Mechanical Trees Harvesting Vibration Energy: Renewable Electric Power

Summary: Mechanical trees harvesting vibration energy may power sensors and supplement such renewable electric power sources as solar panels and windmills.

Energy harvesting platform comprises primary structure of two L-shaped beams, clamped to an electrodynamic shaker table: Dan Zimmerman @N3OX, via Twitter Feb. 2, 2016

Mechanical trees harvesting vibration energy are possible renewable electric power sources in the early 21st century, according to research published for the Journal of Sound and Vibration issue of Feb. 17, 2016. 

One aerospace and mechanical engineer and two mechanical engineers base their findings upon investigations conducted at the Laboratory of Sound and Vibration Research in Columbus, Ohio. Their research concerns two small steel beams built through mathematical modeling and serving as a tree branch connected to a trunk by a polyvinylidene fluoride strip. Professors Harne of Columbus, Ohio, and Anqi Sun and Kon-Well Wang of Ann Arbor, Michigan, describe the strip as electromechanically converting structural oscillations into electrical energy.

The three researchers envision early, small-scale applications of L-shaped energy harvesters as voltage feeders to structural soundness-monitoring sensors on bridge undersides or on high-rise building girders.

The project flows from Professor Harne's postdoctoral research in Michigan and scientific interests in recovering and recycling "the plentiful vibrational energy that surrounds us every day."

Professor Harne, laboratory director and lead researcher and writer, goes to footfalls of bridge-crossing pedestrians, seismic activity and wind-shaken tree-like devices for renewable electric power sources. He holds that "Buildings sway ever so slightly in the wind, bridges oscillate when we drive on them and car suspensions absorb bumps in the road." He indicates that "In fact, there's a massive amount of kinetic energy associated with those motions that is otherwise lost" without mechanical trees harvesting vibration energy.

Energy-efficient inputs join energy-saving outputs when L-shaped energy harvesters, not expensive batteries or power line plug-ins, jump-start indoor, shaded structural soundness-monitoring sensors ineligible for solar-powered energy.

Electric-powered structural soundness-monitoring sensors keep current on the structural health and integrity of civil infrastructure, such as buildings and bridges, by keeping track of passing vibrations.

Mechanical trees harvesting vibration energy for renewable electric power sources let structural soundness-monitoring sensors link data acquisition regarding vibration frequency and data transmission regarding vibration energy. Generation of electricity by vibration-sensitive L-shaped energy harvesters makes it possible for structural soundness-monitoring sensors to "actually be powered by the same vibrations they are monitoring." And yet research results and suggested uses negate electromechanical assumptions regarding the unsuitability of random forces of nature for generating consistent oscillations and useful electrical energies.

The mathematical model that organizes the experimental test offers a consistent frequency and reliable voltage output despite high frequency forces and extra, non-idealized, random, realistic noise.

Mathematical modeling predicts the experimental test results because of internal resonance for dissipating internal energies in mechanical systems and saturation phenomena for reaching a tipping point.

Saturation phenomena quantify the transition of mechanical trees harvesting vibration energy with small amplitudes at high frequencies to harvesting vibrations with large amplitudes at low frequencies. "At first, to the eye," L-shaped energy harvesters reveal no movement when shaken back and forth even though the shakedown realizes electric outputs of 0.8 volts. Large amplitudes from high frequencies "significantly overwhelmed by extra random noise" contrastingly support two volts while synchronizing treelike branches and trunks swaying "noticeably back and forth."

Steady voltage output, albeit low at high frequencies with tree-nudging-like noise and lower without, tells us that batteries, plug-ins and renewable electric power sources have company.

Ryan Harne, director of Ohio State University's Laboratory of Sound and Vibration Research: Mechanical and Aerospace Engineering at Ohio State @OhioStateMAE, via Facebook Feb. 1, 2016

Acknowledgment

My special thanks to talented artists and photographers/concerned organizations who make their fine images available on the internet.

Image credits:

Energy harvesting platform comprises primary structure of two L-shaped beams, clamped to an electrodynamic shaker table: Dan Zimmerman @N3OX, via Twitter Feb. 2, 2016, @ https://twitter.com/N3OX/status/694576260874420224

Ryan Harne, director of Ohio State University's Laboratory of Sound and Vibration Research: Mechanical and Aerospace Engineering at Ohio State @OhioStateMAE, via Facebook Feb. 1, 2016, @ https://www.facebook.com/OhioStateMAE/posts/989178137794933

For further information:

Dan Zimmerman @N3OX. 2 February 2016. "'Leveraging nonlinear saturation-based phenomena in a ... vibration energy harvesting system.'" Twitter.
https://twitter.com/N3OX/status/694576260874420224

Gorder, Pam Frost. 1 February 2016. "Mechanical trees become power 'plants' when they sway in breeze." Phys.Org > Technology > Energy & Green Tech > Feb. 1, 2016.
Available @ http://phys.org/news/2016-02-mechanical-trees-power-sway-breeze.html

Gorder, Pam Frost. 1 February 2016. "Turning good vibrations into energy." Ohio State University News Room.
Available @ https://news.osu.edu/news/2016/02/01/shaketree/

Harne, R.L.; A. Sun; and K.W. Wang. 17 February 2016. "Leveraging nonlinear saturation-based phenomena in an L-shaped vibration energy harvesting system." Journal of Sound and Vibration, vol. 363: 517-531. DOI: 10.1016/j.jsv.2015.11.017
Available @ http://www.sciencedirect.com/science/article/pii/S0022460X15009141

Mechanical and Aerospace Engineering at Ohio State @OhioStateMAE. "Shared a link." Facebook. February 1, 2016.
Available @ https://www.facebook.com/OhioStateMAE/posts/989178137794933

Megiston. 2 February 2016. "Forget wind turbines: Artificial trees could produce power from the breeze and the sound of city." YouTube.
Available @ http://www.youtube.com/watch?v=5IJt_ZnxiaA

Phys.org @physorg_com. 1 February 2016. "Mechanical trees become power 'plants' when they sway in breeze." Twitter.
Available @ https://twitter.com/physorg_com/status/694178368313528320