The structure parameters of 6-degree of freedom(DOF)vibration isolation platform have a significant effect on its performance.To make the designed vibration isolation platform perform well,non-dominanted sorting genet...The structure parameters of 6-degree of freedom(DOF)vibration isolation platform have a significant effect on its performance.To make the designed vibration isolation platform perform well,non-dominanted sorting genetic algorithm version II(NSGA-II)was applied to optimize its structure based on the transfer matrix method for multibody systems.Firstly,the Jacobian matrix of 6-DOF vibration isolation platform was solved based on kinematics.Secondly,the transfer equation of 6-DOF vibration isolation system was established by the linear transfer matrix method for multibody systems.And the formula of its natural frequency was derived according to the boundary conditions of the system.Thirdly,the manipulability index was constructed based on a dimensionless Jacobian matrix.And a new performance index function was established considering the influence of dynamic isotropic and legs mass.Fourthly,genetic algorithm(GA)and NSGA-II were used to optimize the structure of the 6-DOF vibration isolation platform under the same conditions,respectively.It showed that NSGA-II had higher optimization efficiency,better calculation accuracy and shorter optimization time than that of GA.Finally,NSGA-II was adopted for multi-objective optimization design of 6-DOF vibration isolation platform based on the constraint conditions.Optimal Pareto solutions were obtained,which provides structural parameters for subsequent design work.Therefore,the proposed optimization method and the performance index in this paper provide a theoretical basis for the optimal design of relevant vibration isolation mechanism.展开更多
Non-Gaussian random vibrations have gained more attention in the dynamics-research community due to the frequently encountered non-Gaussian dynamic environments in engineering practice.This work proposes a novel non-G...Non-Gaussian random vibrations have gained more attention in the dynamics-research community due to the frequently encountered non-Gaussian dynamic environments in engineering practice.This work proposes a novel non-Gaussian random vibration test method by simultaneous control of multiple correlation coefficients,skewness,and kurtoses.The multi-channel time-domain coupling model is first constructed which is mainly composed of the designed parameters and independent signal sources.The designed parameters are related to the defined correlation coefficients and root mean square values.The synthesized multiple non-Gaussian random signals are unitized to provide independent signal sources for coupling.The first four statistical characteristics of the synthesized non-Gaussian random signals are theoretically derived so that the relationships among the generated signals,independent signal sources,and correlation coefficients are achieved.Subsequently,a multi-channel closed-loop equalization procedure for non-Gaussian random vibration control is presented to produce a multi-channel correlated non-Gaussian random vibration environment.Finally,a simulation example and an experimental verification are provided.Results from the simulation and experiment indicate that the multi-channel response spectral densities,correlation coefficients,skewnesses,and kurtoses can be stably and effectively controlled within the corresponding tolerances by the proposed method.展开更多
To study the influence of temperature and internal leakage on the performance of magnetorheological(MR)damper,a single-rod straight-cylinder MR damper with an inside temperature sensor is designed in this study.A unif...To study the influence of temperature and internal leakage on the performance of magnetorheological(MR)damper,a single-rod straight-cylinder MR damper with an inside temperature sensor is designed in this study.A unified model for MR damper is given,and a new two-step parameters identification method is proposed to determine model parameters.The experiment,in which the damper is heated by long-time displacement excitation,is designed to study the effect of temperature and internal leakage.The influence mechanism of temperature and internal leakage on MR damper is analyzed through theoretical derivation and experimental results in this study.展开更多
基金supported by the National Natural Science Foundation of China(Grant 51975298)the Natural Science Foundation of Jiangsu Province(Grant BK20181301)the National Science Foundation of China(Grant 11874303).
文摘The structure parameters of 6-degree of freedom(DOF)vibration isolation platform have a significant effect on its performance.To make the designed vibration isolation platform perform well,non-dominanted sorting genetic algorithm version II(NSGA-II)was applied to optimize its structure based on the transfer matrix method for multibody systems.Firstly,the Jacobian matrix of 6-DOF vibration isolation platform was solved based on kinematics.Secondly,the transfer equation of 6-DOF vibration isolation system was established by the linear transfer matrix method for multibody systems.And the formula of its natural frequency was derived according to the boundary conditions of the system.Thirdly,the manipulability index was constructed based on a dimensionless Jacobian matrix.And a new performance index function was established considering the influence of dynamic isotropic and legs mass.Fourthly,genetic algorithm(GA)and NSGA-II were used to optimize the structure of the 6-DOF vibration isolation platform under the same conditions,respectively.It showed that NSGA-II had higher optimization efficiency,better calculation accuracy and shorter optimization time than that of GA.Finally,NSGA-II was adopted for multi-objective optimization design of 6-DOF vibration isolation platform based on the constraint conditions.Optimal Pareto solutions were obtained,which provides structural parameters for subsequent design work.Therefore,the proposed optimization method and the performance index in this paper provide a theoretical basis for the optimal design of relevant vibration isolation mechanism.
基金supported by the National Natural Science Foundation of China(Grant Nos.12202187,92266201 and 92266301)the Fundamental Research Funds for the Central Universities(Grant No.30924010819).
文摘Non-Gaussian random vibrations have gained more attention in the dynamics-research community due to the frequently encountered non-Gaussian dynamic environments in engineering practice.This work proposes a novel non-Gaussian random vibration test method by simultaneous control of multiple correlation coefficients,skewness,and kurtoses.The multi-channel time-domain coupling model is first constructed which is mainly composed of the designed parameters and independent signal sources.The designed parameters are related to the defined correlation coefficients and root mean square values.The synthesized multiple non-Gaussian random signals are unitized to provide independent signal sources for coupling.The first four statistical characteristics of the synthesized non-Gaussian random signals are theoretically derived so that the relationships among the generated signals,independent signal sources,and correlation coefficients are achieved.Subsequently,a multi-channel closed-loop equalization procedure for non-Gaussian random vibration control is presented to produce a multi-channel correlated non-Gaussian random vibration environment.Finally,a simulation example and an experimental verification are provided.Results from the simulation and experiment indicate that the multi-channel response spectral densities,correlation coefficients,skewnesses,and kurtoses can be stably and effectively controlled within the corresponding tolerances by the proposed method.
基金Jiangsu Funding Program for Excellent Postdoctoral Talent,Grant/Award Number:2022ZB276National Natural Science Foundation of China,Grant/Award Numbers:92166101,52305112Natural Science Foundation of Jiangsu Province,Grant/Award Number:BK20230906。
文摘To study the influence of temperature and internal leakage on the performance of magnetorheological(MR)damper,a single-rod straight-cylinder MR damper with an inside temperature sensor is designed in this study.A unified model for MR damper is given,and a new two-step parameters identification method is proposed to determine model parameters.The experiment,in which the damper is heated by long-time displacement excitation,is designed to study the effect of temperature and internal leakage.The influence mechanism of temperature and internal leakage on MR damper is analyzed through theoretical derivation and experimental results in this study.
