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This is documentation for impact testing infrastructure, intended to measure peak acceleration and energy return of foam samples.

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The specs for the test are a mass of 7.8 kg, traveling at 1 m/s, with an circular impact area of diameter of 4 cm.
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<img src='impactor/release-design.png' height=220px>
<img src='impactor/testing.jpg' height=220px>
<img src='video/tracker.png' height=220px>
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<a href='https://gitlab.cba.mit.edu/calischs/foam-impact/tree/master/impactor'>impactor/</a> contains design files for a release mechanism for the mass.  This is built around a solenoid and a push-button quick release pin (90985A311 from McMaster-Carr).

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<a href='https://gitlab.cba.mit.edu/calischs/foam-impact/tree/master/pcb'>pcb/</a> contains design files and firmware for an embedded logging system using the ADXL372Z accelerometer and the Cortex M0 Adalogger board for Micro SD Card integration and battery management.

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<a href='https://gitlab.cba.mit.edu/calischs/foam-impact/tree/master/fw'>fw/</a> contains embedded code for detecting impact, sampling, and writing to the SD card.

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<a href='https://gitlab.cba.mit.edu/calischs/foam-impact/tree/master/analysis'>analysis/</a> contains an ipython notebook for analyzing the acceleration profiles, extracting peak acceleration levels and energy dissipation.
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<a href='https://gitlab.cba.mit.edu/calischs/foam-impact/tree/master/video'>video/</a> contains details of video analysis of the drop test.  For now, this is implemented with a Sony RX-100 IV camera shooting at 960 fps and the free software <a href='http://physlets.org/tracker/'>Tracker</a> to analyze acceleration profiles.
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<img src='impactor/adxl372z.jpg' height=300px>
<img src='impactor/instron.jpg' height=300px>

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<img src='analysis/img/asker-trajectories.png' height=300px>
<img src='analysis/img/asker-energies.png' height=300px>

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I've been using this measurement device to characterize the dynamics of folded foam samples I've been producing.  Below are the acceleration profiles of two folded samples compared against conventional foams.

<img src='analysis/impact-first-kiri.png' height=300px>