Frequency control and its effect on the dynamic response of flexible structures

AIAA Journal ◽  
1985 ◽  
Vol 23 (11) ◽  
pp. 1768-1774 ◽  
Author(s):  
Vipperla B. Venkayya ◽  
Victoria A. Tischler
Keyword(s):  
Dynamic Response ◽  
Frequency Control ◽  
Flexible Structures

scholarly journals The Dynamic Response of Tuned Impact Absorbers for Rotating Flexible Structures

2005 ◽  
Vol 1 (1) ◽  
pp. 13-24 ◽  
Author(s):  
Steven W. Shaw ◽  
Christophe Pierre
Keyword(s):  
Dynamic Response ◽  
Flexible Structures ◽  
Experimental Studies ◽  
Analytical Investigation ◽  
Design Parameters ◽  
System Response ◽  
Rotor Speed ◽  
Flexible System ◽  
Restoring Forces ◽  
And Performance

This paper describes an analytical investigation of the dynamic response and performance of impact vibration absorbers fitted to flexible structures that are attached to a rotating hub. This work was motivated by experimental studies at NASA, which demonstrated the effectiveness of these types of absorbers for reducing resonant transverse vibrations in periodically excited rotating plates. Here we show how an idealized model can be used to describe the essential dynamics of these systems, and used to predict absorber performance. The absorbers use centrifugally induced restoring forces so that their nonimpacting dynamics are tuned to a given order of rotation, whereas their large amplitude dynamics involve impacts with the primary flexible system. The linearized, nonimpacting dynamics are first explored in detail, and it is shown that the response of the system has some rather unique features as the hub rotor speed is varied. A class of symmetric impacting motions is also analyzed and used to predict the effectiveness of the absorber when operating in its impacting mode. It is observed that two different types of grazing bifurcations take place as the rotor speed is varied through resonance, and their influence on absorber performance is described. The analytical results for the symmetric impacting motions are also used to generate curves that show how important absorber design parameters—including mass, coefficient of restitution, and tuning—affect the system response. These results provide a method for quickly evaluating and comparing proposed absorber designs.

Aerodynamic Damping and Fluid-Structure Interaction of Blast Loaded Flexible Structures

2011 ◽  
Vol 82 ◽  
pp. 491-496
Author(s):  
Martien Teich ◽  
Norbert Gebbeken ◽  
Martin Larcher
Keyword(s):  
Dynamic Response ◽  
Fluid Structure Interaction ◽  
Flexible Structures ◽  
Blast Loads ◽  
Damping Term ◽  
Damping Force ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Aerodynamic Damping ◽  
Compliant Systems

This paper analyses the e ects of air-structure interaction of systems subjectedto weak blast loads. While these coupling e ects are negligible for typical steel or concretestructures, they may dominate the dynamic response of lighter and more exible (compliant)systems like membranes, blast curtains or cable facades. For these light and exible systems,a classical decoupled analysis, i.e., neglecting the inuence of the surrounding air, might sig-ni cantly overestimate the deections and strains. However, we show that the coupling e ectscan be accounted for by basically adding a viscous aerodynamic damping force. We discussand compare two approaches how to obtain the aerodynamic damping term. With decreasingstructural sti ness and mass, the damping contribution of air increases signi cantly. The resultsof Hydrocode simulations are presented, and an outlook into further areas of research is given.

Deregulated LFC scheme using equilibrium optimized Type-2 fuzzy controller

2021 ◽  
pp. 494-505
Author(s):  
Pulakraj Aryan ◽  
Mrinal Ranjan ◽  
Ravi Shankar
Keyword(s):  
Dynamic Response ◽  
Power System ◽  
Fuzzy Controller ◽  
Frequency Control ◽  
Load Frequency Control ◽  
Proportional Integral Derivative ◽  
Proportional Integral ◽  
Deregulated Power System ◽  
Interval Type

This paper deals about the Load Frequency Control (LFC) of two-area deregulated power system with multiple generation sources using interval type-2 fuzzy proportional-integral-derivative (IT2FPID) controller. LFC is the mechanism by which the power system tries to restore its nominal frequency after it has been subjected to load fluctuations. The control areas considered for this paper comprise of thermal generating unit with reheat turbine and gas unit. Considering practical scenario of operation appropriate generation rate constraint (GRC) has been considered for each units. The gain parameters of IT2FPID controller have been optimized by Equilibrium Optimizer (EO). The dynamic response to load disturbances have been compared with prevalent controller schemes to bring about the efficacy of the prospective work.

scholarly journals Robust and adaptable dynamic response reshaping of flexible structures

2020 ◽  
Vol 468 ◽  
pp. 115086
Author(s):  
Valentin Preda ◽  
Francesco Sanfedino ◽  
Samir Bennani ◽  
Fabrice Boquet ◽  
Daniel Alazard
Keyword(s):  
Dynamic Response ◽  
Flexible Structures

Efficient Response Monitoring of Flexible Structures

2014 ◽  
Author(s):  
Maria Chierichetti ◽  
Vahid Rahneshin
Keyword(s):  
Dynamic Response ◽  
Flexible Structures ◽  
Numerical Approach ◽  
Initial Guess ◽  
Response Monitoring ◽  
Entire Body ◽  
Simple Task ◽  
Full Field ◽  
Flexible System ◽  
Applied Forces

The definition of an accurate model to represent the dynamic behavior of a flexible system has a significant impact on the understanding of its current health. However, due to lack of information on the physical properties as well as complexity of applied loads, accurate modeling is not usually a simple task, and inaccuracies in predicting the response of the flexible structure arise. In this work, a combined experimental and numerical approach, called Extended Load Confluence Algorithm (ELCA), is presented to improve the accuracy in the estimate of the dynamic response using an iterative approach that corrects the initial model. The objective is to accurately estimate the displacements, strains, and accelerations of the entire body. The full-field dynamic response is reconstructed from a limited set of experimental data, with little knowledge about the applied loads. ELCA estimates the state of the structure by defining fictitious applied forces that depend on the error of the estimate. The proposed algorithm is based on an initial numerical model for the prediction of the system s behavior. This model is updated based on a modal expansion of the response in the frequency domain. The algorithm starts with an initial guess of the applied loads and updates them in few iterations in order to match the numerical dynamic response with the experimental measurements at the sensors locations. Numerical and experimental analyses will show the feasibility of the proposed approach. It will be shown that a few sensors are sufficient to represent the overall behavior of the system and ELCA converges in a few iterations.

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