scholarly journals High-Fidelity Fin–Actuator System Modeling and Aeroelastic Analysis Considering Friction Effect

2021 ◽  
Vol 11 (7) ◽  
pp. 3057
Author(s):  
Jin Lu ◽  
Zhigang Wu ◽  
Chao Yang
Keyword(s):  
System Modeling ◽  
Past Research ◽  
High Fidelity ◽  
Aeroelastic Stability ◽  
Aeroelastic Analysis ◽  
Structural Nonlinearities ◽  
Flutter Boundary ◽  
Actuator System ◽  
Friction Models ◽  
Comparison Of The Results

Both the dynamic characteristics and structural nonlinearities of an actuator will affect the flutter boundary of a fin–actuator system. The actuator models used in past research are not universal, the accuracy is difficult to guarantee, and the consideration of nonlinearity is not adequate. Based on modularization, a high-fidelity modeling method for an actuator is proposed in this paper. This model considers both freeplay and friction, which is easy to expand. It can be directly used to analyze actuator characteristics and perform aeroelastic analysis of fin–actuator systems. Friction can improve the aeroelastic stability, but the mechanism of its influence on the aeroelastic characteristics of the system has not been reported. In this paper, the LuGre model, which can better reflect the friction characteristics, was integrated into the actuator. The influence of the initial condition, freeplay, and friction on the aeroelastic characteristics of the system was analyzed. The comparison of the results with the previous research shows that oversimplified friction models are not accurate enough to reflect the mechanism of friction’s influence. By changing the loads, material, and geometry of contact surfaces, flutter can be effectively suppressed, and the power loss caused by friction can be minimized.

Linear and Nonlinear Aeroelastic Analysis of a High Aspect Ratio Wing

2017 ◽  
Author(s):  
F. Bakhtiari-Nejad ◽  
A. H. Modarres ◽  
E. H. Dowell ◽  
H. Shahverdi
Keyword(s):  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Structural Model ◽  
State Space Model ◽  
Beam Model ◽  
Aeroelastic Analysis ◽  
Structural Nonlinearities ◽  
Flutter Boundary ◽  
Linear And Nonlinear ◽  
Perturbation Equations

In this study, analysis and results of linear and nonlinear aeroelastic of a cantilever beam subjected to the airflow as a model of a high aspect ratio wing are presented. A third-order nonlinear beam model is used as structural model to take into account the effects of geometric structural nonlinearities. In order to model aerodynamic loads, Wagner state-space model has been used. Galerkin method is implemented to solve dynamic perturbation equations about a nonlinear static equilibrium state. The small perturbation flutter boundary is determined by these perturbation equations. The effect of geometric structural nonlinearity of the beam model on the flutter behavior is significant. As it is observed the system’s response to upper speed of flutter goes to limit cycle oscillations and also the oscillations lose periodicity and become chaotic.

Training Techniques for Developing Trust in Virtual Teams

2011 ◽  
pp. 1659-1666
Author(s):  
Peggy M. Beranek ◽  
Ben Martz ◽  
Monique French
Keyword(s):  
Organizational Performance ◽  
Virtual Teams ◽  
Communication Systems ◽  
Computer Mediated Communication ◽  
Past Research ◽  
Mediated Communication ◽  
Team Members ◽  
Face To Face ◽  
Computer Mediated ◽  
Comparison Of The Results

Trust among team members is a major factor influencing the cohesiveness of the group, trust also has a direct impact on team performance, problem solving, organizational performance, and organizational communication. Virtual teams are teams in which members are distributed and communicate via computer-mediated communication systems (CMCS). Past research has indicated that the development of trust among team members requires face-to-face communication, thereby making it difficult for virtual teams to develop trust. Recent research has shown that it is possible to train virtual teams to exhibit higher levels of trust. This paper describes and discusses different methods of trust training for virtual teams. We offer a comprehensive comparison of the results and analysis of the training programs of these studies and offer advice on developing and conducting such programs.

Optimal Control Theory Applied to a Pump With Single-Stage Electrohydraulic Servovalve

1988 ◽  
Vol 110 (2) ◽  
pp. 120-125 ◽  
Author(s):  
A. Akers ◽  
S. J. Lin
Keyword(s):  
Optimal Control ◽  
Control Theory ◽  
Optimal Control Theory ◽  
System Modeling ◽  
Control Valve ◽  
Open Loop ◽  
Single Stage ◽  
Response Curves ◽  
Electrohydraulic Valve ◽  
Comparison Of The Results

Optimal control theory is applied to the design of a pressure regulator for an axial piston pump and single-stage electrohydraulic valve combination. The control valve has been modeled and an optimal control law has been formulated. The time response curves due to a step input inflow rate and in current input to the servovalve have been obtained for the open loop and for the optimal control system. Comparison of the results has been made with previous work in which the supply valve to the swashplate actuators was not modeled. It is shown that controlled system modeling of the servovalve significantly improves system performance in terms of response frequency and pressure peaks.

Wave-Based Control of a Nonlinear Flexible System

2006 ◽  
Author(s):  
William J. O’Connor ◽  
Francisco Ramos ◽  
Vicente Feliu
Keyword(s):  
Control Strategies ◽  
System Modeling ◽  
Nonlinear Behavior ◽  
Effective Control ◽  
Space Structures ◽  
Large Space ◽  
Flexible System ◽  
Strongly Nonlinear ◽  
Mechanical Waves ◽  
Actuator System

The motivation for this work is the control of flexible mechanical systems, such as long, light robot arms, gantry cranes, and large space structures, with an actuator at one end and a free boundary at the other. Very effective control strategies have recently been developed which are based on interpreting the actuator motion as launching mechanical “waves” (propagating motion) into the flexible system while absorbing returning “waves”. These control systems are robust to system changes and to actuator limitations. They are generic, require very little system modeling, need only local sensing, and are computationally light and easy to implement. In a flexible arm, when elastic deflections are large, frequently there is strongly nonlinear behavior. This paper investigates how such nonlinearities affect the wave-based control strategy. In summary, the news is good. It is found that errors arise only when trajectories are very demanding, and even then the errors are small. Some strategies for correcting these errors are explained: addition of a linear element at the actuator-system interface, error correction by second manoeuver, and redefinition of the waves in a less-than-optimal way. The paper presents these ideas and illustrates them with numerical simulations.

scholarly journals A linear aerodynamics-based preconditioner for high-fidelity aeroelastic analysis and sensitivity analysis

2016 ◽  
Author(s):  
Kristofer Jovanov ◽  
Roeland De Breuker ◽  
Mostafa M. Abdalla ◽  
Christophe Blondeau
Keyword(s):  
Sensitivity Analysis ◽  
High Fidelity ◽  
Aeroelastic Analysis

Aeroelastic analysis through linear and non-linear methods: a summary of flutter prediction in the PUMA DARP

2006 ◽  
Vol 110 (1107) ◽  
pp. 333-343 ◽  
Author(s):  
N. V. Taylor ◽  
C. B. Allen ◽  
A. L. Gaitonde ◽  
D. P. Jones ◽  
G. A. Vio ◽  
...  
Keyword(s):  
Excellent Agreement ◽  
Dynamic Behaviour ◽  
Test Cases ◽  
Wing Design ◽  
Pressure Distributions ◽  
Aeroelastic Analysis ◽  
Coupled Codes ◽  
Non Linear ◽  
Flutter Boundary

AbstractThis paper presents a comparison of linear and non-linear methods for the analysis of aeroelastic behaviour and flutter boundary prediction. The methods in question include NASTRAN and ZAERO, based on linear aerodynamics, and the non-linear coupled CFD-CSD methods RANSMB and PMB, developed at the Universities of Bristol and Glasgow respectively. The test cases used for this comparison are the MDO and AGARD 445.6 weakened wing. In general, it was found that the non-linear methods demonstrate excellent agreement with respect to pressure distributions, deflections, dynamic behaviour, and flutter boundary locations for both cases. This is in contrast to previous studies involving similar methods, where notable differences across the MDO span were found, and is taken to imply good performance of the CFD-CSD interpolation schemes employed here. While the linear methods produce similar flutter boundaries to the coupled codes for the aerodynamically simple AGARD 445.6 wing, results for the transonic ‘rooftop’ MDO wing design did not agree as well.

scholarly journals Research and Analysis of Automated Special Machine for Fastening of U-Frame and Screw

2019 ◽  
Vol 8 (12S) ◽  
pp. 192-195
Keyword(s):  
Material Handling ◽  
Simulation Analysis ◽  
System Modeling ◽  
Circuit Breaker ◽  
Serial Transfer ◽  
Special Machine ◽  
Actuator System ◽  
Increase Productivity ◽  
Automated Material Handling ◽  
And Control

This paper introduces the Design, Modeling and Simulation of a special tool that attaches a screw to attach the screw to a bimetal of MCB (Miniature Circuit Breaker). Problems found in the current process include complex shape and screw size and full connection operation is an intensive manual operation which makes handling difficult for the operator and also the size of the M2 screw and is headless with a cross section. In partnership with the SPM operator works as a tool to increase productivity by reducing operator fat. The system is a testament to automated material handling system, serial transfer, trap detection, attachment, automatic ejecting system, actuator system, sensors and control capabilities etc. Small screw handling and bike prospect are the major challenges in the special development of a purpose screw attachment system. System Modeling & Simulation analysis is done and the results are encouraging.

AEROELASTIC PHENOMENA OF FLIGHT VEHICLES IN TRANSONIC REGION

2009 ◽  
Vol 23 (03) ◽  
pp. 421-424
Author(s):  
IN LEE ◽  
JONG-YUN KIM ◽  
KYUNG-SEOK KIM ◽  
IN-GYU LIM
Keyword(s):  
Structural Dynamics ◽  
Critical Problem ◽  
Flight Vehicles ◽  
Aeroelastic Analysis ◽  
Structural Nonlinearities ◽  
Computational Structural Dynamics ◽  
Computational Fluid Dynamics Cfd ◽  
Analysis System ◽  
Transonic Region ◽  
Coupled Techniques

Flight vehicles experience aeroelastic problems due to the interaction between structures and aerodynamic forces. Aeroelastic instability is usually a critical problem in transonic and lower supersonic regions. In present study, the aeroelastic analyses of several flight vehicles have been performed using the coupled techniques of computational fluid dynamics (CFD) and computational structural dynamics (CSD). The aeroelastic characteristics based on several aircraft models are investigated using the developed aeroelastic analysis system. On the other hand, structural nonlinearities always exist in flight vehicles. Structural nonlinearities such as freeplay and large deformation effects are considered in the present aeroelastic analysis system. Finally, aeroelastic characteristics of several flight vehicles will be explained considering both aerodynamic and structural nonlinearities.

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