---
_id: '9794'
abstract:
- lang: eng
  text: 'A piezoelectric cantilever beam with a tip mass at its free end is a common
    energy harvester configuration. This article introduces a new principle of designing
    such a harvester that increases the generated power without changing the resonance
    frequency of the harvester: the attraction force between two permanent magnets
    is used to add stiffness to the system. This magnetic stiffening counters the
    effect of the tip mass on the efficient operation frequency. Five set-ups incorporating
    piezoelectric bimorph cantilevers of the same type in different mechanical configurations
    are compared theoretically and experimentally to investigate the feasibility of
    this principle: theoretical and experimental results show that magnetically stiffened
    harvesters have important advantages over conventional set-ups with and without
    tip mass. They generate more power while only slightly increasing the deflection
    in the piezoelectric harvester and they can be tuned across a wide range of excitation
    frequencies.'
author:
- first_name: Waleed
  full_name: Al-Ashtari, Waleed
  last_name: Al-Ashtari
- first_name: Matthias
  full_name: Hunstig, Matthias
  last_name: Hunstig
- first_name: Tobias
  full_name: Hemsel, Tobias
  id: '210'
  last_name: Hemsel
- first_name: Walter
  full_name: Sextro, Walter
  id: '21220'
  last_name: Sextro
citation:
  ama: Al-Ashtari W, Hunstig M, Hemsel T, Sextro W. Increasing the power of piezoelectric
    energy harvesters by magnetic stiffening. <i>Journal of Intelligent Material Systems
    and Structures</i>. 2013;24(11):1332-1342. doi:<a href="https://doi.org/10.1177/1045389X13483021">10.1177/1045389X13483021</a>
  apa: Al-Ashtari, W., Hunstig, M., Hemsel, T., &#38; Sextro, W. (2013). Increasing
    the power of piezoelectric energy harvesters by magnetic stiffening. <i>Journal
    of Intelligent Material Systems and Structures</i>, <i>24</i>(11), 1332–1342.
    <a href="https://doi.org/10.1177/1045389X13483021">https://doi.org/10.1177/1045389X13483021</a>
  bibtex: '@article{Al-Ashtari_Hunstig_Hemsel_Sextro_2013, title={Increasing the power
    of piezoelectric energy harvesters by magnetic stiffening}, volume={24}, DOI={<a
    href="https://doi.org/10.1177/1045389X13483021">10.1177/1045389X13483021</a>},
    number={11}, journal={Journal of Intelligent Material Systems and Structures},
    author={Al-Ashtari, Waleed and Hunstig, Matthias and Hemsel, Tobias and Sextro,
    Walter}, year={2013}, pages={1332–1342} }'
  chicago: 'Al-Ashtari, Waleed, Matthias Hunstig, Tobias Hemsel, and Walter Sextro.
    “Increasing the Power of Piezoelectric Energy Harvesters by Magnetic Stiffening.”
    <i>Journal of Intelligent Material Systems and Structures</i> 24, no. 11 (2013):
    1332–42. <a href="https://doi.org/10.1177/1045389X13483021">https://doi.org/10.1177/1045389X13483021</a>.'
  ieee: W. Al-Ashtari, M. Hunstig, T. Hemsel, and W. Sextro, “Increasing the power
    of piezoelectric energy harvesters by magnetic stiffening,” <i>Journal of Intelligent
    Material Systems and Structures</i>, vol. 24, no. 11, pp. 1332–1342, 2013.
  mla: Al-Ashtari, Waleed, et al. “Increasing the Power of Piezoelectric Energy Harvesters
    by Magnetic Stiffening.” <i>Journal of Intelligent Material Systems and Structures</i>,
    vol. 24, no. 11, 2013, pp. 1332–42, doi:<a href="https://doi.org/10.1177/1045389X13483021">10.1177/1045389X13483021</a>.
  short: W. Al-Ashtari, M. Hunstig, T. Hemsel, W. Sextro, Journal of Intelligent Material
    Systems and Structures 24 (2013) 1332–1342.
date_created: 2019-05-13T13:51:00Z
date_updated: 2022-01-06T07:04:20Z
department:
- _id: '151'
doi: 10.1177/1045389X13483021
intvolume: '        24'
issue: '11'
language:
- iso: eng
page: 1332-1342
publication: Journal of Intelligent Material Systems and Structures
status: public
title: Increasing the power of piezoelectric energy harvesters by magnetic stiffening
type: journal_article
user_id: '55222'
volume: 24
year: '2013'
...
---
_id: '9795'
abstract:
- lang: eng
  text: Power and bandwidth of piezoelectric harvesters can be increased by using
    multiple piezoelectric elements in one harvester. In this contribution, a novel
    energy harvesting cantilever array with magnetic tuning including three piezoelectric
    bimorphs is investigated theoretically and experimentally, with a good agreement
    between model and experiment. Other than harvester designs proposed before, this
    array is easy to manufacture and insensitive to manufacturing tolerances because
    its optimum operation frequency can be re-adjusted after fabrication. Using the
    superposition principle, the Butterworth-Van Dyke model and a mechanical lumped
    parameters model, the generated voltage and current are determined analytically.
    Formulas for calculating the power generated by array harvesters with an arbitrary
    number of piezoelectric elements connected in series or in parallel are derived.
    It is shown that optimum harvester design must take both the connected load and
    the operating frequency into account. Strategies for connecting multiple bimorphs
    to increase the maximum generated power and/or enhance the bandwidth compared
    to a single bimorph harvester are investigated. For bandwidth enhancement it is
    essential that individual rectifiers are used for the bimorphs. An example with
    three bimorphs shows that, depending on the chosen tuning strategy, the power
    is increased by about 340\% or the bandwidth is increased by about 500\%, compared
    to one single bimorph.
author:
- first_name: Waleed
  full_name: Al-Ashtari, Waleed
  last_name: Al-Ashtari
- first_name: Matthias
  full_name: Hunstig, Matthias
  last_name: Hunstig
- first_name: Tobias
  full_name: Hemsel, Tobias
  id: '210'
  last_name: Hemsel
- first_name: Walter
  full_name: Sextro, Walter
  id: '21220'
  last_name: Sextro
citation:
  ama: 'Al-Ashtari W, Hunstig M, Hemsel T, Sextro W. Enhanced energy harvesting using
    multiple piezoelectric elements: Theory and experiments. <i>Sensors and Actuators
    A: Physical</i>. 2013;200:138-146. doi:<a href="https://doi.org/10.1016/j.sna.2013.01.008">10.1016/j.sna.2013.01.008</a>'
  apa: 'Al-Ashtari, W., Hunstig, M., Hemsel, T., &#38; Sextro, W. (2013). Enhanced
    energy harvesting using multiple piezoelectric elements: Theory and experiments.
    <i>Sensors and Actuators A: Physical</i>, <i>200</i>, 138–146. <a href="https://doi.org/10.1016/j.sna.2013.01.008">https://doi.org/10.1016/j.sna.2013.01.008</a>'
  bibtex: '@article{Al-Ashtari_Hunstig_Hemsel_Sextro_2013, title={Enhanced energy
    harvesting using multiple piezoelectric elements: Theory and experiments}, volume={200},
    DOI={<a href="https://doi.org/10.1016/j.sna.2013.01.008">10.1016/j.sna.2013.01.008</a>},
    journal={Sensors and Actuators A: Physical}, author={Al-Ashtari, Waleed and Hunstig,
    Matthias and Hemsel, Tobias and Sextro, Walter}, year={2013}, pages={138–146}
    }'
  chicago: 'Al-Ashtari, Waleed, Matthias Hunstig, Tobias Hemsel, and Walter Sextro.
    “Enhanced Energy Harvesting Using Multiple Piezoelectric Elements: Theory and
    Experiments.” <i>Sensors and Actuators A: Physical</i> 200 (2013): 138–46. <a
    href="https://doi.org/10.1016/j.sna.2013.01.008">https://doi.org/10.1016/j.sna.2013.01.008</a>.'
  ieee: 'W. Al-Ashtari, M. Hunstig, T. Hemsel, and W. Sextro, “Enhanced energy harvesting
    using multiple piezoelectric elements: Theory and experiments,” <i>Sensors and
    Actuators A: Physical</i>, vol. 200, pp. 138–146, 2013.'
  mla: 'Al-Ashtari, Waleed, et al. “Enhanced Energy Harvesting Using Multiple Piezoelectric
    Elements: Theory and Experiments.” <i>Sensors and Actuators A: Physical</i>, vol.
    200, 2013, pp. 138–46, doi:<a href="https://doi.org/10.1016/j.sna.2013.01.008">10.1016/j.sna.2013.01.008</a>.'
  short: 'W. Al-Ashtari, M. Hunstig, T. Hemsel, W. Sextro, Sensors and Actuators A:
    Physical 200 (2013) 138–146.'
date_created: 2019-05-13T13:51:59Z
date_updated: 2022-01-06T07:04:20Z
department:
- _id: '151'
doi: 10.1016/j.sna.2013.01.008
intvolume: '       200'
keyword:
- Energy harvesting
- Cantilever array
- Bandwidth
- Power increase
language:
- iso: eng
page: 138 - 146
publication: 'Sensors and Actuators A: Physical'
status: public
title: 'Enhanced energy harvesting using multiple piezoelectric elements: Theory and
  experiments'
type: journal_article
user_id: '55222'
volume: 200
year: '2013'
...
---
_id: '9796'
abstract:
- lang: eng
  text: 'A basic autonomous system powered by a piezoelectric harvester contains three
    components apart from the harvester: a fullwave rectifier, a reservoir capacitor
    and an electronic device performing the primary task of the system. In this contribution,
    a model describing the operation of such a system is derived. It is found that
    in steady-state operation, the piezoelectric harvester experiences two alternating
    load conditions due to the rectification process. These alternating load conditions
    can have a significant effect on the operation of the harvester and must be considered
    in the design of autonomous systems. The results also show that such an autonomous
    system works efficiently if it is connected to a high impedance load and excited
    by a frequency matching the anti-resonance frequency of the piezoelectric harvester.'
author:
- first_name: Waleed
  full_name: Al-Ashtari, Waleed
  last_name: Al-Ashtari
- first_name: Matthias
  full_name: Hunstig, Matthias
  last_name: Hunstig
- first_name: Tobias
  full_name: Hemsel, Tobias
  id: '210'
  last_name: Hemsel
- first_name: Walter
  full_name: Sextro, Walter
  id: '21220'
  last_name: Sextro
citation:
  ama: 'Al-Ashtari W, Hunstig M, Hemsel T, Sextro W. Characteristics of Piezoelectric
    Energy Harvesters in Autonomous Systems. In: <i>Proceedings of 10th International
    Workshop on Piezoelectric Materials and Applications and 8th Energy Harvesting
    Workshop, Hannover, Germany, 14.-17.7.2013</i>. Berichte aus dem IDS. Hannover,
    Germany; 2013:159-161.'
  apa: Al-Ashtari, W., Hunstig, M., Hemsel, T., &#38; Sextro, W. (2013). Characteristics
    of Piezoelectric Energy Harvesters in Autonomous Systems. In <i>Proceedings of
    10th International Workshop on Piezoelectric Materials and Applications and 8th
    Energy Harvesting Workshop, Hannover, Germany, 14.-17.7.2013</i> (pp. 159–161).
    Hannover, Germany.
  bibtex: '@inproceedings{Al-Ashtari_Hunstig_Hemsel_Sextro_2013, place={Hannover,
    Germany}, series={Berichte aus dem IDS}, title={Characteristics of Piezoelectric
    Energy Harvesters in Autonomous Systems}, number={05/2013}, booktitle={Proceedings
    of 10th International Workshop on Piezoelectric Materials and Applications and
    8th Energy Harvesting Workshop, Hannover, Germany, 14.-17.7.2013}, author={Al-Ashtari,
    Waleed and Hunstig, Matthias and Hemsel, Tobias and Sextro, Walter}, year={2013},
    pages={159–161}, collection={Berichte aus dem IDS} }'
  chicago: Al-Ashtari, Waleed, Matthias Hunstig, Tobias Hemsel, and Walter Sextro.
    “Characteristics of Piezoelectric Energy Harvesters in Autonomous Systems.” In
    <i>Proceedings of 10th International Workshop on Piezoelectric Materials and Applications
    and 8th Energy Harvesting Workshop, Hannover, Germany, 14.-17.7.2013</i>, 159–61.
    Berichte Aus Dem IDS. Hannover, Germany, 2013.
  ieee: W. Al-Ashtari, M. Hunstig, T. Hemsel, and W. Sextro, “Characteristics of Piezoelectric
    Energy Harvesters in Autonomous Systems,” in <i>Proceedings of 10th International
    Workshop on Piezoelectric Materials and Applications and 8th Energy Harvesting
    Workshop, Hannover, Germany, 14.-17.7.2013</i>, 2013, no. 05/2013, pp. 159–161.
  mla: Al-Ashtari, Waleed, et al. “Characteristics of Piezoelectric Energy Harvesters
    in Autonomous Systems.” <i>Proceedings of 10th International Workshop on Piezoelectric
    Materials and Applications and 8th Energy Harvesting Workshop, Hannover, Germany,
    14.-17.7.2013</i>, no. 05/2013, 2013, pp. 159–61.
  short: 'W. Al-Ashtari, M. Hunstig, T. Hemsel, W. Sextro, in: Proceedings of 10th
    International Workshop on Piezoelectric Materials and Applications and 8th Energy
    Harvesting Workshop, Hannover, Germany, 14.-17.7.2013, Hannover, Germany, 2013,
    pp. 159–161.'
date_created: 2019-05-13T13:53:25Z
date_updated: 2022-01-06T07:04:20Z
department:
- _id: '151'
issue: 05/2013
keyword:
- Energy harvesting
- harvester modeling
- load dependence
- generated voltage
language:
- iso: eng
page: 159-161
place: Hannover, Germany
publication: Proceedings of 10th International Workshop on Piezoelectric Materials
  and Applications and 8th Energy Harvesting Workshop, Hannover, Germany, 14.-17.7.2013
quality_controlled: '1'
series_title: Berichte aus dem IDS
status: public
title: Characteristics of Piezoelectric Energy Harvesters in Autonomous Systems
type: conference
user_id: '55222'
year: '2013'
...
---
_id: '9801'
author:
- first_name: Matthias
  full_name: Hunstig, Matthias
  last_name: Hunstig
- first_name: Waleed
  full_name: Al-Ashtari, Waleed
  last_name: Al-Ashtari
- first_name: Tobias
  full_name: Hemsel, Tobias
  id: '210'
  last_name: Hemsel
- first_name: Walter
  full_name: Sextro, Walter
  id: '21220'
  last_name: Sextro
citation:
  ama: 'Hunstig M, Al-Ashtari W, Hemsel T, Sextro W. Leistungs- und Bandbreitensteigerung
    von Energy-Harvesting-Generatoren für Energieautarke Systeme. In: Gausemeier J,
    Dumitrescu R,  Rammig F, Schäfer W, Trächtler A, eds. <i>9. Paderborner Workshop
    Entwurf Mechatronischer Systeme</i>. HNI-Verlagsschriftenreihe. Paderborn: Heinz
    Nixdorf Institut, Universität Paderborn; 2013:359-372.'
  apa: 'Hunstig, M., Al-Ashtari, W., Hemsel, T., &#38; Sextro, W. (2013). Leistungs-
    und Bandbreitensteigerung von Energy-Harvesting-Generatoren für Energieautarke
    Systeme. In J. Gausemeier, R. Dumitrescu, F.  Rammig, W. Schäfer, &#38; A. Trächtler
    (Eds.), <i>9. Paderborner Workshop Entwurf mechatronischer Systeme</i> (pp. 359–372).
    Paderborn: Heinz Nixdorf Institut, Universität Paderborn.'
  bibtex: '@inproceedings{Hunstig_Al-Ashtari_Hemsel_Sextro_2013, place={Paderborn},
    series={HNI-Verlagsschriftenreihe}, title={Leistungs- und Bandbreitensteigerung
    von Energy-Harvesting-Generatoren für Energieautarke Systeme}, booktitle={9. Paderborner
    Workshop Entwurf mechatronischer Systeme}, publisher={Heinz Nixdorf Institut,
    Universität Paderborn}, author={Hunstig, Matthias and Al-Ashtari, Waleed and Hemsel,
    Tobias and Sextro, Walter}, editor={Gausemeier, Jürgen and Dumitrescu, Roman and  Rammig,
    Franz and Schäfer, Wilhelm and Trächtler, AnsgarEditors}, year={2013}, pages={359–372},
    collection={HNI-Verlagsschriftenreihe} }'
  chicago: 'Hunstig, Matthias, Waleed Al-Ashtari, Tobias Hemsel, and Walter Sextro.
    “Leistungs- Und Bandbreitensteigerung von Energy-Harvesting-Generatoren Für Energieautarke
    Systeme.” In <i>9. Paderborner Workshop Entwurf Mechatronischer Systeme</i>, edited
    by Jürgen Gausemeier, Roman Dumitrescu, Franz  Rammig, Wilhelm Schäfer, and Ansgar
    Trächtler, 359–72. HNI-Verlagsschriftenreihe. Paderborn: Heinz Nixdorf Institut,
    Universität Paderborn, 2013.'
  ieee: M. Hunstig, W. Al-Ashtari, T. Hemsel, and W. Sextro, “Leistungs- und Bandbreitensteigerung
    von Energy-Harvesting-Generatoren für Energieautarke Systeme,” in <i>9. Paderborner
    Workshop Entwurf mechatronischer Systeme</i>, 2013, pp. 359–372.
  mla: Hunstig, Matthias, et al. “Leistungs- Und Bandbreitensteigerung von Energy-Harvesting-Generatoren
    Für Energieautarke Systeme.” <i>9. Paderborner Workshop Entwurf Mechatronischer
    Systeme</i>, edited by Jürgen Gausemeier et al., Heinz Nixdorf Institut, Universität
    Paderborn, 2013, pp. 359–72.
  short: 'M. Hunstig, W. Al-Ashtari, T. Hemsel, W. Sextro, in: J. Gausemeier, R. Dumitrescu,
    F.  Rammig, W. Schäfer, A. Trächtler (Eds.), 9. Paderborner Workshop Entwurf Mechatronischer
    Systeme, Heinz Nixdorf Institut, Universität Paderborn, Paderborn, 2013, pp. 359–372.'
date_created: 2019-05-13T14:02:10Z
date_updated: 2022-01-06T07:04:21Z
department:
- _id: '151'
editor:
- first_name: Jürgen
  full_name: Gausemeier, Jürgen
  last_name: Gausemeier
- first_name: Roman
  full_name: Dumitrescu, Roman
  last_name: Dumitrescu
- first_name: Franz
  full_name: ' Rammig, Franz'
  last_name: ' Rammig'
- first_name: Wilhelm
  full_name: Schäfer, Wilhelm
  last_name: Schäfer
- first_name: Ansgar
  full_name: Trächtler, Ansgar
  last_name: Trächtler
language:
- iso: eng
page: 359-372
place: Paderborn
publication: 9. Paderborner Workshop Entwurf mechatronischer Systeme
publisher: Heinz Nixdorf Institut, Universität Paderborn
series_title: HNI-Verlagsschriftenreihe
status: public
title: Leistungs- und Bandbreitensteigerung von Energy-Harvesting-Generatoren für
  Energieautarke Systeme
type: conference
user_id: '55222'
year: '2013'
...
---
_id: '9792'
abstract:
- lang: eng
  text: "''Energy Harvester`` wandeln Umgebungsenergie in nützliche elektrische Energie.
    Zur Berechnung der elektromechanischen Charakteristik eines piezoelektrischen
    ''Energy Harvesters\" wird ein auf Materialeigenschaften, Geometrie und Randbedingungen
    basierendes analytisches Modell vorgestellt. Dieses dient als Basis für ein weiteres
    Modell, welches den Betrieb eines autonomen Systems beschreibt. Die theoretischen
    Arbeiten werden mit Laborversuchen validiert. Es zeigt sich, dass der piezoelektrische
    Harvester im eingeschwungenen Zustand durch den Gleichrichtungsvorgang zwei abwechselnde
    Lastzustände erfährt. Dies führt zu nichtlinearem Verhalten des Harvesters, besonders
    wenn die angeschlossene Last eine geringe Impedanz hat. Desweiteren zeigen die
    Ergebnisse, dass ein solches autonomes System effizient arbeitet, wenn es an eine
    Last mit hoher Impedanz angeschlossen ist und bei einer der Antiresonanzfrequenz
    des piezoelektrischen Harvesters entsprechenden Frequenz angeregt wird.Das Modell
    des autonomen Systems wird auf ein System mit mehreren piezoelektrischen Wandlern
    erweitert. Zur praktischen Implementierung eines solchen Systems wird eine Technik
    zur Frequenzeinstellung eingeführt, da die optimalen Betriebsfrequenzen der einzelnen
    Wandler aufeinander abgestimmt werden müssen. Die Einstellung erfolgt, indem die
    Entfernung zwischen zwei Permanentmagneten und damit deren Anziehungskraft, welche
    die Steifigkeit des Harvesters beeinflusst, angepasst wird. Diese Technik zur
    Frequenzeinstellung wird modelliert und experimentell validiert. Die Ergebnisse
    zeigen, dass die Frequenzeinstellung mittels Permanentmagneten eine einfache und
    zugleich effektive Lösung für das Problem der Frequenzanpassung piezoelektrischer
    ''Energy Harvester\" darstellt. \r\nEnergy harvesters convert ambient energy into
    useful electrical energy. An analytical model for calculating the electromechanical
    characteristics of a piezoelectric harvester based on the material properties,
    geometry and boundary conditions is presented. This model is the basis for a further
    model which describes the operation of an autonomous system powered by a piezoelectric
    harvester. This theoretical work is validated by corresponding laboratory experiments.
    It is found that, in steady-state operation, the piezoelectric harvester experiences
    two alternating load conditions due to the rectification process. These load conditions
    make the system behave nonlinearly, especially if the connected electrical load
    is of low impedance. Furthermore, the results show that such an autonomous system
    works efficiently if it is connected to a high impedance load and excited at a
    frequency matching the anti-resonance frequency of the piezoelectric harvester.The
    model of an autonomous system is extended to describe a system with multiple piezoelectric
    transducers. For implementing such a system, the optimum operation frequencies
    of the individual transducers must be adjusted. Therefore, a frequency tuning
    method is introduced. The tuning is accomplished by adjusting the distance between
    two permanent magnets and thus changing the attracting force between them in order
    to affect the structural stiffness of the harvester. This tuning method is modeled
    and validated experimentally. The results show that frequency tuning using permanent
    magnets is a simple and effective solution for the frequency adjustment of piezoelectric
    energy harvesters."
author:
- first_name: Waleed
  full_name: Al-Ashtari, Waleed
  last_name: Al-Ashtari
citation:
  ama: Al-Ashtari W. <i>Model Based Enhancement of an Autonomous System with a Piezoelectric
    Harvester</i>. Shaker; 2013.
  apa: Al-Ashtari, W. (2013). <i>Model based enhancement of an autonomous system with
    a piezoelectric harvester</i>. Shaker.
  bibtex: '@book{Al-Ashtari_2013, title={Model based enhancement of an autonomous
    system with a piezoelectric harvester}, publisher={Shaker}, author={Al-Ashtari,
    Waleed}, year={2013} }'
  chicago: Al-Ashtari, Waleed. <i>Model Based Enhancement of an Autonomous System
    with a Piezoelectric Harvester</i>. Shaker, 2013.
  ieee: W. Al-Ashtari, <i>Model based enhancement of an autonomous system with a piezoelectric
    harvester</i>. Shaker, 2013.
  mla: Al-Ashtari, Waleed. <i>Model Based Enhancement of an Autonomous System with
    a Piezoelectric Harvester</i>. Shaker, 2013.
  short: W. Al-Ashtari, Model Based Enhancement of an Autonomous System with a Piezoelectric
    Harvester, Shaker, 2013.
date_created: 2019-05-13T13:47:14Z
date_updated: 2023-09-15T12:29:42Z
department:
- _id: '151'
language:
- iso: eng
publisher: Shaker
status: public
title: Model based enhancement of an autonomous system with a piezoelectric harvester
type: dissertation
user_id: '210'
year: '2013'
...
---
_id: '9781'
abstract:
- lang: eng
  text: 'A piezoelectric energy harvester is an electromechanical device that converts
    ambient mechanical vibration into electric power. Most existing vibration energy
    harvesting devices operate effectively at a single frequency only, dictated by
    the design of the device. This frequency must match the frequency of the host
    structure vibration. However, real world structural vibrations rarely have a specific
    constant frequency. Therefore, piezoelectric harvesters that generate usable power
    across a range of exciting frequencies are required to make this technology commercially
    viable. Currently known harvester tuning techniques have many limitations, in
    particular they miss the ability to work during harvester operation and most often
    cannot perform a precise tuning. This paper describes the design and testing of
    a vibration energy harvester with tunable resonance frequency, wherein the tuning
    is accomplished by changing the attraction force between two permanent magnets
    by adjusting the distance between the magnets. This tuning technique allows the
    natural frequency to be manipulated before and during operation of the harvester.
    Furthermore the paper presents a physical description of the frequency tuning
    effect. The experimental results achieved with a piezoelectric bimorph fit the
    calculated results very well. The calculation and experimental results show that
    using this tuning technique the natural frequency of the harvester can be varied
    efficiently within a wide range: in the test setup, the natural frequency of the
    piezoelectric bimorph could be increased by more than 70\%.'
author:
- first_name: Waleed
  full_name: Al-Ashtari, Waleed
  last_name: Al-Ashtari
- first_name: Matthias
  full_name: Hunstig, Matthias
  last_name: Hunstig
- first_name: Tobias
  full_name: Hemsel, Tobias
  id: '210'
  last_name: Hemsel
- first_name: Walter
  full_name: Sextro, Walter
  id: '21220'
  last_name: Sextro
citation:
  ama: Al-Ashtari W, Hunstig M, Hemsel T, Sextro W. Frequency tuning of piezoelectric
    energy harvesters by magnetic force. <i>Smart Materials and Structures</i>. 2012;21(3):035019.
  apa: Al-Ashtari, W., Hunstig, M., Hemsel, T., &#38; Sextro, W. (2012). Frequency
    tuning of piezoelectric energy harvesters by magnetic force. <i>Smart Materials
    and Structures</i>, <i>21</i>(3), 035019.
  bibtex: '@article{Al-Ashtari_Hunstig_Hemsel_Sextro_2012, title={Frequency tuning
    of piezoelectric energy harvesters by magnetic force}, volume={21}, number={3},
    journal={Smart Materials and Structures}, author={Al-Ashtari, Waleed and Hunstig,
    Matthias and Hemsel, Tobias and Sextro, Walter}, year={2012}, pages={035019} }'
  chicago: 'Al-Ashtari, Waleed, Matthias Hunstig, Tobias Hemsel, and Walter Sextro.
    “Frequency Tuning of Piezoelectric Energy Harvesters by Magnetic Force.” <i>Smart
    Materials and Structures</i> 21, no. 3 (2012): 035019.'
  ieee: W. Al-Ashtari, M. Hunstig, T. Hemsel, and W. Sextro, “Frequency tuning of
    piezoelectric energy harvesters by magnetic force,” <i>Smart Materials and Structures</i>,
    vol. 21, no. 3, p. 035019, 2012.
  mla: Al-Ashtari, Waleed, et al. “Frequency Tuning of Piezoelectric Energy Harvesters
    by Magnetic Force.” <i>Smart Materials and Structures</i>, vol. 21, no. 3, 2012,
    p. 035019.
  short: W. Al-Ashtari, M. Hunstig, T. Hemsel, W. Sextro, Smart Materials and Structures
    21 (2012) 035019.
date_created: 2019-05-13T13:16:33Z
date_updated: 2022-01-06T07:04:20Z
department:
- _id: '151'
intvolume: '        21'
issue: '3'
language:
- iso: eng
page: '035019'
publication: Smart Materials and Structures
quality_controlled: '1'
status: public
title: Frequency tuning of piezoelectric energy harvesters by magnetic force
type: journal_article
user_id: '55222'
volume: 21
year: '2012'
...
---
_id: '9782'
abstract:
- lang: eng
  text: Piezoelectric structures are nowadays used in many different applications.
    A better understanding of the influence of material properties and geometrical
    design on the performance of these structures helps to develop piezoelectric structures
    specifically designed for their application. Different equivalent circuits have
    been introduced in the literature to investigate the behaviour of piezoelectric
    transducers. The model parameters are usually determined from measurements covering
    the characteristic frequencies of the piezoelectric transducer. This article introduces
    an analytical technique for calculating the mechanical and electrical equivalent
    system parameters and characteristic frequencies based on material properties
    and geometry for a cantilever bimorph structure. The model is validated by measurements
    using a cantilever bimorph and fits the experimental results better than previous
    models. The model gives a full set of piezoelectric transducer parameters and
    is therefore well suited for further theoretical investigations of piezoelectric
    transducers for different applications. The results also show that even small
    manufacturing tolerances have a considerable effect on the system parameters and
    characteristic frequencies. This might lead to intolerable deviations, especially
    in dynamic applications and should be avoided by careful design and production.
author:
- first_name: Waleed
  full_name: Al-Ashtari, Waleed
  last_name: Al-Ashtari
- first_name: Matthias
  full_name: Hunstig, Matthias
  last_name: Hunstig
- first_name: Tobias
  full_name: Hemsel, Tobias
  id: '210'
  last_name: Hemsel
- first_name: Walter
  full_name: Sextro, Walter
  id: '21220'
  last_name: Sextro
citation:
  ama: Al-Ashtari W, Hunstig M, Hemsel T, Sextro W. Analytical determination of characteristic
    frequencies and equivalent circuit parameters of a piezoelectric bimorph. <i>Journal
    of Intelligent Material Systems and Structures</i>. 2012;23(1):15-23. doi:<a href="https://doi.org/10.1177/1045389X11430742">10.1177/1045389X11430742</a>
  apa: Al-Ashtari, W., Hunstig, M., Hemsel, T., &#38; Sextro, W. (2012). Analytical
    determination of characteristic frequencies and equivalent circuit parameters
    of a piezoelectric bimorph. <i>Journal of Intelligent Material Systems and Structures</i>,
    <i>23</i>(1), 15–23. <a href="https://doi.org/10.1177/1045389X11430742">https://doi.org/10.1177/1045389X11430742</a>
  bibtex: '@article{Al-Ashtari_Hunstig_Hemsel_Sextro_2012, title={Analytical determination
    of characteristic frequencies and equivalent circuit parameters of a piezoelectric
    bimorph}, volume={23}, DOI={<a href="https://doi.org/10.1177/1045389X11430742">10.1177/1045389X11430742</a>},
    number={1}, journal={Journal of Intelligent Material Systems and Structures},
    author={Al-Ashtari, Waleed and Hunstig, Matthias and Hemsel, Tobias and Sextro,
    Walter}, year={2012}, pages={15–23} }'
  chicago: 'Al-Ashtari, Waleed, Matthias Hunstig, Tobias Hemsel, and Walter Sextro.
    “Analytical Determination of Characteristic Frequencies and Equivalent Circuit
    Parameters of a Piezoelectric Bimorph.” <i>Journal of Intelligent Material Systems
    and Structures</i> 23, no. 1 (2012): 15–23. <a href="https://doi.org/10.1177/1045389X11430742">https://doi.org/10.1177/1045389X11430742</a>.'
  ieee: W. Al-Ashtari, M. Hunstig, T. Hemsel, and W. Sextro, “Analytical determination
    of characteristic frequencies and equivalent circuit parameters of a piezoelectric
    bimorph,” <i>Journal of Intelligent Material Systems and Structures</i>, vol.
    23, no. 1, pp. 15–23, 2012.
  mla: Al-Ashtari, Waleed, et al. “Analytical Determination of Characteristic Frequencies
    and Equivalent Circuit Parameters of a Piezoelectric Bimorph.” <i>Journal of Intelligent
    Material Systems and Structures</i>, vol. 23, no. 1, 2012, pp. 15–23, doi:<a href="https://doi.org/10.1177/1045389X11430742">10.1177/1045389X11430742</a>.
  short: W. Al-Ashtari, M. Hunstig, T. Hemsel, W. Sextro, Journal of Intelligent Material
    Systems and Structures 23 (2012) 15–23.
date_created: 2019-05-13T13:17:37Z
date_updated: 2022-01-06T07:04:20Z
department:
- _id: '151'
doi: 10.1177/1045389X11430742
intvolume: '        23'
issue: '1'
language:
- iso: eng
page: 15-23
publication: Journal of Intelligent Material Systems and Structures
quality_controlled: '1'
status: public
title: Analytical determination of characteristic frequencies and equivalent circuit
  parameters of a piezoelectric bimorph
type: journal_article
user_id: '55222'
volume: 23
year: '2012'
...
