作为转子系统的一个常见故障,转子和定子之间的碰摩导致转子系统表现出很强的非线性。因此,从具有碰摩故障的转子系统中获得的振动信号包含微弱的高阶非线性成分,这些成分很难用传统的线性方法进行表征。非线性输出频率响应函数(nonline...作为转子系统的一个常见故障,转子和定子之间的碰摩导致转子系统表现出很强的非线性。因此,从具有碰摩故障的转子系统中获得的振动信号包含微弱的高阶非线性成分,这些成分很难用传统的线性方法进行表征。非线性输出频率响应函数(nonlinear output frequency response functions,NOFRFs)是一种在频域上分析非线性系统的有效方法,现已被许多学者应用于非线性系统的故障诊断。文中引入Kullback-Leibler(KL)散度的概念,提出了一种基于KL散度改进的NOFRFs加权贡献率(NWKL)的新方法。并在此方法中提出一个新指标—基于KL散度的改进的NOFRFs最优加权贡献率(KLRm),用以评估转子系统中碰摩故障的严重程度。通过转子系统仿真分析和实验验证,表明NWKL方法对转子系统碰摩故障具有很高的适用性和有效性。并且指标KLRm对于不对中故障具有很高的灵敏度,它可以全面地表征转子系统的非线性特性。该方法在转子碰摩的检测和评价中具有重要的意义和潜在的应用价值。展开更多
A novel vibration isolation device called the nonlinear energy sink(NES)with NiTiNOL-steel wire ropes(NiTi-ST)is applied to a whole-spacecraft system.The NiTi-ST is used to describe the damping of the NES,which is cou...A novel vibration isolation device called the nonlinear energy sink(NES)with NiTiNOL-steel wire ropes(NiTi-ST)is applied to a whole-spacecraft system.The NiTi-ST is used to describe the damping of the NES,which is coupled with the modified Bouc-Wen model of hysteresis.The NES with NiTi-ST vibration reduction principle uses the irreversibility of targeted energy transfer(TET)to concentrate the energy locally on the nonlinear oscillator,and then dissipates it through damping in the NES with NiTi-ST.The generalized vibration transmissibility,obtained by the root mean square treatment of the harmonic response of the nonlinear output frequency response functions(NOFRFs),is first used as the evaluation index to analyze the whole-spacecraft system in the future.An optimization analysis of the impact of system responses is performed using different parameters of NES with NiTi-ST based on the transmissibility of NOFRFs.Finally,the effects of vibration suppression by varying the parameters of NiTi-ST are analyzed from the perspective of energy absorption.The results indicate that NES with NiTi-ST can reduce excessive vibration of the whole-spacecraft system,without changing its natural frequency.Moreover,the NES with NiTi-ST can be directly used in practical engineering applications.展开更多
In order to improve the harsh dynamic environment experienced by heavy rockets during different external excitations,this study presents a novel active variable stiffness vibration isolator(AVS-VI)used as the vibratio...In order to improve the harsh dynamic environment experienced by heavy rockets during different external excitations,this study presents a novel active variable stiffness vibration isolator(AVS-VI)used as the vibration isolation device to reduce excessive vibration of the whole-spacecraft isolation system.The AVS-VI is composed of horizontal stiffness spring,positive stiffness spring,parallelogram linkage mechanism,piezoelectric actuator,acceleration sensor,viscoelastic damping,and PID active controller.Based on the AVS-VI,the generalized vibration transmissibility determined by the nonlinear output frequency response functions and the energy absorption rate is applied to analyze the isolation performance of the whole-spacecraft system with AVS-VI.The AVS-VI can conduct adaptive vibration suppression with variable stiffness to the whole-spacecraft system,and the analysis results indicate that the AVS-VI is efTective in reducing the extravagant vibration of the whole-spacecraft system,where the vibration isolation is decreased up to above 65%under different acceleration excitations.Finally,different parameters of AVS-VI are considered to optimize the whole-spacecraft system based on the generalized vibration transmissibility and the energy absorption rate.展开更多
文摘作为转子系统的一个常见故障,转子和定子之间的碰摩导致转子系统表现出很强的非线性。因此,从具有碰摩故障的转子系统中获得的振动信号包含微弱的高阶非线性成分,这些成分很难用传统的线性方法进行表征。非线性输出频率响应函数(nonlinear output frequency response functions,NOFRFs)是一种在频域上分析非线性系统的有效方法,现已被许多学者应用于非线性系统的故障诊断。文中引入Kullback-Leibler(KL)散度的概念,提出了一种基于KL散度改进的NOFRFs加权贡献率(NWKL)的新方法。并在此方法中提出一个新指标—基于KL散度的改进的NOFRFs最优加权贡献率(KLRm),用以评估转子系统中碰摩故障的严重程度。通过转子系统仿真分析和实验验证,表明NWKL方法对转子系统碰摩故障具有很高的适用性和有效性。并且指标KLRm对于不对中故障具有很高的灵敏度,它可以全面地表征转子系统的非线性特性。该方法在转子碰摩的检测和评价中具有重要的意义和潜在的应用价值。
基金Project supported by the National Natural Science Foundation of China(No.11772205)the Scientific Research Fund of Liaoning Provincial Education Department(No.L201703)+1 种基金the Liaoning Revitalization Talent Program(No.XLYC1807172)the Training Project of Liaoning Higher Education Institutions in Domestic and Overseas(No.2018LNGXGJWPY-YB008)
文摘A novel vibration isolation device called the nonlinear energy sink(NES)with NiTiNOL-steel wire ropes(NiTi-ST)is applied to a whole-spacecraft system.The NiTi-ST is used to describe the damping of the NES,which is coupled with the modified Bouc-Wen model of hysteresis.The NES with NiTi-ST vibration reduction principle uses the irreversibility of targeted energy transfer(TET)to concentrate the energy locally on the nonlinear oscillator,and then dissipates it through damping in the NES with NiTi-ST.The generalized vibration transmissibility,obtained by the root mean square treatment of the harmonic response of the nonlinear output frequency response functions(NOFRFs),is first used as the evaluation index to analyze the whole-spacecraft system in the future.An optimization analysis of the impact of system responses is performed using different parameters of NES with NiTi-ST based on the transmissibility of NOFRFs.Finally,the effects of vibration suppression by varying the parameters of NiTi-ST are analyzed from the perspective of energy absorption.The results indicate that NES with NiTi-ST can reduce excessive vibration of the whole-spacecraft system,without changing its natural frequency.Moreover,the NES with NiTi-ST can be directly used in practical engineering applications.
基金the National Natural Science Foundation of China(Project Nos.12022213,11772205 and 11902203)the Scieatifie Research Fund of Liaoning Provineinl Education Department(No.L201703)+1 种基金the Program of Liaoning Revitalization Talents(XLYC1807172)the Tralning Project of Liaoning Higher Education Institutions in Domestic and Oveseas(Nos.2018LNGXGJWPY-YB008).
文摘In order to improve the harsh dynamic environment experienced by heavy rockets during different external excitations,this study presents a novel active variable stiffness vibration isolator(AVS-VI)used as the vibration isolation device to reduce excessive vibration of the whole-spacecraft isolation system.The AVS-VI is composed of horizontal stiffness spring,positive stiffness spring,parallelogram linkage mechanism,piezoelectric actuator,acceleration sensor,viscoelastic damping,and PID active controller.Based on the AVS-VI,the generalized vibration transmissibility determined by the nonlinear output frequency response functions and the energy absorption rate is applied to analyze the isolation performance of the whole-spacecraft system with AVS-VI.The AVS-VI can conduct adaptive vibration suppression with variable stiffness to the whole-spacecraft system,and the analysis results indicate that the AVS-VI is efTective in reducing the extravagant vibration of the whole-spacecraft system,where the vibration isolation is decreased up to above 65%under different acceleration excitations.Finally,different parameters of AVS-VI are considered to optimize the whole-spacecraft system based on the generalized vibration transmissibility and the energy absorption rate.
