scholarly journals Nonlinear Response Characteristics of Electrostrictive Material Sensors

2019 ◽  
Vol 31 (5) ◽  
pp. 1769
Author(s):  
Qian-Peng Li ◽  
Jia Xu ◽  
Guo-Song Feng ◽  
Zhi-Wen Zhu
Keyword(s):  
Nonlinear Response ◽  
Response Characteristics ◽  
Electrostrictive Material

Shooting With Deflation Algorithm-Based Nonlinear Response and Neimark-Sacker Bifurcation and Chaos in Floating Ring Bearing Systems

2016 ◽  
Vol 12 (3) ◽  
Author(s):  
Sitae Kim ◽  
Alan B. Palazzolo
Keyword(s):  
Nonlinear Response ◽  
Nonlinear Behavior ◽  
Rotor System ◽  
Operating Conditions ◽  
Fluid Film ◽  
Stable Limit ◽  
Bifurcation And Chaos ◽  
Chaotic Motions ◽  
Response Characteristics ◽  
Computation Efficiency

The double-sided fluid film force on the inner and outer ring surfaces of a floating ring bearing (FRB) creates strong nonlinear response characteristics such as coexistence of multiple orbits, Hopf bifurcation, Neimark-Sacker (N-S) bifurcation, and chaos in operations. An improved autonomous shooting with deflation algorithm is applied to a rigid rotor supported by FRBs for numerically analyzing its nonlinear behavior. The method enhances computation efficiency by avoiding previously found solutions in the numerical-based search. The solution manifold for phase state and period is obtained using arc-length continuation. It was determined that the FRB-rotor system has multiple response states near Hopf and N-S bifurcation points, and the bifurcation scenario depends on the ratio of floating ring length and diameter (L/D). Since multiple responses coexist under the same operating conditions, simulation of jumps between two stable limit cycles from potential disturbance such as sudden base excitation is demonstrated. In addition, this paper investigates chaotic motions in the FRB-rotor system, utilizing four different approaches, strange attractor, Lyapunov exponent, frequency spectrum, and bifurcation diagram. A numerical case study for quenching the large amplitude motion by adding unbalance force is provided and the result shows synchronization, i.e., subsynchronous frequency components are suppressed. In this research, the fluid film forces on the FRB are determined by applying the finite element method while prior work has utilized a short bearing approximation. Simulation response comparisons between the short bearing and finite bearing models are discussed.

Theoretical and Experimental Analysis of Nonlinear Dynamics in a Linear Compressor

2001 ◽  
Vol 124 (1) ◽  
pp. 152-154 ◽  
Author(s):  
Gyu-Sang Choe ◽  
Kwang-Joon Kim
Keyword(s):  
Steady State ◽  
Nonlinear Response ◽  
Dynamic Models ◽  
Steady State Response ◽  
Describing Function ◽  
Linear Compressor ◽  
Response Characteristics ◽  
State Response ◽  
Jump Phenomena ◽  
Method Effects

Steady-state nonlinear response characteristics of a linear compressor are investigated theoretically and experimentally. In the theoretical approach, motions of not only piston but also cylinder are considered and dynamic models for steady-state response predictions are formulated by applying the describing function method. Effects of piston mass on the jump phenomena are predicted by the derived models as an example of design parameter variation and compared with actual experimental results.

scholarly journals Nonlinear response characteristics of neural networks and single neurons undergoing optogenetic excitation

2020 ◽  
Vol 4 (3) ◽  
pp. 852-870
Author(s):  
Jannik Luboeinski ◽  
Tatjana Tchumatchenko
Keyword(s):  
Neural Networks ◽  
Nonlinear Response ◽  
Pulse Frequency ◽  
Simulation Code ◽  
Response Characteristics ◽  
Optogenetic Stimulation ◽  
Spatial Response ◽  
Temporal And Spatial ◽  
Light Beams ◽  
Indirect Stimulation

Optogenetic stimulation has become the method of choice for investigating neural computation in populations of neurons. Optogenetic experiments often aim to elicit a network response by stimulating specific groups of neurons. However, this is complicated by the fact that optogenetic stimulation is nonlinear, more light does not always equal to more spikes, and neurons that are not directly but indirectly stimulated could have a major impact on how networks respond to optogenetic stimulation. To clarify how optogenetic excitation of some neurons alters the network dynamics, we studied the temporal and spatial response of individual neurons and recurrent neural networks. In individual neurons, we find that neurons show a monotonic, saturating rate response to increasing light intensity and a nonmonotonic rate response to increasing pulse frequency. At the network level, we find that Gaussian light beams elicit spatial firing rate responses that are substantially broader than the stimulus profile. In summary, our analysis and our network simulation code allow us to predict the outcome of an optogenetic experiment and to assess whether the observed effects can be attributed to direct or indirect stimulation of neurons.

Nonlinear Response Characteristics of a Cracked Rotor in Maneuvering Aircraft

2003 ◽  
Author(s):  
Fu-Sheng Lin ◽  
Guang Meng ◽  
Eric Hahn
Keyword(s):  
Fault Diagnosis ◽  
Constant Velocity ◽  
Nonlinear Response ◽  
Nonlinear Behavior ◽  
Rotor System ◽  
Parameter Range ◽  
Cracked Rotor ◽  
Periodic Response ◽  
Response Characteristics ◽  
Cracked Rotor System

This paper investigates numerically the nonlinear response of a simple cracked rotor in moving supports, as may occur in aircraft rotors when the aircraft is maneuvering with constant velocity or acceleration. Of particular interest is the influence of the aircraft climb angle. Results show that the climb angle can markedly affect the parameter range for which the system is stable; and over which there results bifurcation, quasi-periodic response or chaotic response. It is shown that aircraft acceleration can also significantly affect the nonlinear behavior of the cracked rotor system, illustrating the possibility for online rotor crack fault diagnosis.

scholarly journals Nonlinear tuning of microresonators for dynamic range enhancement

2015 ◽  
Vol 471 (2179) ◽  
pp. 20140969 ◽  
Author(s):  
M. Saghafi ◽  
H. Dankowicz ◽  
W. Lacarbonara
Keyword(s):  
Nonlinear Response ◽  
Dynamic Range ◽  
Multiple Scales ◽  
Method Of Multiple Scales ◽  
Equations Of Motion ◽  
Path Following ◽  
Critical Amplitude ◽  
Inertia Effects ◽  
Response Characteristics ◽  
The Galerkin Method

This paper investigates the development of a novel framework and its implementation for the nonlinear tuning of nano/microresonators. Using geometrically exact mechanical formulations, a nonlinear model is obtained that governs the transverse and longitudinal dynamics of multilayer microbeams, and also takes into account rotary inertia effects. The partial differential equations of motion are discretized, according to the Galerkin method, after being reformulated into a mixed form. A zeroth-order shift as well as a hardening effect are observed in the frequency response of the beam. These results are confirmed by a higher order perturbation analysis using the method of multiple scales. An inverse problem is then proposed for the continuation of the critical amplitude at which the transition to nonlinear response characteristics occurs. Path-following techniques are employed to explore the dependence on the system parameters, as well as on the geometry of bilayer microbeams, of the magnitude of the dynamic range in nano/microresonators.

Nonlinear Response Characteristics of Discus Data Buoy Hull

2008 ◽  
Author(s):  
R. Balaji ◽  
S. A. Sannasiraj ◽  
V. Sundar
Keyword(s):  
Experimental Investigation ◽  
Response Time ◽  
Nonlinear Wave ◽  
Nonlinear Response ◽  
Phase Portraits ◽  
Testing Conditions ◽  
Response Characteristics ◽  
Wave Elevation ◽  
Time Histories ◽  
Spectral Representations

The response characteristics of the discus hull shaped data buoy under the influence of nonlinear wave conditions was studied in an experimental investigation. The measured wave elevation and the buoy response time histories were analyzed by phase-portraits as well as through the spectral representations. The details of the model, instrumentation, testing conditions and the analysis are presented and discussed in this paper.

Nonlinear Features in the Dynamic Response of a Cracked Beam Under Harmonic Forcing

2005 ◽  
Author(s):  
Ugo Andreaus ◽  
Paolo Casini ◽  
Fabrizio Vestroni
Keyword(s):  
Nonlinear Response ◽  
Damage Identification ◽  
Period Doubling ◽  
Element Model ◽  
Breathing Crack ◽  
Cracked Beam ◽  
Response Characteristics ◽  
Harmonic Forcing ◽  
Dimensional Finite Element ◽  
Nonlinear Features

Detection of damage in beam structures is usually pursued by means of methods based on the measured variations of modal quantities, like frequencies and eigenmodes. The drawback of these methods is the small sensitivity of modal quantities to concentrated damage. Since a crack introduces nonlinearities in the system, the use of nonlinear techniques of damage detection merits to be investigated. With this aim the present paper is devoted to analyze the peculiar features of the nonlinear response of a cracked beam. The problem of a cantilever beam with an asymmetric edge crack subjected to a harmonic forcing at the tip is considered as a plane problem and is solved by using two-dimensional finite element model; the behaviour of the breathing crack is simulated as a frictionless contact problem. The modification of the response with respect to the linear one is outlined: in particular, excitation of sub- and super-harmonics, period doubling, quasi-impulsive behaviour at crack interfaces are the main achievements. These response characteristics can be used in nonlinear techniques of damage identification.

Nonlinear Response of Stiffened Panel Suffered from Thermo-Acoustic Loadings

2014 ◽  
Vol 696 ◽  
pp. 17-22
Author(s):  
Yun Dong Sha ◽  
Huan Yu ◽  
Hao Yuan Wang
Keyword(s):  
Nonlinear Response ◽  
Stiffened Panel ◽  
Vibration Displacement ◽  
Stiffened Panels ◽  
Surface Protection ◽  
Response Characteristics ◽  
Combined Loads ◽  
Actual Use ◽  
Spectrum Density ◽  
Relationship Of

The surface protection systems of aerospace and aircraft are often constructed from discretely stiffened panels to support high thermal acoustic loadings. In actual use, the stiffened panels are often subject to compression, shear and combination of compression and shear loads, bucking instability is the most common failure mode. The analysis of the snap-through process of stiffened panel is always a challenge in the word. This paper studied mainly about the non-liner response of the steel stiffened-plates under combined loads of thermal and acoustic. Firstly, the nonlinear balance equation of bucking process is analysised and a improved arc-length method is introduced . Than the FEM numerical method is used to analysis the nonlinear response of a simply supported stiffened panel under different thermal acoustic loadings. The modal frequency and the vibration displacement and stress are calculated. The displacement power spectrum density is analyzed emphatically. Base on the calculated resulted results, the relationship of the fundamental response frequencies versus temperatures is analyzed comparatively, furthermore, the bucking and snap through response characteristics are discussed as well.

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