Search results for "Linear"
showing 10 items of 7165 documents
Creep Modeling with Time-Dependent Damping Parameters in Piezoelectric Actuators
2019
This paper develops a creep model based on the Kelvin-Voigt model with time varying damping parameters. In the piezoelectric actuators, the creep phenomenon is an important issue in precise positioning applications as well as the hysteresis property. It is well-known that the creep effect can be represented by a series connection of a number of Kelvin-Voigt elements as a viscoelastic model. In the motion for the continuous stepwise positioning, however, the creep shape is different for each response. Since the phenomenon can be captured as temporal creep relaxation, time-dependent damping parameters are introduced to improve the reproducibility of the creep for the various motion. On the ot…
A New Technique for Vibration-Based Diagnostics of Fatigued Structures Based on Damage Pattern Recognition via Minimization of Misclassification Prob…
2017
Vibration-based diagnostics provide various methods to detect, locate, and characterize damage in structural and mechanical systems by examining changes in measured vibration response. Research in vibration-based damage recognition has been rapidly expanding over the last few years. The basic idea behind this technology is that modal parameters (notably frequencies, mode shapes, and modal damping) are functions of the physical properties of the structure (mass, damping, and stiffness). Therefore, changes in the physical properties will cause detectable changes in the modal properties. In investigations, many techniques were applied to recognize damage in structural and mechanical systems, b…
Non-Homogeneous Tension Profile
2013
In this chapter, we will look at the influence of a skewed tension profile on the divergence instability of a travelling, thin elastic plate. The travelling plate is subjected to axial tension at the supports, but the tension distribution along the supports is not uniform. For the nonuniformity, we will use a linear distribution. First, we will perform a dynamic analysis of small time-harmonic vibrations, after which we will concentrate on the divergence instability problem. We will see that a small inhomogeneity in the applied tension may have a large effect on the divergence modes, and that inhomogeneity in the tension profile may significantly decrease the critical velocity of the plate.
Vibrations and oscillations of tri-soliton molecules in a mode-locked fiber laser
2018
We present numerical simulations highlighting internal oscillations and vibrations within tri-soliton molecules generated by a mode-locked fiber laser. We highlight major qualitative differences as compared to two-soliton molecules.
Travelling Strings, Beams, Panels, Membranes and Plates
2013
In this chapter, we will introduce in a general manner some of the most common models for axially travelling materials, which will be used in the rest of the book. We will introduce the linear models of travelling strings, panels, and plates. It will be assumed that the material is thin, i.e. its planar dimensions are much larger than its thickness. We will work in the small displacement regime, that is, with linear models approximating the behaviour of the system near the trivial equilibrium. As is well known in the theory of elasticity, this approximation allows for a decoupling of the in-plane and out-of-plane components in the dynamics of the system. We will concentrate on small out-of-…
Asymptotic observer of the link states of flexible joint robots with motor-side sensing
2015
This paper proposes an approach for observing the link states, i.e. angular position and velocity, of the robotic joints with elasticities, when only the motor-side sensing is available. By separating the state-dependent nonlinearities of the rigid manipulator dynamics a linear sub-model of the elastic joint robot is obtained in an observable state-space form. The standard asymptotic Luenberger state observer is then designed for the given motor position signal which is measured by encoder and rectified from the nonlinear contribution. The configurable poles of observer allow shaping the estimated states dynamics to be fast enough in relation to the actual resonant joint behavior. Therefore…
Direct evaluation of the equivalent linear damping for TLCD systems in random vibration for pre-design purposes
2014
Abstract Passive control of structural vibrations has received in recent years a great attention from researchers concerned with vibration control. Several types of devices have been proposed in order to reduce the dynamic responses of different kinds of structural systems. Among them, the Tuned Liquid Column Damper (TLCD) proved to be very effective in reducing vibration of structures. Since the increasing use of TLCDs in practical realizations, this paper aims at developing an approximate formulation, by means of a statistical linearization technique, able to estimate the parameters of a structure equipped with a TLCD subjected to random loads for pre-design purposes. Moreover, it is show…
A coupled cluster study of the 1 1A1g and 1 1B2u states of benzene
1998
A theoretical investigation of the equilibrium structures and harmonic frequencies of the 1 1A1g and 1 1B2u states of benzene is presented. The performance of coupled cluster singles (CCS), the recently proposed CC2 model, and coupled cluster singles and doubles (CCSD) is compared. The CC2 ground and excited states frequencies are a significant improvement of the CCS results and are relatively close to the CCSD results. A comparative analysis of the vibrations in the two electronic states of both C6H6 and C6D6 is presented. The reliability of predicted shifts in harmonic frequencies between the two states and isotopic shifts is estimated on the basis of the convergence in the CCS, CC2, and …
Resonance phenomena in a nonlinear neuronal circuit
2015
International audience; We characterizes a nonlinear circuit driven by a bichromatic excitation,that is the sum of two sinusoidal waves with different frequencies f1 and f2 suchthat f2 > f1. Our experiments are confirmed by a numerical analysis of the systemresponse obtained by solving numerically the differential equations which rule thecircuit voltages. Especially, we highlight that the response of the system at the lowfrequency can be optimized by the amplitude of the high frequency. By revisiting thiswell known vibrational resonance effect in the whole amplitude frequency parametricplane, we show experimentally and numerically that a much better resonance can beachieved when the two fre…
Vibrational Resonance in inhomogeneous and space-dependent nonlinear damped systems
2020
International audience; The properties of nonlinear systems have attracted a considerable interest these past years since they can be used to develop bio-inspired applications ranging from signal detection to image processing. Among these nonlinear signatures is Vibrational Resonance (V.R.) which expresses the ability of a nonlinear system to take benefit of a high frequency perturbation in order to enhance its response to a weak low frequency excitation . Since its introduction in mechanical systems and electronic devices, this effect has been widely reported in various systems and for different applications. Indeed, V.R can be used to detect subthreshold signals or to enhance the percepti…