Power Density Performance Improvements for High Pressure Ripple Energy Harvesting

A hydraulic pressure energy harvester (HPEH) device, which utilizes a housing to isolate a piezoelectric stack from the hydraulic fluid via a mechanical interface, generates power by converting the dynamic pressure within the system into electricity. Prior work developed an HPEH device capable of generating 2187 microWatts from an 85 kPa pressure ripple amplitude using a 1387 mm3 stack. A new generation of HPEH produced 157 microWatts at the test conditions of 18 MPa static pressure and 394 kPa root-mean-square pressure amplitude using a 50 mm3 stack, thus increasing the power produced per volume of piezoelectric stack principally due to the higher dynamic pressure input. The stack and housing design implemented on this new prototype device yield a compact, high-pressure hydraulic pressure energy harvester designed to withstand 35 MPa. The device, which is less than a 2.54 cm in length as compared to a 5.3 cm length of a previous HPEH, was statically tested up to 21.9 MPa and dynamically tested up to 19 MPa with 400 kPa root-mean-square dynamic pressure amplitude. An inductor was included in the load circuit in parallel with the stack and the load resistance to increase the power output of the device. A previously developed electromechanical power output model for this device that predicts the power output given the dynamic pressure ripple amplitude is compared to the power results. The power extracted from this device would be sufficient to meet the proposed applications of the device, which is to power sensor nodes in hydraulic systems.

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Design and Modeling of Hydraulic Pressure Energy Harvesters for Low Dynamic Pressure Environments

Volume 4B: Dynamics, Vibration, and Control ◽

10.1115/imece2014-38684 ◽

2014 ◽

Cited By ~ 1

Author(s):

Ellen Skow ◽

Kenneth Cunefare ◽

Alper Erturk

Keyword(s):

High Pressure ◽

Piezoelectric Material ◽

Load Transfer ◽

Dynamic Pressure ◽

Distribution Networks ◽

Sensor Nodes ◽

Hydraulic Pressure ◽

Cross Sectional ◽

Energy Harvesters ◽

Pressure Ripple

Hydraulic Pressure Energy Harvesters (HPEHs) use the direct piezoelectric effect to extract electrical power from the dynamic pressure ripple present in hydraulic systems. As with other energy harvesters, an HPEH is intended to be an enabling technology for powering sensor nodes. To date, HPEH devices have been developed for high-pressure, high-dynamic pressure ripple systems. High-pressure applications are common in industrial hydraulics, where static pressures may be up to 35 MPa. Other fluid systems, such as cross-country pipelines as well as water distribution networks operate at much lower pressures, e.g., from around 1 to 4 MPa, with proportionally lower dynamic pressures. Single-crystal piezoelectric materials are incorporated into the HPEH design, along with means to increase the load transfer into the piezoelectric material as well as increased output harvester circuits, so as to increase the power output of these devices. The load transfer from the pressurized fluid into the piezoelectric material is through an interface, where the interface area may be designed such that the area exposed to the fluid is greater than the cross-sectional area of the piezoelectric, yielding higher stress in the material than the pressure in the fluid. Furthermore, given the relatively large capacitance of the piezoelectric elements used in HPEH devices, inductive-tuned resonant harvester circuits implemented with passive elements are feasible. HPEH devices integrating these features are shown to produce viable power outputs from low dynamic pressure systems.

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Energy Harvesting From Hydraulic Pressure Fluctuations

Volume 2: Mechanics and Behavior of Active Materials; Integrated System Design and Implementation; Bio-Inspired Materials and Systems; Energy Harvesting ◽

10.1115/smasis2012-7926 ◽

2012 ◽

Cited By ~ 2

Author(s):

Kenneth A. Cunefare ◽

Nalin Verma ◽

Alper Erturk ◽

Ellen Skow ◽

Jeremy Savor ◽

...

Keyword(s):

Energy Harvesting ◽

Power Output ◽

Energy Harvester ◽

Dynamic Pressure ◽

High Energy ◽

Sensor Nodes ◽

Hydraulic Systems ◽

Mean Pressure ◽

Pressure Ripple ◽

The Mean

State-of-the-art hydraulic hose and piping systems employ integral sensor nodes for structural health monitoring in order to avoid catastrophic failures. These systems lend themselves to energy harvesting for powering sensor nodes. The foremost reason is that the power intensity of hydraulic systems is orders of magnitude higher than typical energy harvesting sources considered to date, such as wind turbulence, water flow, or vibrations of civil structures. Hydraulic systems inherently have a high energy intensity associated with the mean pressure and flow. Accompanying the mean pressure is what is termed dynamic pressure ripple caused by the action of pumps and actuators. Pressure ripple is conducive to energy harvesting as it is a deterministic source with an almost periodic time domain behavior. Pressure ripple generally increases in magnitude with the mean pressure of the system, which in turn increases the power that can be harvested. The harvested energy in hydraulic systems could enable self-powered wireless sensor nodes for applications such as energy-autonomous structural health monitoring and prognosis. An energy harvester prototype was designed for generating low-power electricity from dynamic pressure ripples. The prototype employed an axially-poled off-the-shelf piezoelectric stack. A housing isolated the stack from the hydraulic fluid while maintaining mechanical coupling to the system to allow for dynamic pressure induced deflection of the stack. The system exhibits an attractive off-resonance energy harvesting problem since the fundamental resonance of the piezoelectric stack is much higher than the frequency content of ripple. Although the energy harvester is not excited at resonance, the high energy intensity of the ripple results in significant electrical power output. The prototype provided a maximum output of 1.2 mW at 120Ω. With these results, it is clear that the energy harvester provides non-negligible power output suitable for powering sensors and other low power components. This work also presents electromechanical model simulations for predicting the piezoelectric power output in terms of the force transmitted from the pressure ripple as well as experimental characterization of the power output as a function of the force from the ripple.

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Input-dependent performance study of a nonlinear piezoelectric energy harvester

Journal of Intelligent Material Systems and Structures ◽

10.1177/1045389x16651156 ◽

2016 ◽

Vol 28 (5) ◽

pp. 619-626 ◽

Cited By ~ 3

Author(s):

Wei Deng ◽

Ya Wang

Keyword(s):

Root Mean Square ◽

Principal Components ◽

Energy Harvester ◽

Amplitude Ratio ◽

Principal Component ◽

Magnetic Interaction ◽

Mean Square ◽

Performance Study ◽

Piezoelectric Energy ◽

Voltage Output

This work reports an input-dependent performance study of a nonlinear piezoelectric energy harvester with introduced magnetic interaction. The performances of the novel harvester with two external magnet arrays (I and II) are compared. Array II that has symmetric magnetic force yields better voltage output under frequency sweep test. As such, the energy harvesting capacity with Array II is performed under two vibration inputs (I and II). Under excitation Input I with periodic varying frequency, experimental results show that the nonlinear piezoelectric harvester outperforms its linear counterpart (no magnetic interaction) at alternating input bandwidths. A 104.5% improvement of root mean square voltage output (318.2% of power output) is obtained under excitation of 0.334 g (root mean square) and bandwidth of 7 Hz. No advantage is observed under Input II consisting of one principal and finite non-principal components. However, detailed study indicates that the amplitude of the principal component and the amplitude ratio of the non-principal components to the principal component in Input II are essential to maintain large-amplitude periodic motion. Our work provides useful insights into the design, characterization, and application of nonlinear energy harvesters with external magnetic forces based on a priori knowledge of input.

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Pressure and Traction Rippling in Elastohydrodynamic Contact of Rough Surfaces

Journal of Lubrication Technology ◽

10.1115/1.3451975 ◽

1974 ◽

Vol 96 (3) ◽

pp. 398-406 ◽

Cited By ~ 15

Author(s):

T. E. Tallian

Keyword(s):

High Pressure ◽

Rough Surfaces ◽

Mean Value ◽

Surface Plastic ◽

Two Dimensional ◽

Plateau Region ◽

Pressure Ripple ◽

Ripple Amplitude ◽

Roll Velocity ◽

The Mean

Local variations in asperity dimensions (rippling) of elastohydrodynamic (EHD) pressure are calculated using Christensen’s stochastic model of the hydrodynamics of heavily loaded two-dimensional contacts between rough surfaces. Pressure ripple amplitudes of the order of the maximum Hertz pressure, i.e., well in excess of 105 psi (69.107 N/m2) are predicted at the inlet perimeter of the EHD contact plateau and at the upstream slope of the exit constriction for heavily loaded contacts, if the plateau film thickness to rms roughness ratio is h/σ = 2. Pressure ripple amplitudes in excess of 104 psi (69.106 N/m2) are probable even for the thick film condition h/σ = 10. Sliding traction rippling is calculated for small slide/roll velocity ratios in the same type of contact, and ripple amplitudes in excess of the mean value of the traction are predicted in the high pressure EHD plateau region of the contact for h/σ = 3. The predicted traction ripple amplitude exceeds 30 percent of the mean traction, even for h/σ = 6. Rippling increases the average traction over that for smooth surfaces. Both the pressure and traction rippling may contribute to surface plastic flow and fatigue.

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Neuromuscular Adjustments Following Sprint Training with Ischemic Preconditioning in Endurance Athletes: Preliminary Data

Sports ◽

10.3390/sports9090124 ◽

2021 ◽

Vol 9 (9) ◽

pp. 124

Author(s):

Stéphan Bouffard ◽

Pénélope Paradis-Deschênes ◽

François Billaut

Keyword(s):

Root Mean Square ◽

Ischemic Preconditioning ◽

Power Output ◽

Wingate Test ◽

Peak Power Output ◽

Mean Square ◽

Sprint Training ◽

Mean Power ◽

Root Mean Square Amplitude ◽

Mean Power Frequency

This preliminary study examined the effect of chronic ischemic preconditioning (IPC) on neuromuscular responses to high-intensity exercise. In a parallel-group design, twelve endurance-trained males (VO2max 60.0 ± 9.1 mL·kg−1·min−1) performed a 30-s Wingate test before, during, and after 4 weeks of sprint-interval training. Training consisted of bi-weekly sessions of 4 to 7 supra-maximal all-out 30-s cycling bouts with 4.5 min of recovery, preceded by either IPC (3 × 5-min of compression at 220 mmHg/5-min reperfusion, IPC, n = 6) or placebo compressions (20 mmHg, PLA, n = 6). Mechanical indices and the root mean square and mean power frequency of the electromyographic signal from three lower-limb muscles were continuously measured during the Wingate tests. Data were averaged over six 5-s intervals and analyzed with Cohen’s effect sizes. Changes in peak power output were not different between groups. However, from mid- to post-training, IPC improved power output more than PLA in the 20 to 25-s interval (7.6 ± 10.0%, ES 0.51) and the 25 to 30-s interval (8.8 ± 11.2%, ES 0.58), as well as the fatigue index (10.0 ± 2.3%, ES 0.46). Concomitantly to this performance difference, IPC attenuated the decline in frequency spectrum throughout the Wingate (mean difference: 14.8%, ES range: 0.88–1.80). There was no difference in root mean square amplitude between groups. These preliminary results suggest that using IPC before sprint training may enhance performance during a 30-s Wingate test, and such gains occurred in the last 2 weeks of the intervention. This improvement may be due, in part, to neuromuscular adjustments induced by the chronic use of IPC.

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