scholarly journals Influence of Time Delay on Controlling the Non-Linear Oscillations of a Rotating Blade

Symmetry ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 85
Author(s):  
Yasser Salah Hamed ◽  
Ali Kandil
Keyword(s):  
Time Delay ◽  
Natural Frequency ◽  
Multiple Scales ◽  
Control Process ◽  
Control Force ◽  
Specific Level ◽  
Loop Control ◽  
Positive Displacement ◽  
Non Linear ◽  
Linear Vibrations

Time delay is an obstacle in the way of actively controlling non-linear vibrations. In this paper, a rotating blade’s non-linear oscillations are reduced via a time-delayed non-linear saturation controller (NSC). This controller is excited by a positive displacement signal measured from the sensors on the blade, and its output is the suitable control force applied onto the actuators on the blade driving it to the desired minimum vibratory level. Based on the saturation phenomenon, the blade vibrations can be saturated at a specific level while the rest of the energy is transferred to the controller. This can be done by adjusting the controller natural frequency to be one half of the blade natural frequency. The whole behavior is governed by a system of first-order differential equations gained by the method of multiple scales. Different responses are included to show the influences of time delay on the closed-loop control process. Also, a good agreement can be noticed between the analytical curves and the numerically simulated ones.

Design of a Simple Controller to Control Suspension Bridge Non-linear Vibrations due to Moving Loads

2005 ◽  
Vol 11 (7) ◽  
pp. 867-885 ◽  
Author(s):  
M. Abdel-Rohman
Keyword(s):  
Bridge Deck ◽  
Suspension Bridge ◽  
Suspension Bridges ◽  
Control Mechanisms ◽  
Control Force ◽  
Moving Loads ◽  
Non Linear ◽  
Linear Vibrations ◽  
Suspended Cables ◽  
Non Linear System

The flexibility and low damping of the long span suspended cables in suspension bridges make them prone to non-linear vibrations due to wind and moving loads. In this paper we consider the dynamic response of a suspension bridge due to a vertical load moving with a constant speed on the bridge deck. Control mechanisms are suggested to generate control forces to control the non-linear vibrations in the bridge deck and the suspended cables. A simple design is presented for the controller based on the feedback of the velocity measurements taken at the control force location. The design is made first on a linear model before applying it to the actual non-linear system. The method is applied on three different types of control mechanisms. Comparison between the controlled responses using the three controllers indicates that, in addition to the method of designing the control actions, the feasibility of the active control depends mainly on the type of the control mechanism.

Adaptive underslung beam using shape-memory alloys for frequency-tuning

2016 ◽  
Vol 28 (10) ◽  
pp. 1260-1271 ◽  
Author(s):  
Filipe Amarante dos Santos ◽  
Corneliu Cismaşiu
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Natural Frequency ◽  
Frequency Tuning ◽  
Control Process ◽  
Experimental Tests ◽  
Small Scale ◽  
Temperature Modulation ◽  
Loop Control ◽  
Control Approach

The present article addresses the study of an adaptive-passive beam structure with a shape-memory alloy based actuator. In order to mitigate adverse dynamic effects resulting from externally induced vibrations, the structure is able to automatically tune its natural frequency to avoid resonance. The adaptive-passive beam configuration is based on an underslung cable-stayed girder concept. Its frequency tuning is achieved by temperature modulation of the shape-memory alloy elements through a closed-loop control process based on a proportional-integral-derivative algorithm. The effectiveness of the proposed control solution is substantiated by numerical simulations and experimental tests on a small-scale prototype. The validated numerical model enables the simulation of the proposed control approach in a real-scale footbridge, subjected to a prescribed pedestrian loading. The results are very encouraging and show that, by activating the shape-memory alloy elements, the system is able to successfully shift its natural frequency and to mitigate the effects of induced vibrations.

Application of High Performance Electro-Hydraulic Synchronous Servo System on NC Broaching Machine

2013 ◽  
Vol 721 ◽  
pp. 497-500
Author(s):  
Guo Jin Chen ◽  
Jing Ni ◽  
Ting Ting Liu ◽  
Ming Xu
Keyword(s):  
High Performance ◽  
Control Process ◽  
Servo System ◽  
Numerical Control ◽  
Servo Drive ◽  
Loop Control ◽  
Performance Accuracy ◽  
Drive Control ◽  
Hydraulic Servo ◽  
Output Quantity

Aiming at the lower performance, accuracy and efficiency of the existing motion control process for the traditional broaching machine, the paper studies the high-performance dual-hydraulic synchronous servo drive control technology. The synchronous electro-hydraulic servo system forms the closed loop control by the detection and feedback of the output quantity. It eliminates and restrains largely the influence of the adverse factors to obtain the high-precision synchronous driving performance. The numerical control system based on the real-time error compensation and the intelligent control to the auxiliary machinery is developed. It is used for the CNC broaching machine to make the steady-state synchronous displacement error of the double cylinders be ≤ 0.5mm.

scholarly journals Robust Stabilization of Interval Plants with Uncertain Time-Delay Using the Value Set Concept

Mathematics ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 429
Author(s):  
Pedro Zamora ◽  
Alejandro Arceo ◽  
Noé Martínez ◽  
Gerardo Romero ◽  
Luis E. Garza
Keyword(s):  
Time Delay ◽  
Robust Stabilization ◽  
Parametric Uncertainty ◽  
Exclusion Principle ◽  
Control Synthesis ◽  
Classical Orthogonal Polynomials ◽  
Loop Control ◽  
Value Set ◽  
Interval Plants ◽  
Uncertain Time

This paper considers the robust stabilization problem for interval plants with parametric uncertainty and uncertain time-delay based on the value set characterization of closed-loop control systems and the zero exclusion principle. Using Kharitonov’s polynomials, it is possible to establish a sufficient condition to guarantee the robust stability property. This condition allows us to solve the control synthesis problem using conditions similar to those established in the loopshaping technique and to parameterize the controllers using stable polynomials constructed from classical orthogonal polynomials.

Non-linear vibrations of thick composite plates

1987 ◽  
Vol 115 (2) ◽  
pp. 367-371 ◽  
Author(s):  
G. Singh ◽  
Y.V.K. Sadasiva Rao
Keyword(s):  
Composite Plates ◽  
Non Linear ◽  
Linear Vibrations

NON-LINEAR VIBRATIONS OF A SLIGHTLY CURVED BEAM RESTING ON A NON-LINEAR ELASTIC FOUNDATION

1998 ◽  
Vol 212 (2) ◽  
pp. 295-309 ◽  
Author(s):  
H.R. Öz ◽  
M. Pakdemirli ◽  
E. Özkaya ◽  
M. Yilmaz
Keyword(s):  
Elastic Foundation ◽  
Curved Beam ◽  
Linear Elastic ◽  
Non Linear ◽  
Linear Vibrations

scholarly journals Perturbations of nonlinear autonomous oscillators

1994 ◽  
Vol 35 (4) ◽  
pp. 445-468 ◽  
Author(s):  
P. B. Chapman
Keyword(s):  
General Theory ◽  
Fourier Coefficients ◽  
Multiple Scales ◽  
Second Order ◽  
Multiple Scales Method ◽  
Suitable Parameter ◽  
Non Linear

AbstractA general theory is given for autonomous perturbations of non-linear autonomous second order oscillators. It is found using a multiple scales method. A central part of it requires computation of Fourier coefficients for representation of the underlying oscillations, and these coefficients are found as convergent expansions in a suitable parameter.

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