scholarly journals Assessment of a rolling isolation system using reduced order structural models

2015 ◽  
Vol 99 ◽  
pp. 708-725 ◽  
Author(s):  
P. Scott Harvey ◽  
Henri P. Gavin
Keyword(s):  
Structural Models ◽  
Isolation System ◽  
Reduced Order

Development of an aeroelastic model based on system identification using boundary elements method

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Rohollah Dehghani Firouz-Abadi ◽  
Mohammad Reza Borhan Panah
Keyword(s):  
Boundary Element Method ◽  
Boundary Element ◽  
Structural Models ◽  
Elastic Mode ◽  
Content Type ◽  
Reduced Order ◽  
Aerodynamic Model ◽  
Aeroelastic Model ◽  
Proposed Model ◽  
Element Method

Purpose The purpose of this paper is to analyze the stability of aeroelastic systems using a novel reduced order aeroelastic model. Design/methodology/approach The proposed aeroelastic model is a reduced-order model constructed based on the aerodynamic model identification using the generalized aerodynamic force response and the unsteady boundary element method in various excitation frequency values. Due to the low computational cost and acceptable accuracy of the boundary element method, this method is selected to determine the unsteady time response of the aerodynamic model. Regarding the structural model, the elastic mode shapes of the shell are used. Findings Three case studies are investigated by the proposed model. In the first place, a typical two-dimensional section is introduced as a means of verification by approximating the Theodorsen function. As the second test case, the flutter speed of Advisory Group for Aerospace Research and Development 445.6 wing with 45° sweep angle is determined and compared with the experimental test results in the literature. Finally, a complete aircraft is considered to demonstrate the capability of the proposed model in handling complex configurations. Originality/value The paper introduces an algorithm to construct an aeroelastic model applicable to any unsteady aerodynamic model including experimental models and modal structural models in the implicit and reduced order form. In other words, the main advantage of the proposed method, further to its simplicity and low computational effort, which can be used as a means of real-time aeroelastic simulation, is its ability to provide aerodynamic and structural models in implicit and reduced order forms.

Modeling and Control of Active Vibration Isolation System Taking the Dynamics of Elastic Load Into Account by Using the Reduced Order Physical Model

2011 ◽  
Author(s):  
Keisuke Sudo ◽  
Toru Watanabe ◽  
Kazuto Seto
Keyword(s):  
Vibration Isolation ◽  
Isolation System ◽  
Vibration Isolation System ◽  
Modeling And Control ◽  
Reduced Order ◽  
Elastic Load ◽  
Active Isolation ◽  
Lq Optimal Control ◽  
Active Vibration ◽  
And Control

This paper deals with the control system design for active isolation table[1][2][3]. It aims at controlling vibration of the installed object and isolation table. An experimental isolation table with flexible loaded object is built. Control simulations are carried out by using feedback controller designed according to LQ optimal control theory.

Detection and Isolation of Faults in Mobile Hydraulic Valves Based on a Reduced-Order Model and Adaptive Thresholds

2013 ◽  
Author(s):  
Jarmo Nurmi ◽  
Jouni Mattila
Keyword(s):  
Fault Detection ◽  
Open Loop ◽  
Reduced Order Model ◽  
Fault Detection And Isolation ◽  
Order Model ◽  
Isolation System ◽  
Reduced Order ◽  
Adaptive Thresholds ◽  
Hydraulic Valves ◽  
Hydraulic Valve

Detecting and isolating faults in complex engineering systems is important for properly planning maintenance, and it leads to decreases in down and repair times and to an increase in system performance. Mobile hydraulic valves, which are characterized by functions such as pressure-compensation and pilot-operation, are such complex systems that they could tremendously benefit from a real-time, accurate fault detection and isolation system. However, the complexity of these valves means that accurate full-state modeling is generally difficult and time-consuming. This paper proposes a reduced-order model for the fault detection of an open-loop-controlled mobile hydraulic valve. This reduced-order model is used along with statistically computed adaptive thresholds for the purpose of enhancing the reliability of fault detection. The considered faults include valve spool jamming caused by hydraulic fluid impurities, leakages caused by wear-induced increased clearances between the valve spool and sleeve, and sensor faults. The reduced-order model omits the modeling of pressure compensator dynamics by using a measurement of the pressure compensator, and pilot pressure dynamics by measuring the pilot pressures that drive the main spool. Experimental results from a commercial mobile hydraulic valve controlling a 2-DOF hydraulic crane show the practicality of the reduced-order modeling and adaptive threshold arrangements in this fault detection task. As a downside, a reduced set of faults can be isolated with the reduced-order model, but as a future consideration a bigger set of fault patterns with a full model are given and compared with the results obtained.

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