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Energy Harvesting

EH cantilever beam with high resonant frequencies

Using the MFC for Energy Harvesting Applications

Moderator: TPD

EH cantilever beam with high resonant frequencies

Postby lowridaa » Sun May 21, 2017 10:00 am

Hello there,

i want to find out if one of the MFCs can be used for harvesting the energy of a vibration source with a high frequency.

The signal looks like this:

I did an FFT with Matlab that looks like this:

As you can see the most acceleration is at a frequency of about 1549Hz, other peaks are also interesting at 774.5Hz and 440Hz.

I want to evaluate the energy output of a piezoelectric energy harvester simulating the vibration source.

Since the cantilever beams in the evaluation kit have a much lower natural frequency, my question is if someone has information about the natural frequency of the MFCs not glued to another surface. Do you generelly think a MFC could fit my requirements and/or does anyone has experience with a smilar application?

Thank you in advance!
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Re: EH cantilever beam with high resonant frequencies

Postby TPD » Mon May 22, 2017 9:11 am


in general you need to redesign the cantilever to accomodate the higher resonance frequencies. Using the MFC without attachment to a structure (cantilever or similar) will not work because:
1) Using the MFC at your frequencies without any structure it is attached to will cause the neutral fiber be in the middle of the MFC and any generated electric charge of the top and bottom half will cancel each other out.

2) The thickness resonance of the MFC in air, without being attached to a structure is ~10MHz, the lateral resonance in fiber direction is ~40kHz and perpendicular to the fiber direction ~70kHz. So this is far higher than your frequency.

So you need to design a cantilever which has a resonance frequency around values you measured. This website gives you a good base for calculating the required material, size and thickness for a cantilever:

We believe you can definitely harvest energy with a proper designed cantilever/structure at the measured frequencies but only the experiment will show how much you can really retrieve for some useful application.
Smart Material Support Team
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