Sensitivity of Expected Exceedance Rate of SDOF-System Response to Statistical Uncertainties of Loading and System Parameters

1987 ◽  
pp. 471-486
Author(s):  
F. J. Wall ◽  
C. G. Bucher
Keyword(s):  
System Response ◽  
System Parameters ◽  
Sdof System

Numerical Investigation of Nonlinear Dynamics of a Pneumatic Artificial Muscle With Hard Excitation

2020 ◽  
Vol 15 (4) ◽  
Author(s):  
Bhaben Kalita ◽  
Santosha K. Dwivedy
Keyword(s):  
Nonlinear Dynamics ◽  
Resonance Condition ◽  
Basin Of Attraction ◽  
Artificial Muscle ◽  
Phase Portraits ◽  
System Response ◽  
Pneumatic Artificial Muscle ◽  
Superharmonic Resonance ◽  
System Parameters ◽  
Hard Excitation

Abstract In this work, a numerical analysis has been carried out to study the nonlinear dynamics of a system with pneumatic artificial muscle (PAM). The system is modeled as a single degree-of-freedom system and the governing nonlinear equation of motion has been derived to study the various responses of the system. The system is subjected to hard excitation and hence the subharmonic and superharmonic resonance conditions have been studied. The second-order method of multiple scales (MMS) has been used to find the response, stability, and bifurcations of the system. The effect of various system parameters on the system response has been studied using time response, phase portraits, and basin of attraction. In these responses, while the saddle node bifurcation is found in both super and subharmonic resonance conditions, the Hopf bifurcation is found only in superharmonic resonance condition. By changing different system parameters, it has been shown that the response with three periods leads to chaotic response for superharmonic resonance condition. This study will find applications in the design of PAM actuators.

Comparative Study of Evolutionary Algorithms for Parameter Identification of an Impact Oscillator

2014 ◽  
Author(s):  
Amit Banerjee ◽  
Issam Abu Mahfouz
Keyword(s):  
Evolutionary Algorithms ◽  
Differential Evolution ◽  
Parameter Identification ◽  
Optimization Techniques ◽  
System Response ◽  
Impact Oscillator ◽  
Swarm Optimization ◽  
System Parameters ◽  
Highly Nonlinear ◽  
The Impact

The use of non-classical evolutionary optimization techniques such as genetic algorithms, differential evolution, swarm optimization and genetic programming to solve the inverse problem of parameter identification of dynamical systems leading to chaotic states has been gaining popularity in recent years. In this paper, three popular evolutionary algorithms — differential evolution, particle swarm optimization and the firefly algorithm are used for parameter identification of a clearance-coupled-impact oscillator system. The behavior of impacting systems is highly nonlinear exhibiting a myriad of harmonic, low order and high order sub-harmonic resonances, as well as chaotic vibrations. The time-history simulations of the single-degree-of-freedom impact oscillator were obtained by the Neumark-β numerical integration algorithm. The results are illustrated by bifurcation graphs, state space portraits and Poincare’ maps which gives valuable insights on the dynamics of the impact system. The parameter identification problem relates to finding one set of system parameters given a chaotic or periodic system response as a set of Poincaré points and a different but known set of system parameters. The three evolutionary algorithms are compared over a set of parameter identification problems. The algorithms are compared based on solution quality to evaluate the efficacy of using one algorithm over another.

Modeling and Simulation of Stochastic Lorenz Systems by Polynomial Chaos Approach

2007 ◽  
Author(s):  
Lin Li ◽  
Corina Sandu
Keyword(s):  
Polynomial Chaos ◽  
Initial Conditions ◽  
Nonlinear Problems ◽  
System Response ◽  
Structural Vibrations ◽  
System Parameters ◽  
Highly Nonlinear ◽  
Body Dynamics ◽  
The Lorenz System ◽  
Multi Body

The Lorenz problem is one of the paradigms of the chaotic systems, which are sensitive to initial conditions and for which the performance is hard to predict. However, in many cases and dynamic systems, the initial conditions of a dynamic system and the system parameters can’t be measured accurately, and the response of the system must indeed be explored in advance. In this study, the polynomial chaos approach is used to handle uncertain initial conditions and system parameters of the Lorenz system. The method has been successfully applied by the authors and co-workers in multi-body dynamics and terrain profile and soil modeling. Other published studies illustrate the benefits of using the polynomial chaos, especially for problems involving large uncertainties and highly nonlinear problems in fluid mechanics, structural vibrations, and air quality studies. This study is an attempt to use the polynomial chaos approach to treat the Lorenz problem, and the results are compared with a classical Monte Carlo approach. Error bars are used to illustrate the standard deviation of the system response. Different meshing schemes are simulated, and the convergence of the method is analyzed.

Vibration Control of Horizontally Excited Structures Utilizing Internal Resonance of Liquid Sloshing in Nearly Square Tanks

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Takashi Ikeda ◽  
Yuji Harata
Keyword(s):  
Frequency Response ◽  
Internal Resonance ◽  
Passive Control ◽  
Harmonic Excitation ◽  
Liquid Sloshing ◽  
Maximum Efficiency ◽  
System Response ◽  
Response Curves ◽  
System Parameters ◽  
Theoretical Results

Passive control of vibrations in an elastic structure subjected to horizontal, harmonic excitation by utilizing a nearly square liquid tank is investigated. When the natural frequency ratio 1:1:1 is satisfied among the natural frequencies of the structure and the two predominant sloshing modes (1,0) and (0,1), the performance of a nearly square tank as a tuned liquid damper (TLD) is expected to be superior to rectangular TLDs due to internal resonance. In the theoretical analysis, Galerkin's method is used to determine the modal equations of motion for liquid sloshing considering the nonlinearity of sloshing. Then, van der Pol's method is used to obtain the expressions for the frequency response curves for the structure and sloshing modes. Frequency response curves and bifurcation set diagrams are shown to investigate the influences of the aspect ratio of the tank cross section and the tank installation angle on the system response. From the theoretical results, the optimal values of the system parameters can be determined in order to achieve maximum efficiency of vibration suppression for the structure. Hopf bifurcations occur and amplitude modulated motions (AMMs) may appear depending on the values of the system parameters. Experiments were also conducted, and the theoretical results agreed well with the experimental data.

Nonlinear Model and Simulation Experiment Research of Vibratory Rollers

2011 ◽  
Vol 121-126 ◽  
pp. 2121-2125
Author(s):  
Yuan Hao ◽  
Zhao Hui Ren ◽  
Feng Wen
Keyword(s):  
Nonlinear Vibration ◽  
Simulation Experiment ◽  
Response Characteristic ◽  
Soil Mass ◽  
System Model ◽  
System Response ◽  
Experiment Research ◽  
System Parameters ◽  
Model And Simulation ◽  
Excitation Force

On the basis of the relation between force and deformation when the plastic deformation of soil mass is studied, nonlinear vibration roller model is built. Based on one type vibratory rollers select the system parameters and calculate the natural frequency. And according to the selected numerical value proceed the numerical simulation with different excitation force frequencies. Meanwhile, obtain and analyze the experimental data according to the vibratory roller experiment. Then the system response characteristic of nonlinear vibration roller is obtained, and the availability of system model is checked. All above provide the valuable theoretical basis for the research of vibrating compacting.

scholarly journals Identification of Excitation Parameters Based on TLS - ESPRIT

2018 ◽  
Vol 228 ◽  
pp. 01015
Author(s):  
Guoqiang Xie ◽  
li Zou ◽  
Kansheng Yu ◽  
Jin Zou ◽  
Zhicheng Wang ◽  
...  
Keyword(s):  
Laplace Transform ◽  
Impulse Response ◽  
Least Squares Method ◽  
Matrix Pencil ◽  
System Response ◽  
A Algorithm ◽  
Excitation System ◽  
System Parameters ◽  
The Matrix ◽  
The Laplace Transform

In order to accurately detect excitation system parameters, this paper presents a algorithm based on the TLS-ESPRIT. The matrix pencil algorithm is used to extract the frequency and damping of each component of system response. So it’s necessary to apply the Laplace transform for s function of excitation system. After getting the Laplace transform of a function f(t), as mean as impulse response for excitation system. Then the magnitude and phase of each component of impulse response are estimated by least squares method, thus achieving the excitation system parameters. In the end, the simulation results show when SNR is between 35dB to 30dB, it still accurately identified the parameters.

Time-Frequency Characterization of a Cracked Rotor Sliding Bearing System With Rotor-Stator-Rub

2010 ◽  
Author(s):  
Alfayo A. Alugongo
Keyword(s):  
Sensitivity Analysis ◽  
Wavelet Transform ◽  
Condition Monitoring ◽  
System Response ◽  
Cracked Rotor ◽  
Sliding Bearings ◽  
Time Frequency ◽  
System Parameters ◽  
Bearing System

Constitutive dynamics of a cracked rotor supported on sliding bearings are modeled and analyzed by Wavelet Transform. The effect of the ensuing non-linear disturbances, namely, oil film forces, rotor stator rub forces, and a switching crack on the rotor shaft is numerically simulated. Subsequently, the system response is evaluated under various scenarios and the results reported. A sensitivity analysis on various system parameters is performed and discussed to emphasize the modeling. The current technique as a tool for condition monitoring of rotors has been demonstrated by analysis in this paper.

Parametric Identification of Nonlinear Systems Using Chaotic Excitation

2007 ◽  
Vol 2 (3) ◽  
pp. 225-231 ◽  
Author(s):  
M. D. Narayanan ◽  
S. Narayanan ◽  
Chandramouli Padmanabhan
Keyword(s):  
Time Series ◽  
Nonlinear Systems ◽  
Periodic Orbits ◽  
Parametric Identification ◽  
System Response ◽  
Unstable Periodic Orbits ◽  
Single Degree Of Freedom ◽  
System Parameters ◽  
Single Degree ◽  
Quadratic Damping

The use of a time series, which is the chaotic response of a nonlinear system, as an excitation for the parametric identification of single-degree-of-freedom nonlinear systems is explored in this paper. It is assumed that the system response consists of several unstable periodic orbits, similar to the input, and hence a Fourier series based technique is used to extract these nearly periodic orbits. Criteria to extract these orbits are developed and a least-squares problem for the identification of system parameters is formulated and solved. The effectiveness of this method is illustrated on a system with quadratic damping and a system with Duffing nonlinearity.

Analysis on the Effect of System Parameter on Double Cantilevers Vibro-Impact System Response

2012 ◽  
Vol 518-523 ◽  
pp. 3878-3886 ◽  
Author(s):  
Yu Rong Wang ◽  
Tian Xing Wu
Keyword(s):  
Dynamic Characteristics ◽  
Milling Process ◽  
System Response ◽  
Nonlinear Phenomena ◽  
Important Research ◽  
Instability Mechanism ◽  
System Parameters ◽  
Impact System ◽  
Practical Engineering ◽  
The Stability

The dynamic response of double cantilever vibro-impact system such as the stability of periodic motion, bifurcation etc., is an extremely important research content. However, the system dynamic characteristics are often influenced by the system parameters. Therefore, the theoretical modal of a double cantilevers vibro-impact system was established in this work, and the influence of clearance, damping and cubic nonlinear item on the dynamic characteristics of double cantilever vibro-impact system is detailedly analyzed through the numerical method .The results is helpful to analyze the practical engineering and to explore the nonlinear phenomena and the instability mechanism of the vibro-impact system such as milling process.

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