摘要:

AbstractAn adaptive tuned mass damper aiming to optimally increase the critical flow velocity of transverse galloping oscillations is presented. The structure, simply modeled as an elastically supported bluff body exposed to a steady flow, has been connected to an added mass by a spring and a dashpot varying according to an adaptive control algorithm. Based on the knowledge of a reference model, describing the optimal conditions for the system, the paper presents two procedures to design a controller that allows to identify the uncertain mechanical parameters relying on a direct and an indirect approach. In the direct case, by assuring the convergency to zero of the error between the system and the reference model variables, in the indirect case, by using a wavelet based approach for on‐line system identification. The analytical developments are validated by numerical investigations on the nonlinear system in order to assess the feasibility of the proposed control syste

ISSN:1122-8385    

DOI:10.1002/stc.4300060201

出版商:John Wiley&Sons, Ltd    

年代:1999

数据来源: WILEY

摘要:

AbstractTwo different optimal control strategies defined in the frequency domain are discussed in this paper. The general formulation of H2and H∞is reorganized in an easy way to be used for mechanical applications. Both the control methodologies are reviewed for general problems and applied to simple systems by showing their main mechanical aspects and differences. The two methods have been numerically compared in controlling the seismic response of a base isolated system equipped with a hybrid mass dampe

ISSN:1122-8385    

DOI:10.1002/stc.4300060202

出版商:John Wiley&Sons, Ltd    

年代:1999

数据来源: WILEY

摘要:

AbstractIn the Danish part of the North Sea monopile platforms with a cylindrical shaft have been used at the exploitation of marginal fields. In the paper a new principle for active vibration control of such structures is suggested. The principle is based on a control of the boundary layer flow around the cylinder of the platform, so the drag force in the generalized Morison equation is increased whenever it is acting in the opposite direction of the cylinder motion, whereas an unchanged drag force is applied, whenever it is acting co‐directionally to the cylinder motion. The inertial force of the wave load is not subjected to control. The increased drag force is obtained by forcing the boundary layers to separate by blowing air into the boundary layer from the inside through small holes in the cylinder surface placed at a relatively large distance from the water surface. The control is specified by the sign of the fluid velocity relative to the platform, and only this quantity need to be measured, which is easily performed by a flow meter fixed to the platform. The efficiency of the described closed loop control system has been verified by model tests in a wave flume in both regular and irregular wave conditions, where reductions in the vibration level of up to 50% have been registere

ISSN:1122-8385    

DOI:10.1002/stc.4300060203

出版商:John Wiley&Sons, Ltd    

年代:1999

数据来源: WILEY

摘要:

AbstractIn this paper a research activity, aimed at verifying the possibility of designing active vibration control systems based on piezoelectric devices, is reported. A full analogic controller has been developed to suppress the vibrations in a clamped rectangular flat panel using piezoceramic patches. Vibration reduction tests and their correlations to numerical predictions, based on an integrated piezo‐structural model, are presented. Only simple co‐located direct feed‐back laws have been used to point out problems related to measurements. Self sensing actuators were also tested. The correlation with numerical prediction shows that the adopted approach is capable of supplying a suitable design

ISSN:1122-8385    

DOI:10.1002/stc.4300060204

出版商:John Wiley&Sons, Ltd    

年代:1999

数据来源: WILEY

ISSN:1122-8385    

DOI:10.1002/stc.4300060205

出版商:John Wiley&Sons, Ltd    

年代:1999

数据来源: WILEY

ISSN:1122-8385    

DOI:10.1002/stc.4300060206

出版商:John Wiley&Sons, Ltd    

年代:1999

数据来源: WILEY