Sensitivity Analysis of Frequency Response Functions for Load Resistance of Piezoelectric Energy Harvesters

2018 ◽  
pp. 136-148
Author(s):  
Rabie Aloui ◽  
Walid Larbi ◽  
Mnaouar Chouchane
Keyword(s):  
Sensitivity Analysis ◽  
Frequency Response ◽  
Load Resistance ◽  
Response Functions ◽  
Frequency Response Functions ◽  
Energy Harvesters ◽  
Piezoelectric Energy

System Identification of Nonlinear Mechanical Systems Using Embedded Sensitivity Functions

2005 ◽  
Vol 127 (6) ◽  
pp. 530-541 ◽  
Author(s):  
Chulho Yang ◽  
Douglas E. Adams ◽  
Sam Ciray
Keyword(s):  
Sensitivity Analysis ◽  
System Identification ◽  
Frequency Response ◽  
Mechanical Systems ◽  
Rate Of Change ◽  
Response Functions ◽  
Vehicle Exhaust ◽  
Nonlinear Parameters ◽  
Frequency Response Functions ◽  
Sensitivity Functions

A novel method of experimental sensitivity analysis for nonlinear system identification of mechanical systems is examined here. It has been shown previously that embedded sensitivity functions, which are quadratic algebraic products of frequency response function data, can be used to identify structural design modifications for reducing vibration levels. It is shown here that embedded sensitivity functions can also be used to characterize and identify mechanical nonlinearities. Embedded sensitivity functions represent the rate of change of the response with variation in input amplitude, and yield estimates of system parameters without being explicitly dependent on them. Frequency response functions are measured at multiple input amplitudes and combined using embedded sensitivity analysis to extract spectral patterns for characterizing systems with stiffness and damping nonlinearities. By comparing embedded sensitivity functions with finite difference frequency response sensitivities, which incorporate the amplitude-dependent behavior of mechanical nonlinearities, models can be determined using an inverse problem that uses system sensitivity to estimate parameters. Expressions for estimating nonlinear parameters are derived using Taylor series expansions of frequency response functions in conjunction with the method of harmonic balance for periodic signals. Using both simulated and experimental data, this procedure is applied to estimate the nonlinear parameters of a two degree-of-freedom model and a vehicle exhaust system to verify the approach.

scholarly journals Sensitivity Analysis of Viscoelastic Structures

2006 ◽  
Vol 13 (4-5) ◽  
pp. 545-558 ◽  
Author(s):  
A.M.G. de Lima ◽  
M.H. Stoppa ◽  
D.A. Rade ◽  
V. Steffen Jr.
Keyword(s):  
Sensitivity Analysis ◽  
Frequency Response ◽  
Numerical Models ◽  
Complex Frequency ◽  
Response Functions ◽  
Viscoelastic Materials ◽  
Frequency Response Functions ◽  
Element Discretization ◽  
Analysis And Design ◽  
First Order

In the context of control of sound and vibration of mechanical systems, the use of viscoelastic materials has been regarded as a convenient strategy in many types of industrial applications. Numerical models based on finite element discretization have been frequently used in the analysis and design of complex structural systems incorporating viscoelastic materials. Such models must account for the typical dependence of the viscoelastic characteristics on operational and environmental parameters, such as frequency and temperature. In many applications, including optimal design and model updating, sensitivity analysis based on numerical models is a very usefull tool. In this paper, the formulation of first-order sensitivity analysis of complex frequency response functions is developed for plates treated with passive constraining damping layers, considering geometrical characteristics, such as the thicknesses of the multi-layer components, as design variables. Also, the sensitivity of the frequency response functions with respect to temperature is introduced. As an example, response derivatives are calculated for a three-layer sandwich plate and the results obtained are compared with first-order finite-difference approximations.

scholarly journals Load Resistance Optimization of a Broadband Bistable Piezoelectric Energy Harvester for Primary Harmonic and Subharmonic Behaviors

2021 ◽  
Vol 13 (5) ◽  
pp. 2865 ◽  
Author(s):  
Sungryong Bae ◽  
Pilkee Kim
Keyword(s):  
Energy Harvester ◽  
Load Resistance ◽  
Oscillation Period ◽  
Ambient Vibration ◽  
Ambient Vibrations ◽  
Frequency Dependency ◽  
Energy Harvesters ◽  
Piezoelectric Energy ◽  
Optimal Load ◽  
Bistable Energy Harvester

In this study, optimization of the external load resistance of a piezoelectric bistable energy harvester was performed for primary harmonic (period-1T) and subharmonic (period-3T) interwell motions. The analytical expression of the optimal load resistance was derived, based on the spectral analyses of the interwell motions, and evaluated. The analytical results are in excellent agreement with the numerical ones. A parametric study shows that the optimal load resistance depended on the forcing frequency, but not the intensity of the ambient vibration. Additionally, it was found that the optimal resistance for the period-3T interwell motion tended to be approximately three times larger than that for the period-1T interwell motion, which means that the optimal resistance was directly affected by the oscillation frequency (or oscillation period) of the motion rather than the forcing frequency. For broadband energy harvesting applications, the subharmonic interwell motion is also useful, in addition to the primary harmonic interwell motion. In designing such piezoelectric bistable energy harvesters, the frequency dependency of the optimal load resistance should be considered properly depending on ambient vibrations.

scholarly journals Identification of relevant acoustic transfer paths for WT drivetrains with an operational transfer path analysis

2021 ◽  
Author(s):  
W. Schünemann ◽  
R. Schelenz ◽  
G. Jacobs ◽  
W. Vocaet
Keyword(s):  
Path Analysis ◽  
Wind Turbine ◽  
Frequency Response ◽  
Mechanical System ◽  
Reference Point ◽  
Response Functions ◽  
Frequency Response Functions ◽  
Transfer Path ◽  
Transfer Path Analysis ◽  
Turbine Model

AbstractThe aim of a transfer path analysis (TPA) is to view the transmission of vibrations in a mechanical system from the point of excitation over interface points to a reference point. For that matter, the Frequency Response Functions (FRF) of a system or the Transmissibility Matrix is determined and examined in conjunction with the interface forces at the transfer path. This paper will cover the application of an operational TPA for a wind turbine model. In doing so the path contribution of relevant transfer paths are made visible and can be optimized individually.

Calculation of Component Mode Synthesis Matrices From Measured Frequency Response Functions, Part 2: Application

1998 ◽  
Vol 120 (2) ◽  
pp. 509-516 ◽  
Author(s):  
J. A. Morgan ◽  
C. Pierre ◽  
G. M. Hulbert
Keyword(s):  
Frequency Response ◽  
Coupled System ◽  
Companion Paper ◽  
Component Mode Synthesis ◽  
Response Functions ◽  
Frequency Response Functions ◽  
Measured Frequency ◽  
Measured Frequency Response ◽  
Coupled Beams ◽  
The Individual

This paper demonstrates how to calculate Craig-Bampton component mode synthesis matrices from measured frequency response functions. The procedure is based on a modified residual flexibility method, from which the Craig-Bampton CMS matrices are recovered, as presented in the companion paper, Part I (Morgan et al., 1998). A system of two coupled beams is analyzed using the experimentally-based method. The individual beams’ CMS matrices are calculated from measured frequency response functions. Then, the two beams are analytically coupled together using the test-derived matrices. Good agreement is obtained between the coupled system and the measured results.

Experimental Study for Extraction of Normal Modes

1995 ◽  
Author(s):  
S. Y. Chen ◽  
M. S. Ju ◽  
Y. G. Tsuei
Keyword(s):  
Frequency Response ◽  
Normal Mode ◽  
Normal Modes ◽  
Measurement Data ◽  
Mode Shapes ◽  
Complex Frequency ◽  
Response Functions ◽  
Frequency Response Functions ◽  
Incomplete System ◽  
Coupled Structures

Abstract A frequency-domain technique to extract the normal mode from the measurement data for highly coupled structures is developed. The relation between the complex frequency response functions and the normal frequency response functions is derived. An algorithm is developed to calculate the normal modes from the complex frequency response functions. In this algorithm, only the magnitude and phase data at the undamped natural frequencies are utilized to extract the normal mode shapes. In addition, the developed technique is independent of the damping types. It is only dependent on the model of analysis. Two experimental examples are employed to illustrate the applicability of the technique. The effects due to different measurement locations are addressed. The results indicate that this technique can successfully extract the normal modes from the noisy frequency response functions of a highly coupled incomplete system.

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