A new model for a raft isolation system is proposed, in which the raft supports two ma- chines on a flexible foundation via a series of isolators. The interaction between the flexible floating raft and the non-rigid f...A new model for a raft isolation system is proposed, in which the raft supports two ma- chines on a flexible foundation via a series of isolators. The interaction between the flexible floating raft and the non-rigid foundation is studied by the novel approach of power flow. The power flow input and transmitted in the complicated compound system are then formulated in closed forms, in which the coupling between the raft and the foundation is considered . The effect of the raft flexibili- ty on power flow spectra is also revcaled. This study shows that it may lead to an overoptimistic evaluation to the effectiveness of the raft isolation when simplifying the raft to an ideal rigid struc- ture. Thereby, the reliable estimation and effective design for raft isolation system are provided.展开更多
For estimating the vibration transmission accurately and performing vibration control efficiently in isolation systems, a novel general model is presented to predict the power flow transmitted into the complicate flex...For estimating the vibration transmission accurately and performing vibration control efficiently in isolation systems, a novel general model is presented to predict the power flow transmitted into the complicate flexible bases of laminated beams. In the model, the laminated beam bases are simulated by the first-order shear deformation laminated plate theory, which is relatively simple and economic but accurate in predicting the vibration solutions of flexible isolation systems with laminated beam bases in comparison with classical laminated beam theories and higher order theories. On the basis of the presented model, substructure technique and variational principle are employed to obtain the governing equation of the isolation system and the power flow solution. Then, the vibration characteristics of the flexible isolation systems with laminated bases are investigated. Several numerical examples are given to show the validity and efficiency of the presented model. It is concluded that the presented model is the extension of the classical one and it can obtain more accurate power flow solutions.展开更多
Passive-active control of a flexible isolation system is investigated from the viewpoint of power flow. Dynamic transfer equations of the system are deduced based on a matrix method which uses mobility or impedance re...Passive-active control of a flexible isolation system is investigated from the viewpoint of power flow. Dynamic transfer equations of the system are deduced based on a matrix method which uses mobility or impedance representations of three substructures: the source of vibration, the receiver and the mounting system which connects the source to the receiver. The cancellation of axial input forces to the receiver is considered as the active control strategy and its effects are discussed. The results of the study show that the strategy adopted herein can effectively reduce the power transmitted to the receiver.展开更多
The transmision mechanism of vibrational power flow in the complex flekible coupled system of machinery mouned on a multi-storey plant building via isolators are studied in this paper from the viewpoint of energy. In ...The transmision mechanism of vibrational power flow in the complex flekible coupled system of machinery mouned on a multi-storey plant building via isolators are studied in this paper from the viewpoint of energy. In view of practical isolation designs in engineering,an asymmetric isolation system with mtiltiple isolators on a fiekible foundation is modeled, in which the interactions between the machine and the floor, and among different mouating points are taken illto account. Moreover, the transmission characteristics of power flow in the system concerned are analyzed with the use of subsystem mobility synthetic techaique. Further more,the power flow spectra of the asymmetric system are calculated and compared with those of symmetric one to reveal the effects of asymmetricity and system parameters on the power flow.Finally, new approaches to the control of structural vibration and acoustics for this kin of problems are proposed.展开更多
现代机械的高速化和轻量化的发展趋势导致了更加严重的振动噪声问题,因此柔性系统的高频隔振降噪是机械设计过程中必须要考虑的问题。充分考虑机械系统的柔性性质,采用子结构导纳综合法和传递矩阵技术,建立多激励多支承的柔性机器和柔...现代机械的高速化和轻量化的发展趋势导致了更加严重的振动噪声问题,因此柔性系统的高频隔振降噪是机械设计过程中必须要考虑的问题。充分考虑机械系统的柔性性质,采用子结构导纳综合法和传递矩阵技术,建立多激励多支承的柔性机器和柔性基础(Flexible machine and flexible base,FMFB)全柔性隔振系统的一般动力学模型和力学描述,该模型不但包含了刚性机器和刚性基础(Rigid machine and rigid base,RMRB)、刚性机器和柔性基础(Rigid machine and flexible base,RMFB)、柔性机器和刚性基础(Flexible machine and rigid base,FMRB)等多种隔振模型,而且还可以借助该模型分析积极隔振和被动隔振等问题。通过系统综合,给出适合于不同隔振系统的传递率和功率流表达式,探讨各类柔性系统的固有频率耦合规律,并研究它们的振动传递特性等问题,得到了一些有价值的结论,对柔性隔振设计具有重要的指导意义。展开更多
文摘A new model for a raft isolation system is proposed, in which the raft supports two ma- chines on a flexible foundation via a series of isolators. The interaction between the flexible floating raft and the non-rigid foundation is studied by the novel approach of power flow. The power flow input and transmitted in the complicated compound system are then formulated in closed forms, in which the coupling between the raft and the foundation is considered . The effect of the raft flexibili- ty on power flow spectra is also revcaled. This study shows that it may lead to an overoptimistic evaluation to the effectiveness of the raft isolation when simplifying the raft to an ideal rigid struc- ture. Thereby, the reliable estimation and effective design for raft isolation system are provided.
基金supported by National Natural Science Foundation of China (Grant No. 50805088)China Postdoctoral Science Foundation (No.2004035223)
文摘For estimating the vibration transmission accurately and performing vibration control efficiently in isolation systems, a novel general model is presented to predict the power flow transmitted into the complicate flexible bases of laminated beams. In the model, the laminated beam bases are simulated by the first-order shear deformation laminated plate theory, which is relatively simple and economic but accurate in predicting the vibration solutions of flexible isolation systems with laminated beam bases in comparison with classical laminated beam theories and higher order theories. On the basis of the presented model, substructure technique and variational principle are employed to obtain the governing equation of the isolation system and the power flow solution. Then, the vibration characteristics of the flexible isolation systems with laminated bases are investigated. Several numerical examples are given to show the validity and efficiency of the presented model. It is concluded that the presented model is the extension of the classical one and it can obtain more accurate power flow solutions.
基金National Natural Science Foundation of China (No.50275085)
文摘Passive-active control of a flexible isolation system is investigated from the viewpoint of power flow. Dynamic transfer equations of the system are deduced based on a matrix method which uses mobility or impedance representations of three substructures: the source of vibration, the receiver and the mounting system which connects the source to the receiver. The cancellation of axial input forces to the receiver is considered as the active control strategy and its effects are discussed. The results of the study show that the strategy adopted herein can effectively reduce the power transmitted to the receiver.
文摘The transmision mechanism of vibrational power flow in the complex flekible coupled system of machinery mouned on a multi-storey plant building via isolators are studied in this paper from the viewpoint of energy. In view of practical isolation designs in engineering,an asymmetric isolation system with mtiltiple isolators on a fiekible foundation is modeled, in which the interactions between the machine and the floor, and among different mouating points are taken illto account. Moreover, the transmission characteristics of power flow in the system concerned are analyzed with the use of subsystem mobility synthetic techaique. Further more,the power flow spectra of the asymmetric system are calculated and compared with those of symmetric one to reveal the effects of asymmetricity and system parameters on the power flow.Finally, new approaches to the control of structural vibration and acoustics for this kin of problems are proposed.
文摘现代机械的高速化和轻量化的发展趋势导致了更加严重的振动噪声问题,因此柔性系统的高频隔振降噪是机械设计过程中必须要考虑的问题。充分考虑机械系统的柔性性质,采用子结构导纳综合法和传递矩阵技术,建立多激励多支承的柔性机器和柔性基础(Flexible machine and flexible base,FMFB)全柔性隔振系统的一般动力学模型和力学描述,该模型不但包含了刚性机器和刚性基础(Rigid machine and rigid base,RMRB)、刚性机器和柔性基础(Rigid machine and flexible base,RMFB)、柔性机器和刚性基础(Flexible machine and rigid base,FMRB)等多种隔振模型,而且还可以借助该模型分析积极隔振和被动隔振等问题。通过系统综合,给出适合于不同隔振系统的传递率和功率流表达式,探讨各类柔性系统的固有频率耦合规律,并研究它们的振动传递特性等问题,得到了一些有价值的结论,对柔性隔振设计具有重要的指导意义。
