some conditions. The results in this paper provide a reveal of nonlinear Characteristics in this type of double excitation nonlinear rotor system.

Yushu Chen - One of the best experts on this subject based on the ideXlab platform.

  • Experiments and Numerical Results for Varying Compliance Contact Resonance in a Rigid Rotor–Ball Bearing System
    Journal of Tribology-transactions of The Asme, 2017
    Co-Authors: Rui Yang, Yushu Chen, Zhiyong Zhang
    Abstract:

    This paper investigates the nonlinear Characteristics of varying compliance contact resonance in a rotor–bearing system and takes into consideration the Hertzian contact deformation and internal radial clearance. We created an experimental rig of a rigid rotor supported by rolling element bearings. In the course of the rotational speed run up and down, the frequency–amplitude curves of the varying compliance vibrations were observed during experiments using different radial loads and compared with the results of our numerical simulations. The experimental and numerical results indicate that the varying compliance contact resonance in the vertical direction presents the soft Spring Characteristic, while the soft and hard Spring Characteristics coexist for the horizontal resonance.

  • Experiments and numerical results for varying compliance vibrations in a rigid-rotor ball bearing system
    Journal of Tribology, 2017
    Co-Authors: Yulin Jin, Lei Hou, Yushu Chen, Rui Yang, Zhiyong Zhang
    Abstract:

    This paper investigates the nonlinear Characteristics of varying compliance contact resonance in a rotor–bearing system and takes into consideration the Hertzian contact deformation and internal radial clearance. We created an experimental rig of a rigid rotor supported by rolling element bearings. In the course of the rotational speed run up and down, the frequency–amplitude curves of the varying compliance vibrations were observed during experiments using different radial loads and compared with the results of our numerical simulations. The experimental and numerical results indicate that the varying compliance contact resonance in the vertical direction presents the soft Spring Characteristic, while the soft and hard Spring Characteristics coexist for the horizontal resonance.

  • Dynamic Characteristics of flexible rotor with squeeze film damper excited by two frequencies
    Nonlinear Dynamics, 2016
    Co-Authors: Huizheng Chen, Yushu Chen, Rui Yang
    Abstract:

    This paper is focused on the dynamic Characteristics of a flexible rotor with squeeze film damper excited by two frequencies. The multiple harmonic balance method and Runge–Kutta method are combined to analyze the periodic solution and quasi-periodic solution of the system. The nonlinear Characteristics discussed are fastened on the resonance region corresponding, respectively, to the rigid body translation mode and first bending mode. In the former region, the motion of disk center shows the ‘hard Spring’ Characteristic, and the combination frequencies are dominated by the difference between double low excitation frequency and high excitation frequency and the difference between double high excitation frequency and low excitation frequency. In the latter region, however, the combination frequencies are dominated by the difference between high excitation frequency and double low excitation frequency and the difference between triple low excitation frequency and double high excitation frequency. Moreover, the motion of disk center shows a kind of ‘cross’, ‘soft Spring’ or ‘hard Spring’ Characteristics with the variation of the ratio of the two excitation frequencies. Besides, the independent quasi-periodic solution coexists with the periodic solution in these cases. The system is sensitive to the ratio of excitation frequencies, and it could have two independent quasi-periodic solutions in some conditions. The results in this paper provide a reveal of nonlinear Characteristics in this type of double excitation nonlinear rotor system.

Martijn Wisse - One of the best experts on this subject based on the ideXlab platform.

  • Unparameterized Optimization of the Spring Characteristic of Parallel Elastic Actuators
    IEEE Robotics and Automation Letters, 2019
    Co-Authors: Linda F. Van Der Spaa, Wouter J. Wolfslag, Martijn Wisse
    Abstract:

    In electrically actuated robots most energy losses are due to the heating of the actuators. This energy loss can be greatly reduced with parallel elastic actuators, by optimizing the elastic element such that it delivers most of the required torques. Previously used optimization methods relied on parameterizing the Spring Characteristic, thereby limiting the set of Spring Characteristics optimized over and with that the loss reduction that can be obtained. This letter shows that such parametrization is not necessary; a method is presented to compute the optimal Characteristic as an analytic function of the trajectory. The efficacy of this method is demonstrated using two examples. The first example considers the optimal Spring Characteristic for a parallel elastic actuator supporting the human ankle during walking. The second example applies the method in combination with trajectory optimization on a single degree of freedom robot performing a specific pick-and-place task. The task at hand has a height difference between the pick and the place location. With the analytical optimal Spring, it is shown that the robot can recover enough of the energy released by the package to function without external electric energy supply.

  • A novel Spring mechanism to reduce energy consumption of robotic arms
    2012 IEEE RSJ International Conference on Intelligent Robots and Systems, 2012
    Co-Authors: Michiel Plooij, Martijn Wisse
    Abstract:

    Most conventional robotic arms use motors to accelerate the manipulator. This leads to an unnecessary high energy consumption when performing repetitive tasks. This paper presents an approach to reduce energy consumption in robotic arms by performing its repetitive tasks with the help of a parallel Spring mechanism. A special non-linear Spring Characteristic has been achieved by attaching a Spring to two connected pulleys. This parallel Spring mechanism provides for the accelerations of the manipulator without compromising its ability to vary the task parameters (the time per stroke, the displacement per stroke the grasping time and the payload). The energy consumption of the arm with the Spring mechanism is compared to that of the same arm without the Spring mechanism. Optimal control studies show that the robotic arm uses 22% less energy due to the Spring mechanism. On the 2 DOF prototype, we achieved an energy reduction of 20%. The difference was due to model simplifications. With a Spring mechanism, there is an extra energetic cost, because potential energy has to be stored into the Spring during startup. This cost is equal to the total energy savings of the 2 DOF arm during 8 strokes. Next, there could have been an energetic cost to position the manipulator outside the equilibrium position. We have designed the Spring mechanism in such a way that this holding cost is negligible for a range of start- and end positions. The performed experiments showed that the implementation of the proposed Spring mechanism results in a reduction of the energy consumption while the arm is still able to handle varying task parameters.