scholarly journals Algebraic Parameter Identification of Nonlinear Vibrating Systems and Non Linearity Quantification Using the Hilbert Transformation

2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Luis Gerardo Trujillo-Franco ◽  
Gerardo Silva-Navarro ◽  
Francisco Beltran-Carbajal
Keyword(s):  
Dynamic Performance ◽  
Differential Algebra ◽  
Operational Calculus ◽  
Mechanical Systems ◽  
Algebraic Approach ◽  
Parametric Identification ◽  
Hilbert Transformation ◽  
Orthogonal Functions ◽  
Matrix Operations ◽  
Specific Operating Condition

A novel algebraic scheme for parameters’ identification of a class of nonlinear vibrating mechanical systems is introduced. A nonlinearity index based on the Hilbert transformation is applied as an effective criterion to determine whether the system is dominantly linear or nonlinear for a specific operating condition. The online algebraic identification is then performed to compute parameters of mass and damping, as well as linear and nonlinear stiffness. The proposed algebraic parametric identification techniques are based on operational calculus of Mikusiński and differential algebra. In addition, we propose the combination of the introduced algebraic approach with signals approximation via orthogonal functions to get a suitable technique to be applied in embedded systems, as a digital signals’ processing routine based on matrix operations. A satisfactory dynamic performance of the proposed approach is proved and validated by experimental case studies to estimate significant parameters on the mechanical systems. The presented online identification approach can be extended to estimate parameters for a wide class of nonlinear oscillating electric systems that can be mathematically modelled by the Duffing equation.

On the Comparison of the Dynamic Performance of Open-Loop and Closed-Loop Mechanisms

2014 ◽  
Author(s):  
Jahangir Rastegar ◽  
Dake Feng
Keyword(s):  
Dynamic Response ◽  
Dynamic Systems ◽  
Closed Loop ◽  
Dynamic Performance ◽  
Mechanical Systems ◽  
Open Loop ◽  
Actuation Devices

In general, mechanical systems with closed-loop mechanisms can achieve significantly higher operating speeds as compared to open-loop mechanisms such as robots performing identical tasks. In this brief paper, the reason for the superior dynamic performance of closed-loop mechanisms as compared to open-loop mechanisms performing identical tasks is shown to be the inherent dynamic response limitations of the actuation devices in open-loop dynamic systems. Several examples are provided.

Efficient dynamic analysis of a whole aeroengine using identified nonlinear bearing models

2011 ◽  
Vol 226 (1) ◽  
pp. 66-81 ◽  
Author(s):  
K H Groves ◽  
P Bonello ◽  
P M Hai
Keyword(s):  
Dynamic Performance ◽  
Computational Cost ◽  
Parametric Identification ◽  
Frequency Domain Analysis ◽  
Reduced Form ◽  
Squeeze Film ◽  
Computational Time ◽  
Parameter Study ◽  
Accurate Identification ◽  
Non Linear

Essential to effective aeroengine design is the rapid simulation of the dynamic performance of a variety of engine and non-linear squeeze-film damper (SFD) bearing configurations. Using recently introduced non-linear solvers combined with non-parametric identification of high-accuracy bearing models it is possible to run full-engine rotordynamic simulations, in both the time and frequency domains, at a fraction of the previous computational cost. Using a novel reduced form of Chebyshev polynomial fits, efficient and accurate identification of the numerical solution to the two-dimensional Reynolds equation (RE) is achieved. The engine analysed is a twin-spool five-SFD engine model provided by a leading manufacturer. Whole-engine simulations obtained using Chebyshev-identified bearing models of the finite difference (FD) solution to the RE are compared with those obtained from the original FD bearing models. For both time and frequency domain analysis, the Chebyshev-identified bearing models are shown to mimic accurately and consistently the simulations obtained from the FD models in under 10 per cent of the computational time. An illustrative parameter study is performed to demonstrate the unparalleled capabilities of the combination of recently developed and novel techniques utilised in this paper.

Dynamic Intelligent Optimization Method of a Profiling Roll Forming Machine

2014 ◽  
Vol 1049-1050 ◽  
pp. 987-991
Author(s):  
Ai Fang Huang ◽  
Qiang Li
Keyword(s):  
Particle Swarm Optimization ◽  
Dynamic Performance ◽  
Mechanical Systems ◽  
Particle Swarm ◽  
Optimization Method ◽  
Operational Reliability ◽  
Roll Forming ◽  
Swarm Optimization ◽  
Intelligent Optimization ◽  
Application Fields

Profiling roll forming machine based on the theory of cold roll forming is a new equipment for sheet forming. A dynamic optimal design process for this machine can improve the operational reliability and dynamic response characters of its mechanical systems. Dynamic intelligent optimization method which is developing is very suitable to settle the problems of dynamic optimization for mechanical systems, and its application fields should be vigorously promoted. On account of the Particle Swarm Optimization has the advantages of easy understanding, easy realization and strong capability of global search, this paper decides to adopt the Particle Swarm Optimization combined with dynamic design. The method applied to mechanical systems of profiling roll forming machine is successful to optimize some relative parameters and improve the dynamic performance of the system.

An Optimization-Based Framework for Simultaneous Plant-Controller Redesign

1990 ◽  
Author(s):  
Robert Beyers ◽  
Subhas Desa
Keyword(s):  
Performance Improvement ◽  
Closed Loop ◽  
Optimization Problems ◽  
Dynamic Performance ◽  
Mechanical Systems ◽  
Loop System ◽  
Closed Loop System ◽  
Central Notion ◽  
Computer Controlled

Abstract In this paper we develop a framework for the redesign of computer-controlled, closed-loop, mechanical systems for improved dynamic performance. A central notion which underlies the redesign framework is that, in order to achieve the best possible performance from a constrained closed-loop system, the plant and controller should be designed simultaneously. The framework is presented as the formulation and solution of a progression of optimization problems which enable the designer to systematically establish the various redesign possibilities. An example clearly demonstrates the underlying ideas as well as the use of the redesign framework for performance improvement.

Vibration Reduction Performance of an Active Damping Control System for a Scaled System of a Cable-Stayed Bridge

2015 ◽  
Vol 15 (05) ◽  
pp. 1450077 ◽  
Author(s):  
Roberto Alvarado Cárdenas ◽  
Francisco Carrión Viramontes ◽  
Aarón Sariñana Toledo
Keyword(s):  
Control Method ◽  
Control Strategies ◽  
Dynamic Performance ◽  
Direct Synthesis ◽  
Parametric Identification ◽  
Active Damping ◽  
Scale Model ◽  
Damping Control ◽  
Physical Scale ◽  
Cable Vibrations

The main objective of this work is to develop an active damping system that can be used to reduce the vibrations of cables in stayed bridges. As a first stage, a laboratory physical scale model of a prestressed cable was used to characterize and test the dynamic performance of the damping system that comprises accelerometers to measure cable vibrations, an electromagnetic actuator which interacts with the cable to compensate for externally induced vibrations, and a digital controller in which control strategies and algorithms are defined. In the experiment, an additional actuator was used to excite vibration disturbances on the cable modifying its frequency and amplitude, and the location for the accelerometers was defined from simulations with a linear model of the cable to optimize the damping control method. Two different system identification approaches were used to calculate the frequency response function of the whole system (cable, accelerometers and actuators); the first approach used the spectral analysis to get initial dynamic results of the cable system, while the second employed the parametric identification to obtain the transfer function of the system, by which different models were assessed. Model reduction techniques and the direct synthesis approach were selected to get a second-order model for the controller. The active damping system was first evaluated with simulation studies and then, in the laboratory. Results show that the damping system reduces the vibration amplitude up to 50% for the resonance frequency. Complementary simulations using a full scale cable model of the stayed bridge with an equivalent active damping system, showed the same damping efficiency as for that in the laboratory experiment; however, a practical application must consider the scaling factor and the limitations of possible locations and orientations of the damping actuator to get the best dynamic performance.

Virtual Prototyping Simulation for Design of Mechanical Systems

1995 ◽  
Vol 117 (B) ◽  
pp. 63-70 ◽  
Author(s):  
E. J. Haug ◽  
K. K. Choi ◽  
J. G. Kuhl ◽  
J. D. Wargo
Keyword(s):  
System Design ◽  
Mechanical System ◽  
Driving Simulator ◽  
Dynamic Performance ◽  
Virtual Prototyping ◽  
Mechanical Systems ◽  
Design Sensitivity ◽  
Vehicle Design ◽  
Design Environment ◽  
Analysis And Design

Developments in simulation technology that enable a qualitatively new virtual prototyping approach to design of mechanical systems are summarized and their integration into an engineering design environment is illustrated. Simulation tools and their enabling technologies are presented in the context of vehicle design, with references to the literature provided. Their implementation for design representation, real-time driver-in-the-loop simulation, dynamic performance simulation, dynamic stress and life prediction, maintainability analysis, design sensitivity analysis, and design optimization is outlined. A testbed comprised of computer aided engineering tools and a design level of fidelity driving simulator that has been developed to demonstrate the feasibility of virtual prototyping simulation for mechanical system design is presented. Two 1994 demonstrations of this capability for vehicle design are presented, to illustrate the state of the technology and to identify challenges that remain in making virtual prototyping simulation an integral part of mechanical system design in US industry.

A Sequential Algebraic Parametric Identification Approach for Nonlinear Vibrating Mechanical Systems

2017 ◽  
Vol 19 (4) ◽  
pp. 1564-1574 ◽  
Author(s):  
F. Beltran-Carbajal ◽  
G. Silva-Navarro ◽  
L. G. Trujillo-Franco
Keyword(s):  
Mechanical Systems ◽  
Parametric Identification ◽  
Identification Approach
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