Confinement and Suppression of Structural Vibrations

2001 ◽  
Vol 123 (4) ◽  
pp. 496-501 ◽  
Author(s):  
Slim Choura ◽  
Ahmet S. Yigit
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Vibrational Energy ◽  
Flexible Structures ◽  
Element Model ◽  
Structural Vibrations ◽  
Feedback Strategy ◽  
Feedback Scheme ◽  
Vibratory Motion ◽  
Discretized Model

A feedback strategy, aiming at confining and suppressing simultaneously the vibratory motion in flexible structures, is proposed. It is assumed that the structure consists of parts that are sensitive to vibration. The proposed strategy makes use of control inputs whose number is less than or equal to that of the dimension of the discretized model. The design objective is to devise a feedback scheme that leads to transferring the vibrational energy from the sensitive parts to the remaining parts of the structure. In order to keep away from the build-up of transferred energy in the nonsensitive parts, the feedback scheme considers, along with the confinement, the suppression of vibration in both the sensitive and nonsensitive parts. The proposed strategy also accounts for the presence of persistent excitations. A finite element model of a cantilever beam is used to show the viability of the proposed strategy.

Confinement and Suppression of Structural Vibrations

2001 ◽  
Author(s):  
Slim Choura ◽  
Ahmet S. Yigit
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Vibrational Energy ◽  
Flexible Structures ◽  
Element Model ◽  
Structural Vibrations ◽  
Feedback Strategy ◽  
Feedback Scheme ◽  
Vibratory Motion ◽  
Discretized Model

Abstract A feedback strategy, aiming at confining and suppressing simultaneously the vibratory motion in flexible structures, is proposed. It is assumed that the structure consists of parts that are sensitive to vibration. The proposed strategy makes use of control inputs whose number is less than or equal to that of the dimension of the discretized model. The design objective is to devise a feedback scheme that leads to transferring the vibrational energy from the sensitive parts to the remaining parts of the structure. In order to keep away from the build-up of transferred energy in the nonsensitive parts, the feedback scheme considers, along with the confinement, the suppression of vibration in both the sensitive and non-sensitive parts. The proposed strategy also accounts for the presence of persistent excitations. A finite element model of a cantilever beam is used to show the viability of the proposed strategy.

Dynamic Analysis of Flexible Structures Using Component Mode Synthesis

1989 ◽  
Vol 56 (4) ◽  
pp. 874-880 ◽  
Author(s):  
M. De Smet ◽  
C. Liefooghe ◽  
P. Sas ◽  
R. Snoeys
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Degrees Of Freedom ◽  
Flexible Structures ◽  
Element Model ◽  
Component Mode Synthesis ◽  
Mode Shapes ◽  
Flexible Robot ◽  
Preliminary Calculation ◽  
Resonance Frequencies

In this paper a dynamic model of a flexible robot is built out of a finite element model of each of its links. The number of degrees-of-freedom of these models is strongly reduced by applying the Component Mode Synthesis technique which involves the preliminary calculation of a limited number of mode shapes of the separate links. As can be seen from examples, the type of boundary conditions thereby imposed in the nodes in which one link is connected to the others, strongly determines the accuracy of the calculated resonance frequencies of the robot. The method is applied to an industrial manipulator. The reduced finite element model of the robot is changed in order to match the numerically and experimentally (modal analysis) determined resonance data. Further, the influence of the position of the robot on its resonance frequencies is studied using the optimized numerical model.

scholarly journals Control of 2D Flexible Structures by Confinement of Vibrations and Regulation of Their Energy Flow

2009 ◽  
Vol 16 (2) ◽  
pp. 213-228 ◽  
Author(s):  
Fakhreddine Landolsi ◽  
Slim Choura ◽  
Ali H. Nayfeh
Keyword(s):  
Energy Flow ◽  
Vibrational Energy ◽  
Flexible Structures ◽  
Control Design ◽  
Control Law ◽  
Control Parameters ◽  
Feedback Strategy ◽  
Model Simulations ◽  
Suppression Process ◽  
Discretized Model

In this paper, we investigate the control of 2D flexible structures by vibration confinement and the regulation of their energy flow along prespecified spatial paths. A discretized-model-based feedback strategy, aiming at confining and suppressing simultaneously the vibration, is proposed. It is assumed that the structure consists of parts that are sensitive to vibrations. The control design introduces a new pseudo-modal matrix derived from the computed eigenvectors of the discretized model. Simulations are presented to show the efficacy of the proposed control law. A parametric study is carried out to examine the effects of the different control parameters on the simultaneous confinement and suppression of vibrations. In addition, we conducted a set of simulations to investigate the flow control of vibrational energy during the confinement-suppression process. We found that the energy flow can be regulated via a set of control parameters for different confinement configurations.

Analysis of the Influence of Blade Pattern Characteristics on the Forced Response of Mistuned Blisks With a Cyclic CMS-Based Substructure Model

2010 ◽  
Author(s):  
Andreas Hohl ◽  
Lars Panning ◽  
Jo¨rg Wallaschek
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Degrees Of Freedom ◽  
Vibrational Energy ◽  
Normal Modes ◽  
Element Model ◽  
Forced Response ◽  
Symmetry Approach ◽  
Full Structure ◽  
Value Decomposition

In turbomachinery applications bladed disks and blisks are subjected to high dynamic loads due to fluctuating gas forces. The dynamic excitation results in high vibration amplitudes which can lead to high cycle fatigue failures (HCF). Herein, the blades are almost identical but differ due to wear or small manufacturing tolerances. These small deviations of the blade properties can lead to a localization of the vibrational energy in single blades and even higher risk of HCF. Intentional mistuning, for example an alternating alignment of two different blades AB around the blisk, has been studied in literature to decrease the sensitivity against statistical mistuning. Using a Component Mode Synthesis (CMS) based mistuning model the influence of intentional mistuning on blisks is analyzed in this paper. Therein, the CMS of the disk is calculated with a fast and accurate cyclic symmetry approach. Therefore, the CMS of the disk can be calculated with one disk segment of the underlying Finite Element Model. The so called Wave Based Substructuring (WBS) is used to reduce the (numerous) coupling degrees of freedom between the disk and the blades with a truncated set of waves. The orthogonal waves are derived with a Singular Value Decomposition or a QR decomposition from the normal modes at the coupling degrees of freedom (DOF) calculated by a cyclic modal analysis of the full structure. In a case study the Reduced Order Model (ROM) of a spatial Finite Element Model is used to determine the influence of intentional mistuning with additional statistical mistuning on the forced response of blisks.

Finite Element Simulation of Tire-Rim Interface

1989 ◽  
Vol 17 (4) ◽  
pp. 305-325 ◽  
Author(s):  
N. T. Tseng ◽  
R. G. Pelle ◽  
J. P. Chang
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Finite Element Simulation ◽  
Contact Pressure ◽  
Element Model ◽  
Experimental Measurements ◽  
Inflation Pressure ◽  
Interference Fit ◽  
Element Simulation ◽  
Rubber Composite

Abstract A finite element model was developed to simulate the tire-rim interface. Elastomers were modeled by nonlinear incompressible elements, whereas plies were simulated by cord-rubber composite elements. Gap elements were used to simulate the opening between tire and rim at zero inflation pressure. This opening closed when the inflation pressure was increased gradually. The predicted distribution of contact pressure at the tire-rim interface agreed very well with the available experimental measurements. Several variations of the tire-rim interference fit were analyzed.

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