A Novel Full Stressed Energy Harvester with Varied Thickness

This study developed a novel full stressed energy harvester composed of a cantilever with varied thickness in the length direction to harvest energy from ambient vibrations. This harvester owns a higher efficiency of energy harvesting when compared with the harvester of a uniform cross section, since the maximum bending stress is constant in each cross section. The current available models for cantilever harvesters are inapplicable to the new improved fully stressed harvester due to its unique shape. By employing Rayleigh-Ritz method, a corresponding governing equation is hence developed to model the full stressed harvester for estimating the efficiency. The influence of the geometry on the generated electric power is also discussed for the full stressed harvester. The results show that the full stressed harvester can double the electric power generated by the uniform harvester, and the full stressed harvester has a lower natural frequency.

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Meniscus configurations and curvatures in non-axisymmetric pores of open and closed uniform cross section

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1987.0136 ◽

1987 ◽

Vol 414 (1846) ◽

pp. 111-133 ◽

Cited By ~ 20

Keyword(s):

Capillary Pressure ◽

Cross Section ◽

Meniscus Shape ◽

Tube Shape ◽

Unique Shape ◽

Uniform Cross Section ◽

Different Shapes ◽

Transition Points

Menisci that arise in pores of uniform cross section do not always have a unique shape. Occasionally, more than one shape is stable. The main features of the different shapes that can occur in uniform tubes are described. The meniscus shapes of perfectly wetting liquids in non-axisymmetric tubes formed from two rods separated from a plate are discussed and their meniscus curvatures calculated. Predictions are made of the spontaneous transitions from one meniscus shape to another with change in tube shape. Experiments with narrow tubes constructed from two rods separated from a plate confirmed the predicted meniscus shapes, curvatures and transition points and that curvature hysteresis in perfectly wetted tubes of uniform cross section is possible. The mechanism is distinct from accepted causes of capillary pressure hysteresis such as converging-diverging pore throats, condensation processes and wettability effects.

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Applicability analysis of a simplified numerical model of water and oil slug flow through capillary tubes of non-uniform cross-section area

Tyumen State University Herald Physical and Mathematical Modeling Oil Gas Energy ◽

10.21684/2411-7978-2019-5-2-71-88 ◽

2019 ◽

Vol 5 (2) ◽

pp. 71-88

Author(s):

Sergei V. Stepanov ◽

Georgii S. Bembel ◽

Aleksei Yu. Maksimov

Keyword(s):

Numerical Model ◽

Cross Section ◽

Slug Flow ◽

Capillary Tubes ◽

Cross Section Area ◽

Section Area ◽

Uniform Cross Section ◽

Flow Through

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Frequency equations for the flexural vibration of samples with a uniform cross-section

10.1063/5.0047850 ◽

2021 ◽

Author(s):

Anton Trník ◽

Igor Štubňa ◽

Libor Vozár

Keyword(s):

Cross Section ◽

Flexural Vibration ◽

Uniform Cross Section

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Theoretical and Experimental Studies on MEMS Variable Cross-Section Cantilever Beam Based Piezoelectric Vibration Energy Harvester

Micromachines ◽

10.3390/mi12070772 ◽

2021 ◽

Vol 12 (7) ◽

pp. 772

Author(s):

Xianming He ◽

Dongxiao Li ◽

Hong Zhou ◽

Xindan Hui ◽

Xiaojing Mu

Keyword(s):

Power Density ◽

Cantilever Beam ◽

Cross Section ◽

Energy Harvester ◽

Variable Cross Section ◽

Vibration Energy ◽

Variable Cross ◽

Vibration Energy Harvester ◽

Piezoelectric Vibration Energy Harvester ◽

Piezoelectric Vibration

The piezoelectric vibration energy harvester (PVEH) based on the variable cross-section cantilever beam (VCSCB) structure has the advantages of uniform axial strain distribution and high output power density, so it has become a research hotspot of the PVEH. However, its electromechanical model needs to be further studied. In this paper, the bidirectional coupled distributed parameter electromechanical model of the MEMS VCSCB based PVEH is constructed, analytically solved, and verified, which laid an important theoretical foundation for structural design and optimization, performance improvement, and output prediction of the PVEH. Based on the constructed model, the output performances of five kinds of VCSCB based PVEHs with different cross-sectional shapes were compared and analyzed. The results show that the PVEH with the concave quadratic beam shape has the best output due to the uniform surface stress distribution. Additionally, the influence of the main structural parameters of the MEMS trapezoidal cantilever beam (TCB) based PVEH on the output performance of the device is theoretically analyzed. Finally, a prototype of the Aluminum Nitride (AlN) TCB based PVEH is designed and developed. The peak open-circuit voltage and normalized power density of the device can reach 5.64 V and 742 μW/cm3/g2, which is in good agreement with the theoretical model value. The prototype has wide application prospects in the power supply of the wireless sensor network node such as the structural health monitoring system and the Internet of Things.

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

Sustainability ◽

10.3390/su13052865 ◽

2021 ◽

Vol 13 (5) ◽

pp. 2865 ◽

Cited By ~ 1

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.

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Vibrations of a timoshenko beam of non-uniform cross-section elastically restrained at one end and carrying a finite mass at the other

Ocean Engineering ◽

10.1016/0029-8018(91)90038-r ◽

1991 ◽

Vol 18 (1-2) ◽

pp. 129-145 ◽

Cited By ~ 2

Author(s):

R.H. Gutierrez ◽

P.A.A. Laura ◽

R.E. Rossi

Keyword(s):

Cross Section ◽

Timoshenko Beam ◽

The Other ◽

Finite Mass ◽

Uniform Cross Section ◽

Elastically Restrained

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Three-Dimensional Vibration Analysis of Twisted Cylinder With Sectorial Cross Section

Journal of Applied Mechanics ◽

10.1115/1.4007475 ◽

2013 ◽

Vol 80 (2) ◽

Cited By ~ 1

Author(s):

D. Zhou ◽

S. H. Lo

Keyword(s):

Cross Section ◽

Chebyshev Polynomial ◽

Numerical Solutions ◽

Twist Angle ◽

Ritz Method ◽

Three Dimensional ◽

Cylindrical Domain ◽

Linear Elasticity Theory ◽

Boundary Functions ◽

Polynomial Series

The three-dimensional (3D) free vibration of twisted cylinders with sectorial cross section or a radial crack through the height of the cylinder is studied by means of the Chebyshev–Ritz method. The analysis is based on the three-dimensional small strain linear elasticity theory. A simple coordinate transformation is applied to map the twisted cylindrical domain into a normal cylindrical domain. The product of a triplicate Chebyshev polynomial series along with properly defined boundary functions is selected as the admissible functions. An eigenvalue matrix equation can be conveniently derived through a minimization process by the Rayleigh–Ritz method. The boundary functions are devised in such a way that the geometric boundary conditions of the cylinder are automatically satisfied. The excellent property of Chebyshev polynomial series ensures robustness and rapid convergence of the numerical computations. The present study provides a full vibration spectrum for thick twisted cylinders with sectorial cross section, which could not be determined by 1D or 2D models. Highly accurate results presented for the first time are systematically produced, which can serve as a benchmark to calibrate other numerical solutions for twisted cylinders with sectorial cross section. The effects of height-to-radius ratio and twist angle on frequency parameters of cylinders with different subtended angles in the sectorial cross section are discussed in detail.

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The effect of type of sound damper material in the Helmholtz resonator to the output power spectrum of acoustic energy Harvester

Journal of Physics Theories and Applications ◽

10.20961/jphystheor-appl.v3i2.38148 ◽

2019 ◽

Vol 3 (2) ◽

pp. 50

Author(s):

Hedwigis Harindra ◽

Agung Bambang Setio Utomo ◽

Ikhsan Setiawan

Keyword(s):

Energy Harvesting ◽

Power Spectrum ◽

Electric Power ◽

Energy Harvester ◽

Helmholtz Resonator ◽

Acoustic Energy ◽

Acoustic Energy Harvesting ◽

Wasted Energy ◽

Second Peak ◽

Output Electric Power

Acoustic energy harvesting is one of many ways to harness acoustic noises as wasted energy into useful electical energy using an acoustic energy harvester. Acoustic energy harvester that tested by Dimastya (2018) which is consisted of loudspeaker and Helmholtz resonator, produced two-peak spectrum. It is suspected that the first peak is due to Helmholtz resonator resonance and the second peak comesfrom the resonance of the conversion loudspeaker. This research is to experimentally confirm the guess of the origin of the first peak. The experiments are performed by adding silencer materials on the resonator inner wall which are expected to be able to reduce the height of first peak and to know how they affect the output electric power spectrum of the acoustic energy harvester. Three different silencer materials are used, those are glasswool, acoustic foam, and styrofoam, with the same thickness of 12 cm. The results show that glasswool absorbs sound more effectively than acostic foam and styrofoam. The use of glasswool, acoustic foam, and styrofoam with 12 cm thickness lowered the first peak by 90% (from 39 mW to 0,5 mW), 82% (from 39 mW to 0,7 mW), and 82% (from 39 mW to 0,7 mW), respectively. Based on these results, it is concluded that the guess of the origin of the first peak is confirmed.

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