Experimental Characterization of Friction in a Negative Stiffness Nonlinear Oscillator

Nonlinear dissipative phenomena are common features of many dynamical systems and engineering applications, and their experimental characterization has always been a challenge among the research community. Within the wide range of nonlinear damping mechanisms, friction is surely one of the most common, and with a high impact on the dynamical behavior of structures. In this paper, the nonlinear identification of friction in a negative stiffness oscillator is pursued. The structure exhibits a strong nonlinear behavior, mainly due to its polynomial elastic restoring force with a negative stiffness region. This leads to an asymmetric double-well potential with two stable equilibrium positions, and the possibility of switching between them in a chaotic way. Friction plays a crucial role in this context, as it derives from the continuous sliding between the central guide and the moving mass. The system is driven through harmonic tests with several input amplitudes, in order to estimate the variations in the energy dissipated per cycle. The identification of the frictional behavior is then pursed by minimizing the errors between the experimental measurements and the model predictions, using the harmonic balance method in conjunction with a continuation technique on the forcing amplitudes.

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New Approaches of Nanocomposite Materials for Electromagnetic Sensors and Robotics

Advanced Instrument Engineering ◽

10.4018/978-1-4666-4165-5.ch005 ◽

2013 ◽

pp. 57-73

Author(s):

Alessandro Massaro ◽

Fabrizio Spano ◽

Diego Caratelli ◽

Alexander Yarovoy ◽

Roberto Cingolani ◽

...

Keyword(s):

Nanocomposite Materials ◽

Experimental Characterization ◽

Electromagnetic Sensors ◽

Nano Scale ◽

Wide Range ◽

Novel Devices ◽

And Robotics ◽

Numerical Approaches ◽

Nano Antennas

In this paper, the authors define new classes of devices based on nanocomposite materials (NMs). The work introduces approaches about the design and the experimental characterization of these materials. A wide range of applications is presented by discussing novel devices implemented by nanocomposite techniques including sensing and robotic in micro/nano scale. The approaches are oriented on the electromagnetic (EM) characterization of tailored devices such as sensors, and micro/nano antennas. New EM numerical approaches for the design are presented.

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Effect of Negative Stiffness Content on the Periodic Motion of Nonlinearly Coupled Oscillators

Journal of Computational and Nonlinear Dynamics ◽

10.1115/1.4052287 ◽

2021 ◽

Vol 16 (11) ◽

Author(s):

Mohammad A. Al-Shudeifat

Keyword(s):

Coupled Oscillators ◽

Dynamical Behavior ◽

Negative Stiffness ◽

Nonlinear Frequency ◽

Nonlinear Stiffness ◽

Nonlinear Coupling ◽

Nonlinear Dynamical ◽

Wide Range ◽

Coupling Force ◽

Linear And Nonlinear

Abstract The linear and nonlinear stiffness coupling forces in dynamical oscillators are usually dominated by positive stiffness components. Therefore, plotting the resultant force in y-axis with respect to the change in displacement in x-axis results in an odd symmetry in the first and third quadrants of the xy-plane. However, the appearance of negative stiffness content in coupling elements between dynamical oscillators generates a force that can be dominated by an odd symmetry in the second and fourth quadrants. The underlying nonlinear dynamical behavior of systems employing this kind of force has not been well-studied in the literature. Accordingly, the considered system here is composed of two linear oscillators that are nonlinearly coupled by a force of which the negative stiffness content is dominant. Therefore, the underlying dynamical behavior of the considered system in physical and dimensionless forms is studied on the frequency-energy plots where many backbone curves of periodic solution have been obtained. It is found that within a wide range of nonlinear frequency levels, the nonlinear coupling force is dominated by a strong negative stiffness content at the obtained frequency-energy plots backbones.

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Refining the Method of Averaging for a More Accurate Analytical Approximation to the Behaviors of a Damped Pendulum

Volume 1: 24th Conference on Mechanical Vibration and Noise, Parts A and B ◽

10.1115/detc2012-70202 ◽

2012 ◽

Author(s):

Clark C. McGehee ◽

Si Mohamed Sah ◽

Brian P. Mann

Keyword(s):

Dynamical Systems ◽

Nonlinear Dynamical Systems ◽

Nonlinear Damping ◽

Analytical Approximation ◽

Method Of Averaging ◽

Restoring Force ◽

Nonlinear Dynamical ◽

Wide Range ◽

Approximation Errors ◽

Kbm Method

KBM averaging is a widely used technique in the analysis of nonlinear dynamical systems. The KBM method allows complex systems to be approximated as perturbations of simple harmonic oscillator. In many cases, such as in otherwise linear systems with various forms nonlinear damping, the KBM method performs exceptionally well, with error proportional to the size of the perturbations. However, when the largest perturbation in the system arises from nonlinearities in the restoring force, the KBM method falls short, and the interesting effects of other nonlinear terms are drowned out by the approximation errors generated by the KBM method. By generalizing the notion of KBM averaging and approximating systems as perturbations the isoenergy contours of their corresponding Hamiltonian, a greater degree of accuracy can be obtained. We extend the work of several authors to show that not only is this method more accurate, but it is also simple to implement and generalizable to a wide range of nonlinear systems. As an illustrative example, the motion of a pendulum on a tilted platform is studied.

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Design and Characteristics Analysis of a Nonlinear Isolator Using a Curved-Mount-Spring-Roller Mechanism as Negative Stiffness Element

Mathematical Problems in Engineering ◽

10.1155/2018/1359461 ◽

2018 ◽

Vol 2018 ◽

pp. 1-15 ◽

Cited By ~ 2

Author(s):

Han Junshu ◽

Meng Lingshuai ◽

Sun Jinggong

Keyword(s):

Damping Ratio ◽

Harmonic Balance Method ◽

Excitation Amplitude ◽

Negative Stiffness ◽

Response Curves ◽

Restoring Force ◽

Characteristics Analysis ◽

Stiffness Softening ◽

Isolation Performance ◽

Cubic Stiffness

The characteristics of a passive nonlinear isolator are developed by combining a curved-mount-spring-roller mechanism as a negative stiffness corrector in parallel with a vertical linear spring. The static characteristics of the isolator are presented, and the configurative parameters are optimized to achieve a wider displacement range at the equilibrium position where the isolator has a low stiffness and the stiffness changes slightly. The restoring force of the isolator is approximated using a Taylor expansion to a cubic stiffness. Considering the overload and underload conditions, a dynamic equation is established as a Helmholtz-Duffing equation, and the resonance response of the nonlinear system is determined by employing the harmonic balance method (HBM). The frequency response curves (FRCs) are obtained for displacement excitations. The absolute displacement and acceleration transmissibility are defined and investigated to evaluate the performance of the nonlinear isolator, and they are compared with an equivalent linear isolator that can support the same mass with the same static deflection as the proposed isolator. The effects of the amplitude of the excitation, the offset displacement, and the damping ratio on the dynamic characteristics and the transmissibility performance are considered, and experiments are carried out to verify the above analysis. The results show that the overload and underload system can outperform the counterparts with the linear stiffness, softening stiffness, softening-hardening stiffness, and hardening stiffness with the magnitude of the excitation amplitude, and that its isolation performance is generally better than that of a linear system. The transmissibility, response, and resonance frequency of the system are affected by the excitation amplitude, offset displacement, cubic stiffness, and damping ratio. To obtain a better isolation performance, an appropriate mass, not-too-large amplitude, and larger damper are necessary for the proposed isolator.

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Experimental Characterization of Nonlinear Damping in the F-16 Wing Structure

Journal of Aircraft ◽

10.2514/1.c035850 ◽

2020 ◽

pp. 1-8

Author(s):

Charles M. Denegri ◽

Vinod K. Sharma ◽

Lynn J. Neergaard

Keyword(s):

Nonlinear Damping ◽

Experimental Characterization ◽

Wing Structure

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Silicon-Based Multilayer Waveguides for Integrated Photonic Devices from the Near to Mid Infrared

Applied Sciences ◽

10.3390/app11031227 ◽

2021 ◽

Vol 11 (3) ◽

pp. 1227

Author(s):

Iñaki López García ◽

Mario Siciliani de Cumis ◽

Davide Mazzotti ◽

Iacopo Galli ◽

Pablo Cancio Pastor ◽

...

Keyword(s):

Photonic Devices ◽

Visible Range ◽

Experimental Characterization ◽

Mid Infrared ◽

Wide Range ◽

Infrared Spectral ◽

Silicon Based ◽

Optical Behavior ◽

532 Nm

Advancements in spectroscopy, quantum optics, communication, and sensing require new classes of integrated photonic devices to host a wide range of non-linear optical processes involving wavelengths from the visible to the infrared. In this framework, waveguide (WG) structures designed with innovative geometry and materials can play a key role. We report both finite element modeling and experimental characterization of silicon nitride multilayer WGs from the visible to the mid-infrared spectral regions. The simulations evaluated optical behavior and mechanical stress as a function of number of WG layers and photonic structure dimensions. WGs were optimized for waveguiding at 1550 nm and 2640 nm. Experimental characterization focused on optical behavior and coupling losses from 532 nm to 2640 nm. Measured losses in WGs indicate a quasi-perfect waveguiding behavior in the IR range (with losses below 6 dB), with a relevant increase (up to 20 dB) in the visible range.

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Experimental Characterization of Contact Hysteresis at High Temperatures

Volume 5: Marine; Microturbines and Small Turbomachinery; Oil and Gas Applications; Structures and Dynamics, Parts A and B ◽

10.1115/gt2006-90757 ◽

2006 ◽

Cited By ~ 8

Author(s):

Sergio Filippi ◽

Esequiel B. Rodrigues ◽

Muzio M. Gola

Keyword(s):

Friction Coefficient ◽

Experimental Determination ◽

Measurement System ◽

Experimental Characterization ◽

Test Rig ◽

Tangential Load ◽

Wide Range ◽

Induction System

The current paper presents a measurement system for the experimental determination of contact hysteresis cycles at temperatures up to 800° C. A test rig was designed to conduct experiments in a wide range of temperatures, with different combinations of normal and tangential load, frequencies and contacting materials. An induction system supplies the heat for measurements of hysteresis cycles at the required temperatures. Measurements show the dependence of the friction coefficient on temperature.

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Design and experiments of a quasi–zero-stiffness isolator with a noncircular cam-based negative-stiffness mechanism

Journal of Vibration and Control ◽

10.1177/1077546320908689 ◽

2020 ◽

Vol 26 (21-22) ◽

pp. 1935-1947

Author(s):

Ming Li ◽

Wei Cheng ◽

Ruili Xie

Keyword(s):

Harmonic Balance ◽

Experimental Studies ◽

Approximation Error ◽

Low Frequency ◽

Harmonic Balance Method ◽

Negative Stiffness ◽

Restoring Force ◽

Stiffness Characteristic ◽

Physical Prototype ◽

Negative Stiffness Mechanism

This article presents a quasi–zero-stiffness isolator with a cam-based negative-stiffness mechanism, where the cam has a user-defined noncircular profile to generate negative stiffness to counterbalance the positive stiffness of the vertical spring and yield the quasi–zero-stiffness characteristic around the equilibrium position. Unlike previous studies, the proposed quasi–zero-stiffness isolator has the preferable feature that the desired cubic restoring force can be directly obtained through the well-designed profile of the cam in the negative-stiffness mechanism with the friction considered during the model design, rather than through the Taylor expansion and friction-ignoring assumption, which can avoid the approximation error between the theoretical design and the specific realization. The pure-cubic nonlinear differential equation of motion of the quasi–zero-stiffness isolator is derived and solved with the harmonic balance method, followed by the discussion of the relevant dynamic characteristics. Experimental studies are carried out based on the physical prototype of the quasi–zero-stiffness isolator. The results show that the quasi–zero-stiffness isolator can greatly extend the isolation frequency bandwidth and has a much lower resonance peak. In the low-frequency band, the quasi–zero-stiffness isolator greatly outperforms the corresponding linear system but is equivalent or even inferior in the high-frequency range with the increase of excitation force.

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