Analytical Study of a Piezoelectric Frequency Up-Conversion Harvester Under Sawtooth Wave Excitation

2018 ◽  
Author(s):  
Saeed Onsorynezhad ◽  
Amin Abedini ◽  
Fengxia Wang
Keyword(s):  
Numerical Solutions ◽  
Excitation Frequency ◽  
Dynamics Analysis ◽  
Periodic Motions ◽  
Lumped Model ◽  
Sawtooth Wave ◽  
Piezoelectric Beam ◽  
Period 2 ◽  
Mass Spring ◽  
The Impact

In this work, an impact based frequency up-conversion mechanism is studied via discontinuous dynamics analysis. The mechanism consists of a moving stopper and a piezoelectric beam. The repeated free vibration of the piezoelectric beam achieved through the impaction between the stopper and the beam, With the stopper excited by a sawtooth wave. Due to the impact, the system contains complex discontinuous dynamics, hence to better understand the energy harvesting performance of the piezoelectric beam, we seek the simple periodic motions of the system. As the system parameter varies, the output voltage and power of the piezoelectric beam with periodic motions is obtained. These results were also compared with those obtained when the piezoelectric beam is directly subjected to the same sawtooth wave. The piezoelectric beam was modeled as a mass-spring-damper system, and the linear piezoelectric constitutive equations have been used to obtain the lumped model of the piezoelectric beam. In this study, numerical solutions of the generated power and voltage were obtained via discontinuous dynamics analysis. When the excitation frequency is low, the effect of frequency-up-conversion is demonstrated by comparing the generated power of two cases: piezoelectric beam excited via impact and beam directly subject to the sawtooth wave. The stable and unstable periodic motions and bifurcation trees of the impact parameters are predicted analytically versus varying excitation frequency for period-1 and period-2.

Discontinuous Dynamics of a Frequency Up-Conversion Piezoelectric Harvester

2019 ◽  
Author(s):  
Saeed Onsorynezhad ◽  
Fengxia Wang
Keyword(s):  
Energy Harvesting ◽  
Complex Dynamics ◽  
Excitation Frequency ◽  
Dynamics Analysis ◽  
Piezoelectric Bimorph ◽  
Periodic Motions ◽  
Piezoelectric Energy ◽  
Piezoelectric Beam ◽  
Period 2 ◽  
Euler Bernoulli Beam

Abstract This study investigates an impact based frequency up-conversion mechanism via discontinuous dynamics analysis. The mechanism composed of a stopper and a piezoelectric bimorph. The piezoelectric beam is subjected to a sinusoidal base excitation and impacts with the stopper. In this system, complex dynamics are induced by impacts, hence to better understand the energy harvesting performance of the piezoelectric beam, we seek the steady state periodic motions of the system. As the excitation frequency varies, the output voltage and power of the piezoelectric beam with periodic motions were obtained. The piezoelectric bimorph was modeled as an Euler-Bernoulli beam, and the linear piezoelectric constitutive equations were used to obtain the equations of the piezoelectric beam. The generated voltage and power were obtained using discontinuous dynamics analysis. In order to better analyze the energy harvesting performance of the piezoelectric energy harvester, the stable and unstable periodic motions were obtained. The bifurcation diagram of the period-1 and period-2 motions were obtained analytically as the excitation frequency varying.

scholarly journals Parametric optimization of a frequency-up-conversion piezoelectric harvester via discontinuous analysis

2020 ◽  
Vol 26 (15-16) ◽  
pp. 1241-1252 ◽  
Author(s):  
Saeed Onsorynezhad ◽  
Amin Abedini ◽  
Fengxia Wang
Keyword(s):  
Energy Harvester ◽  
High Efficiency ◽  
Excitation Frequency ◽  
Constitutive Law ◽  
Critical Parameters ◽  
Piezoelectric Bimorph ◽  
Piezoelectric Beam ◽  
Period 2 ◽  
Euler Bernoulli Beam ◽  
Piezoelectric Harvester

In this study, the dynamical and electrical behaviors of an impact-based frequency-up-conversion energy harvester were studied based on discontinuous dynamics theory. This analytical study enables us to better understand the response of an impact-based frequency-up-conversion energy harvester as system parameters change, hence, guiding us to design a high-efficiency energy harvester via optimizing the values of the critical parameters of the system. For a given base excitation, the optimum gap to maximize the output power was obtained. The energy harvester consists of a sinusoidal vibrating piezoelectric bimorph and a stopper. The equations of the piezoelectric bimorph, which was modeled as an Euler–Bernoulli beam, were obtained based on the linear piezoelectric constitutive law. The generated voltage and power of the energy harvester were obtained via discontinuous dynamics analysis. Furthermore, the bifurcation diagrams of period-1 and period-2 motions were presented as the excitation frequency varying. To better understand the effect of different parameters on the performance of our system, the bifurcation trees of the period-1 motion versus varying excitation frequency were analytically obtained for different initial gap distances between the piezoelectric beam and the stopper. In addition, the bifurcation diagram of period solutions with a constant excitation frequency and varying gap distance was also attained.

Period-1 Motions to Chaos With Varying Excitation Frequency in a Parametrically Driven Pendulum

2019 ◽  
Author(s):  
Yu Guo ◽  
Albert C. J. Luo
Keyword(s):  
Differential Equations ◽  
Excitation Frequency ◽  
Analytical Prediction ◽  
Algebraic Equations ◽  
Periodic Motions ◽  
Discrete Maps ◽  
Period 2 ◽  
Mapping Structures ◽  
Nonlinear Algebraic Equations ◽  
Stability And Bifurcations

Abstract In this paper, with varying excitation frequency, period-1 motions to chaos in a parametrically driven pendulum are presented through period-1 to period-4 motions. Using the implicit discrete maps of the corresponding differential equations, discrete mapping structures are developed for different periodic motions, and the corresponding nonlinear algebraic equations of such mapping structures are solved for analytical predictions of bifurcation trees of periodic motions. Both period-1 static points to period-2 motions and period-1 motions to period-4 motions are illustrated. The corresponding stability and bifurcations are studied. Finally, numerical illustrations of various periodic motions on the bifurcation trees are presented in verification of the analytical prediction.

Instability and Collapse in Discrete Wave Equations

2005 ◽  
Vol 5 (3) ◽  
pp. 223-241
Author(s):  
A. Carpio ◽  
G. Duro
Keyword(s):  
Continuum Limit ◽  
Wave Equations ◽  
Numerical Solutions ◽  
Blow Up ◽  
Theoretical Predictions ◽  
Initial States ◽  
The Impact ◽  
The Continuum

AbstractUnstable growth phenomena in spatially discrete wave equations are studied. We characterize sets of initial states leading to instability and collapse and obtain analytical predictions for the blow-up time. The theoretical predictions are con- trasted with the numerical solutions computed by a variety of schemes. The behavior of the systems in the continuum limit and the impact of discreteness and friction are discussed.

scholarly journals Vibro-Acoustical Sensitivities of Stiffened Aircraft Structures Due to Attached Mass-Spring-Dampers with Uncertain Parameters

Aerospace ◽  
2021 ◽  
Vol 8 (7) ◽  
pp. 174
Author(s):  
Johannes Seidel ◽  
Stephan Lippert ◽  
Otto von Estorff
Keyword(s):  
System Response ◽  
Fuzzy Arithmetic ◽  
Parameter Uncertainties ◽  
Excitation Spectra ◽  
Radiated Noise ◽  
Linking Elements ◽  
Manufacturing Tolerances ◽  
Suitable Framework ◽  
Mass Spring ◽  
The Impact

The slightest manufacturing tolerances and variances of material properties can indeed have a significant impact on structural modes. An unintentional shift of eigenfrequencies towards dominant excitation frequencies may lead to increased vibration amplitudes of the structure resulting in radiated noise, e.g., reducing passenger comfort inside an aircraft’s cabin. This paper focuses on so-called non-structural masses of an aircraft, also known as the secondary structure that are attached to the primary structure via clips, brackets, and shock mounts and constitute a significant part of the overall mass of an aircraft’s structure. Using the example of a simplified fuselage panel, the vibro-acoustical consequences of parameter uncertainties in linking elements are studied. Here, the fuzzy arithmetic provides a suitable framework to describe uncertainties, create combination matrices, and evaluate the simulation results regarding target quantities and the impact of each parameter on the overall system response. To assess the vibrations of the fuzzy structure and by taking into account the excitation spectra of engine noise, modal and frequency response analyses are conducted.

Floating Roof Influence on Seismic Response of Large Vertical Storage Tank

2013 ◽  
Vol 671-674 ◽  
pp. 1399-1402
Author(s):  
Ying Sun ◽  
Jian Gang Sun ◽  
Li Fu Cui
Keyword(s):  
Seismic Response ◽  
Storage Tank ◽  
Numerical Solutions ◽  
Fluid Pressure ◽  
Seismic Intensity ◽  
Site Conditions ◽  
Storage Tanks ◽  
Analysis Model ◽  
Base Shear ◽  
The Impact

To study the impact of floating roof on seismic response of vertical storage tank structure system subjected to seismic excitation, select 150000m3 storage tanks as research object, and the finite element analysis model of storage tanks with and without floating roof were established respectively. The seismic response of these two types of structure in different site conditions and seismic intensity were calculated and the numerical solutions were compared. The results show that floating roof has little impact on base shear and base moment in different site conditions and seismic intensity. Floating roof can effectively reduce the sloshing wave height. The influence of floating roof on dynamic fluid pressure decreases with the increase of seismic intensity, which is less affected by ground conditions.

scholarly journals The impact of nasal adhesions on airflow and mucosal cooling - a computational fluid dynamics analysis

2021 ◽  
pp. 103719
Author(s):  
Praween Senanayake ◽  
Hana Salati ◽  
Eugene Wong ◽  
Kimberley Bradshaw ◽  
Yidan Shang ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Dynamics Analysis ◽  
Computational Fluid Dynamics Analysis ◽  
The Impact

scholarly journals The impact of the SARS-CoV-2 pandemic on referral characteristics in a national tertiary spinal injuries unit

2021 ◽  
Author(s):  
Louis O’Halloran ◽  
Daniel P. Ahern ◽  
Jake M. McDonnell ◽  
Gráinne M. Cunniffe ◽  
Michael K. Dodds ◽  
...  
Keyword(s):  
Road Traffic ◽  
Spinal Injury ◽  
Disc Disease ◽  
Tertiary Referral Centre ◽  
Period 2 ◽  
Spine Pathology ◽  
Social Restriction ◽  
Notable Increase ◽  
Almost All ◽  
The Impact

Abstract Background The SARS-CoV-2 pandemic has had profound implications on healthcare institutions. Aims This study aims to assess and compare referral patterns during COVID-19 to corresponding dates for the preceding 3 years (2017–2019), in order to preemptively coordinate the logistics of the surgical unit for similar future experiences. Methods Retrospective review for our institution, a national tertiary referral centre for spine pathology. Two distinct time-points were chosen to represent the varied levels of social restriction during the current pandemic: (i) study period 1 (SP1) from 11 November 2020 to 08 June 2020 represents a national lockdown, and (ii) study period 2 (SP2) from 09 June 2020 to 09 September 2020 indicates an easing of restrictions. Both periods were compared to corresponding dates (CP1: 11 March–08 June and CP2 09 June–09 September) for the preceding 3 years (2017–2019). Data collected included age, gender, and mechanism of injury (MOI) for descriptive analyses. MOIs were categorised into disc disease, cyclist, road-traffic-accident (RTA), falls < 2 m, falls > 2 m, malignancy, sporting injuries, and miscellaneous. Results All MOI categories witnessed a reduction in referral numbers during SP1: disc disease (−29%), cyclist (−5%), RTAs (−66%), falls < 2 m (−39%), falls > 2 m (−17%), malignancy (−33%), sporting injuries (−100%), and miscellaneous (−58%). Four of 8 categories (RTAs, falls < 2 m, malignancy, miscellaneous) showed a trend towards return of pre-lockdown values during SP2. Two categories (disc disease, falls > 2 m) showed a further reduction (−34%, −27%) during SP2. One category (sporting injuries) portrayed a complete return to normal values during SP2 while a notable increase in cyclist-related referrals was witnessed (+ 63%) when compared with corresponding dates of previous years. Conclusion Spinal injury continues to occur across almost all categories, albeit at considerably reduced numbers. RTAs and falls remained the most common MOI. Awareness needs to be drawn to the reduction of malignancy-related referrals to dissuade people with such symptoms from avoiding presentation to hospital over periods of social restrictions.

Analytical and Experimental Simulation of Loose Pedestal Dynamic Effects on a Rotating Machine Vibrational Response

1991 ◽  
Author(s):  
Pavel Goldman ◽  
Agnes Muszynska
Keyword(s):  
Excitation Frequency ◽  
Experimental Studies ◽  
Experimental Simulation ◽  
Physical Parameters ◽  
Vibrational Response ◽  
Rotating Machine ◽  
Qualitative Pattern ◽  
The Impact ◽  
Good Agreement ◽  
Periodic Changes

Abstract This report presents experimental, analytical, and numerical results describing vibrational phenomena in a rotating machine with one loose pedestal. The loose-pedestal machine rotor vibrations represent unbalance-related excited vibrations of synchronous and fractional subsynchronous regimes. In this study the loose-pedestal machine is first simulated by a simple vibrating beam excited by a shaker mounted on it. The shaker simulates an unbalanced machine rotor. The beam occasionally enters in contact with the foundation. The excited vibrations are modified by impacting occurrences, and by periodic changes in system stiffness. A new model of the impact has been developed. The results of analytical and experimental studies stand in a good agreement. They illustrate the existence of the synchronous regime and several subsynchronous fractional regimes in various excitation frequency ranges. The analysis adequately predicts the occurrence of these regimes and determines the physical parameters affecting them. The analytical and experimental results are then compared with the responses of experimental rotor rig with one bearing pedestal looseness. They show the same qualitative pattern.

Galloping Vibration of Nonlinear Cables Through a Two Degree-of-Freedom Oscillator

2016 ◽  
Author(s):  
Albert C. J. Luo ◽  
Bo Yu
Keyword(s):  
Transmission Line ◽  
Analytical Solutions ◽  
Transmission Lines ◽  
Nonlinear Oscillator ◽  
Numerical Solutions ◽  
Degree Of Freedom ◽  
Periodic Motions ◽  
Stability And Bifurcation ◽  
Two Degree Of Freedom

In this paper, galloping vibrations of a lightly iced transmission line are investigated through a two-degree-of-freedom (2-DOF) nonlinear oscillator. The 2-DOF nonlinear oscillator is used to describe the transverse and torsional motions of the galloping cables. The analytical solutions of periodic motions of galloping cables are presented through generalized harmonic balanced method. The analytical solutions of periodic motions for the galloping cable are compared with the numerical solutions, and the corresponding stability and bifurcation of periodic motions are analyzed by the eigenvalues analysis. To demonstrate the accuracy of the analytical solutions of periodic motions, the harmonic amplitudes are presented. This investigation will help one better understand galloping mechanism of iced transmission lines.

Sign in / Sign up

Export Citation Format

Share Document