| 1. |
- Köhler, Elof, 1980, et al.
(författare)
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Impact of designed asymmetries on the effective bandwidth of a backfolded piezoelectric energy harvester
- 2019
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Ingår i: Sensors and Actuators, A: Physical. - : Elsevier BV. - 0924-4247. ; 292, s. 77-89
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Tidskriftsartikel (refereegranskat)abstract
- For the successful realization of autonomous wireless sensors, they will have to be able to harvest energy from their surroundings. Vibrational energy harvesting is one possible power source for wireless sensors, since vibrations are abundant in many environments. In order to make vibrational energy harvesters more useful, a broad bandwidth is desirable since many vibrations are stochastic in nature. In this paper we implement asymmetry to a backfolded piezoelectric energy harvester to achieve broader effective bandwidth with maintained power output. The optimized harvester achieves a minimum of 2.75 V in the frequency range 92–162 Hz with peak power output of 1.80 mW. Asymmetry based on different lengths of the conjoined cantilevers is experimentally and numerically shown to have the largest impact on the bandwidth, compared to the impact of modified mass loadings.
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| 2. |
- Staaf, Henrik, 1976, et al.
(författare)
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Achieving increased bandwidth for 4 degree of freedom self-tuning energy harvester
- 2018
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Ingår i: Journal of Sound and Vibration. - : Elsevier BV. - 1095-8568 .- 0022-460X. ; 420, s. 165-173
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Tidskriftsartikel (refereegranskat)abstract
- The frequency response of a self-tuning energy harvester composed of two piezoelectric cantilevers connected by a middle beam with a sliding mass is investigated. Measurements show that incorporation of a free-sliding mass increases the bandwidth. Using an analytical model, the system is explained through close investigation of the resonance modes. Resonance mode behavior further suggests that, by breaking the symmetry of the system, even broader bandwidths are achievable.
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| 3. |
- Staaf, Henrik, 1976, et al.
(författare)
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Effective piezoelectric energy harvesting with bandwidth enhancement by assymetry augmented self-tuning of conjoined cantilevers
- 2019
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Ingår i: International Journal of Mechanical Sciences. - : Elsevier BV. - 0020-7403. ; 150, s. 1-11
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Tidskriftsartikel (refereegranskat)abstract
- Vibrational energy harvesting offers a potential power supply for future intelligent wireless sensors. In order to make vibrational energy harvesters more useful, a broad bandwidth is desirable since many vibrations are stochastic in nature. In this paper we use a piezoelectric self-tuning energy harvester to demonstrate the importance of designing for asymmetry in a system of conjoined cantilevers. Asymmetry is achieved by varying the piezoelectric cantilever lengths as well as the proof mass weights. In addition to bandwidth broadening, a self-tuning effect is experimentally demonstrated by a sliding mass. The measurement results confirm previous model predictions.
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| 4. |
- Staaf, Henrik, 1976, et al.
(författare)
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Selftuning energy harvester by sliding weight
- 2017
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Ingår i: Svenska Mekanikdagarna 2017, 12-13 juni, Uppsala, Sverige.
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Konferensbidrag (refereegranskat)abstract
- This presentation reports design and measurements of a piezoelectric harvester with self-tuning for wider bandwidth and coupled piezoelectric cantilevers to maintain a high power output by extended strain distribution. The harvester is intended for powering sensors on gas turbines and has certain conditions on size, temperature and frequency
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| 5. |
- Staaf, Henrik, 1976, et al.
(författare)
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Smart design piezoelectric energy harvester with self-Tuning
- 2017
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Ingår i: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 922:1
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Konferensbidrag (refereegranskat)abstract
- Piezoelectric energy harvesting on a gas turbine implies constraints like high temperature tolerance, size limitation and a particular range of vibrations to utilise. In order to be able to operate under these conditions a harvester needs to be space effective and efficient and to respond to the appropriate range of frequencies. We present the design, simulation and measurements for a clamped-clamped coupled piezoelectric harvester with a free-sliding weight, which adds self-Tuning for improved response within the range of vibrations from the gas turbine. We show a peak open circuit voltage of 11.7 V and a 3 dB bandwidth of 12 Hz.
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| 6. |
- Staaf, Henrik, 1976, et al.
(författare)
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Verification of Self-Tuning 4DOF Piezoelectric Energy Harvester with Enhanced Bandwidth
- 2018
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Ingår i: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596.
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Konferensbidrag (refereegranskat)abstract
- In this paper, we present an analytical model to predict enhanced bandwidth for a piezoelectric energy harvester with self-tuning, accomplished by a sliding mass. The model predicts that by implementing asymmetry of different piezoelectric cantilever lengths , the bandwidth can theoretically approach 60 Hz. Validation measurements demonstrate an increased 3dB bandwidth up to 21 Hz with 150 mW, by configuration 23/17 mm in open length – providing sufficient power for a ZigBee to continually transmit.
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| 7. |
- Abadikhah, Hossein, 1987, et al.
(författare)
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A hierarchy of dynamic equations for micropolar plates
- 2015
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Ingår i: Journal of Sound and Vibration. - : Elsevier BV. - 1095-8568 .- 0022-460X. ; 357, s. 427-436
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Tidskriftsartikel (refereegranskat)abstract
- This work considers homogeneous isotropic micropolar plates adopting a power series expansion method in the thickness coordinate. Variationally consistent equations of motion and end boundary conditions are derived in a systematic fashion up to arbitrary order for extensional and flexural displacement cases. The plate equations are asymptotically correct to all studied orders. Numerical results are presented for various orders of the present method, other approximate theories as well as the exact three dimensional theory. The results illustrate that the present approach may render benchmark solutions provided higher order truncations are used, and act as engineering plate equations using low order truncation.
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| 8. |
- Abadikhah, Hossein, 1987, et al.
(författare)
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A hierarchy of dynamic equations for solid isotropic micropolar circular cylinders
- 2019
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Ingår i: Journal of Sound and Vibration. - : Elsevier BV. - 1095-8568 .- 0022-460X. ; 440, s. 70-82
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Tidskriftsartikel (refereegranskat)abstract
- This work considers the derivation procedure and evaluation of dynamic equations for isotropic micropolar circular cylinders by adopting a power series expansion method in the radial coordinate. Variationally consistent equations of motion together with pertinent sets of boundary conditions are expressed in a systematic fashion up to arbitrary order. The numerical results cover eigenfrequencies, mode shapes and field distributions over cross sections for axisymmetric and flexural motion adopting different sets of end boundary conditions for equations of different truncation orders of the present method. The results illustrate that the present approach may render benchmark solutions provided that higher order equations are used, and act as accurate approximate engineering solution for lower order equations.
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| 9. |
- Abadikhah, Hossein, 1987, et al.
(författare)
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A hierarchy of micropolar plate equations
- 2016
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Ingår i: 29th Nordic Seminar on Computational Mechanics.
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Konferensbidrag (refereegranskat)abstract
- This work considers homogeneous isotropic micropolar plates adopting a powerseries expansion method in the thickness coordinate. Equations of motion, forextensional and flexural case, together with consistent sets of end boundary conditionsare derived in a systematic fashion up to arbitrary order. The plateequations are asymptotically correct to all studied orders. Numerical results arepresented for various orders of the present method, other approximate theories aswell as the exact three dimensional theory. The results illustrate that the presentapproach may render benchmark solutions provided higher order truncatio
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| 10. |
- Abadikhah, Hossein, 1987, et al.
(författare)
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A rational derivation of dynamic higher order equations for functionally graded micropolar plates
- 2016
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Ingår i: Composite Structures. - : Elsevier BV. - 0263-8223. ; 153, s. 234-241
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Tidskriftsartikel (refereegranskat)abstract
- The dynamics of functionally graded micropolar plates is considered. The derivation process is based on power series expansions in the thickness coordinate. Using the three-dimensional equations of motion for micropolar continuum, variationally consistent equations of motion and end boundary conditions are derived in a systematic fashion up to arbitrary order. Numerical results are presented for simply supported plates using different material distributions for both low and high order truncation orders. These results illustrate that the present approach renders benchmark solutions provided higher order truncations are used, and act as engineering plate equations using low order truncation.
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