This present paper deals with a mathematical description of linear axial and torsional vibrations. The normal and tangential stress tensor components produced by axial-torsional deformations and vibrations in the prop...This present paper deals with a mathematical description of linear axial and torsional vibrations. The normal and tangential stress tensor components produced by axial-torsional deformations and vibrations in the propeller and intermediate shafts, under the influence of propeller-induced static and variable hydrodynamic excitations are also studied. The transfer matrix method related to the constant coefficients of differential equation solutions is used. The advantage of the latter as compared with a well-known method of transfer matrix associated with state vector is the possibility of reducing the number of multiplied matrices when adjacent shaft segments have the same material properties and diameters. The results show that there is no risk of buckling and confirm that the strength of the shaft line depends on the value of the static tangential stresses which is the most important component of the stress tensor.展开更多
To investigate the repeated frequency condition (RFC) for torsional vibration of shafts' system, the transfer matrix method was adopted. Firstly, the transfer relationship from the boundary to engaging disks of do...To investigate the repeated frequency condition (RFC) for torsional vibration of shafts' system, the transfer matrix method was adopted. Firstly, the transfer relationship from the boundary to engaging disks of double shafts' system (DSS) was constructed. Secondly, the RFC of DSS was deduced out and the methods to select mode shape were presented. Finally, the relationship was extended to multilevel transmission system (MTS), and the RFC of this system was explored. The conclusions is this: 1) the necessary RFC requires the existence of joint engaging couple (JEC); 2) for DSS, the sufficient is the number of boundary transfer factors (f(B)) larger than 2; 3) the whale system can be split into independent groups, the total multiplicity is the sum of independent solution number of every group, the latter is the number of independent f(B), = 0 inside the group minus 1.展开更多
According to the theoretical analysis and calculation on the base ofcontinuous mass system, the simulation experimental investigation on active control of torsionalvibration in a turbogenerator shaft system is conduct...According to the theoretical analysis and calculation on the base ofcontinuous mass system, the simulation experimental investigation on active control of torsionalvibration in a turbogenerator shaft system is conducted. A test installation with the excitation ofgenerator motor and multi-stepped shaft system is established to simulate the torsional vibration ofa turbogenerator rotor shaft system, and to examine the active control strategy presented. Someuseful results are reached in the experimental study.展开更多
The torsional oscillation characteristics on the bending and torsioh coupled vibration of rotary shaft system were investigated using the elasto-dynamic theory and other mathematic methods, such as difference approach...The torsional oscillation characteristics on the bending and torsioh coupled vibration of rotary shaft system were investigated using the elasto-dynamic theory and other mathematic methods, such as difference approach, Fourier transform, and wavelet transform. It is concluded that mass eccentricity and other exciting modalities affect the bending and torsion coupled vibration of rotary shafts. Torsional vibration caused by bending vibration features linearity along with the change of amplitude of bending vibration. Meanwhile, energy spectrum concentrates on high frequency area with the wavelet analysis.展开更多
传统线性减振器在抑制内燃机轴系的扭转振动方面有着长期的应用,但较窄的减振带宽限制了其性能的发挥.考虑到内燃机闭环轴系的周期性激振力随转速的变化而变化,其在相对较宽的频率域内实现高效的减振十分必要.为了探究非线性能量阱(nonl...传统线性减振器在抑制内燃机轴系的扭转振动方面有着长期的应用,但较窄的减振带宽限制了其性能的发挥.考虑到内燃机闭环轴系的周期性激振力随转速的变化而变化,其在相对较宽的频率域内实现高效的减振十分必要.为了探究非线性能量阱(nonlinear energy sink,NES)替代调谐质量阻尼器(tuned mass damper,TMD)抑制曲轴扭转振动的可行性,文章将建立曲轴的多惯量非线性闭环自激耦合振荡模型,在此基础上,研究TMD和NES对闭环曲轴扭振减振的影响规律.分析过程综合考虑了轴系不同轴段位置的瞬态和稳态扭转振动.除此之外,定义了振动密度,性能领先效率和波动率3种函数综合考虑不同动力吸振器(dynamic vibration absorber,DVA)的性能优劣.讨论了NES和TMD在不同的设计参数下(变刚度、变阻尼和变位置排布)的减振效率和鲁棒性.结果表明,NES和TMD控制曲轴扭振时具有不同的刚度及阻尼失效区间.随着设计参数的变化,NES和TMD的减振性能交替领先,NES的综合性能领先了24.5%,TMD的综合性能领先了3.3%.同时,NES具有较高的阻尼依赖性(13.6%),TMD具有较高的刚度(3.6%)及位置依赖性(25.6%).展开更多
为有效控制输电塔的有害振动需要了解其振动特性,提出一种惯性测量数据矩阵模式的输电塔振动分析方法。将微惯性测量单元(Micro-Inertia-Measurement-Unit,MIMU)安装在输电塔上通过Kalman滤波预处理三轴原始数据,重构权重奇异值分解(Wei...为有效控制输电塔的有害振动需要了解其振动特性,提出一种惯性测量数据矩阵模式的输电塔振动分析方法。将微惯性测量单元(Micro-Inertia-Measurement-Unit,MIMU)安装在输电塔上通过Kalman滤波预处理三轴原始数据,重构权重奇异值分解(Weighted Singular Value Decomposition,WSVD)后的相干振动分量建立平动/扭动矩阵。提取矩阵序列中的变换矩阵,计算其Frobenius范数度量暂态振动间的变异度来估计幅值与频率。根据幅频参数计算振动耗能,观测输电塔各轴向以及整体的振动情况。最后设计振动台、转台实验验证振动数据处理方法的有效性,并对不同风荷载下的塔线模型与真型风振试验进行特性分析。结果表明输电塔振动以水平方向的平动形式为主,随风向夹角的增大其非线性效应逐渐增强,所提出的数据处理方法能够有效获得振动信息,可为控制有害振动的阻尼器的设计提供参考。展开更多
In order to solve fretting instability problem of gear shaft shoulder due to torsional vibration in mechanical system, the mathematical model of fretting instability vibration of gear shaft shoulder was established by...In order to solve fretting instability problem of gear shaft shoulder due to torsional vibration in mechanical system, the mathematical model of fretting instability vibration of gear shaft shoulder was established by adopting the method of combining kinematics and tribology, and the numerical analysis was applied to the fretting instability mechanism of gear shaft shoulder by introducing the friction instability damping ratio. The numerical results show that the main factors causing the unstable and vibrating gear shaft shoulder are the large tightening torque and too large static friction coefficient. The reasonable values of the static friction coefficient, the amount of interference and tightening torque can effectively mitigate the fretting instability phenomenon of gear shaft shoulder. The experimental results verify that damping plays a significant role in eliminating the vibration of gear shaft control system.展开更多
文摘This present paper deals with a mathematical description of linear axial and torsional vibrations. The normal and tangential stress tensor components produced by axial-torsional deformations and vibrations in the propeller and intermediate shafts, under the influence of propeller-induced static and variable hydrodynamic excitations are also studied. The transfer matrix method related to the constant coefficients of differential equation solutions is used. The advantage of the latter as compared with a well-known method of transfer matrix associated with state vector is the possibility of reducing the number of multiplied matrices when adjacent shaft segments have the same material properties and diameters. The results show that there is no risk of buckling and confirm that the strength of the shaft line depends on the value of the static tangential stresses which is the most important component of the stress tensor.
文摘To investigate the repeated frequency condition (RFC) for torsional vibration of shafts' system, the transfer matrix method was adopted. Firstly, the transfer relationship from the boundary to engaging disks of double shafts' system (DSS) was constructed. Secondly, the RFC of DSS was deduced out and the methods to select mode shape were presented. Finally, the relationship was extended to multilevel transmission system (MTS), and the RFC of this system was explored. The conclusions is this: 1) the necessary RFC requires the existence of joint engaging couple (JEC); 2) for DSS, the sufficient is the number of boundary transfer factors (f(B)) larger than 2; 3) the whale system can be split into independent groups, the total multiplicity is the sum of independent solution number of every group, the latter is the number of independent f(B), = 0 inside the group minus 1.
基金This project is supported by National Natural Science Foundation of China (No.59575015) Education Ministry of China.
文摘According to the theoretical analysis and calculation on the base ofcontinuous mass system, the simulation experimental investigation on active control of torsionalvibration in a turbogenerator shaft system is conducted. A test installation with the excitation ofgenerator motor and multi-stepped shaft system is established to simulate the torsional vibration ofa turbogenerator rotor shaft system, and to examine the active control strategy presented. Someuseful results are reached in the experimental study.
基金SUPPORTED BY NATIONAL NATURAL SCIENCE FOUNDATION OF CHINA( NO. 50475112)NATURAL SCIENCE FOUNDATION OF TIANJIN (NO. 043601411).
文摘The torsional oscillation characteristics on the bending and torsioh coupled vibration of rotary shaft system were investigated using the elasto-dynamic theory and other mathematic methods, such as difference approach, Fourier transform, and wavelet transform. It is concluded that mass eccentricity and other exciting modalities affect the bending and torsion coupled vibration of rotary shafts. Torsional vibration caused by bending vibration features linearity along with the change of amplitude of bending vibration. Meanwhile, energy spectrum concentrates on high frequency area with the wavelet analysis.
文摘传统线性减振器在抑制内燃机轴系的扭转振动方面有着长期的应用,但较窄的减振带宽限制了其性能的发挥.考虑到内燃机闭环轴系的周期性激振力随转速的变化而变化,其在相对较宽的频率域内实现高效的减振十分必要.为了探究非线性能量阱(nonlinear energy sink,NES)替代调谐质量阻尼器(tuned mass damper,TMD)抑制曲轴扭转振动的可行性,文章将建立曲轴的多惯量非线性闭环自激耦合振荡模型,在此基础上,研究TMD和NES对闭环曲轴扭振减振的影响规律.分析过程综合考虑了轴系不同轴段位置的瞬态和稳态扭转振动.除此之外,定义了振动密度,性能领先效率和波动率3种函数综合考虑不同动力吸振器(dynamic vibration absorber,DVA)的性能优劣.讨论了NES和TMD在不同的设计参数下(变刚度、变阻尼和变位置排布)的减振效率和鲁棒性.结果表明,NES和TMD控制曲轴扭振时具有不同的刚度及阻尼失效区间.随着设计参数的变化,NES和TMD的减振性能交替领先,NES的综合性能领先了24.5%,TMD的综合性能领先了3.3%.同时,NES具有较高的阻尼依赖性(13.6%),TMD具有较高的刚度(3.6%)及位置依赖性(25.6%).
文摘为有效控制输电塔的有害振动需要了解其振动特性,提出一种惯性测量数据矩阵模式的输电塔振动分析方法。将微惯性测量单元(Micro-Inertia-Measurement-Unit,MIMU)安装在输电塔上通过Kalman滤波预处理三轴原始数据,重构权重奇异值分解(Weighted Singular Value Decomposition,WSVD)后的相干振动分量建立平动/扭动矩阵。提取矩阵序列中的变换矩阵,计算其Frobenius范数度量暂态振动间的变异度来估计幅值与频率。根据幅频参数计算振动耗能,观测输电塔各轴向以及整体的振动情况。最后设计振动台、转台实验验证振动数据处理方法的有效性,并对不同风荷载下的塔线模型与真型风振试验进行特性分析。结果表明输电塔振动以水平方向的平动形式为主,随风向夹角的增大其非线性效应逐渐增强,所提出的数据处理方法能够有效获得振动信息,可为控制有害振动的阻尼器的设计提供参考。
基金Project(2008AA11A116)supported by the National High Technology Research and Development Program of ChinaProject(9140A2011QT4801)supported by advanced research of the Weapon Equipment Key Fund Program,ChinaProject(61075002)supported by the Independent Subject of State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body of Hunan University,China
文摘In order to solve fretting instability problem of gear shaft shoulder due to torsional vibration in mechanical system, the mathematical model of fretting instability vibration of gear shaft shoulder was established by adopting the method of combining kinematics and tribology, and the numerical analysis was applied to the fretting instability mechanism of gear shaft shoulder by introducing the friction instability damping ratio. The numerical results show that the main factors causing the unstable and vibrating gear shaft shoulder are the large tightening torque and too large static friction coefficient. The reasonable values of the static friction coefficient, the amount of interference and tightening torque can effectively mitigate the fretting instability phenomenon of gear shaft shoulder. The experimental results verify that damping plays a significant role in eliminating the vibration of gear shaft control system.
