| Summary: | 碩士 === 淡江大學 === 土木工程學系碩士班 === 97 === Flutter is one of the aero-elastic behaviors in the wind-induced motion of cross-section structure. The conventional approach for identifying flutter derivatives of cross-section structure is to use the free vibration method which has disadvantages, such as lack of consistency due to high sensitivity of free vibration response to the test condition/environment, and the error inherited by treating free vibration frequency as excitation frequency. In order to overcome these shortcomings, In this study the use of indirect methods forced vibration test. First, given by the servo motor vibration platform for forced vibration, structural model cross-section through the spring disturbance, and then measured in a smooth flow in each system under the aero-elastic response.
Experimental identification process is divided into structural parameters (mass, stiffness, damping) and the derivative identification (non-coupled flutter derivatives identified and coupled flutter derivatives to identify, explore the direction of the horizontal and reverse direction
Which the derivative identified by the system aero-elastic response of the transfer function in each experimental value and theoretical value, in the frequency domain in order to curve fitting optimization to identify the best parameters of type theory, end up with cross-section model of the flutter derivatives . One reference in the theoretical part of the concept of the state-space equation to derive, and the best process by invoking the genetic algorithm to solve in order to secure the global optimal solution.
In this paper, four different cross-section model as an example, the use of Tamkang University''s civil engineering laboratory wind-tunnel experiments the above-mentioned identification results can be cylindrical cross-section of non-derivative and coupled vibration vibration of non-coupled bridge deck flutter derivatives and coupled flutter derivatives, its cylindrical cross-section of the flutter derivatives and Scanlan to compare the theory of style, while the trend of close to show indirect forced vibration identification method to identify flutter derivatives. One coupling width / depth ratio of 27 sections, in the analysis yet to be more precise, in order to more accurately identify the flutter derivatives.
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