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

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.

<img src='impactor/release-design.png' height=220px>
<img src='impactor/testing.jpg' height=220px>
<img src='video/tracker.png' height=220px>

<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).

<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.

<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.

<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.

<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.

<img src='impactor/turning-mass.jpg' height=300px>
<img src='impactor/milling-mass.jpg' height=300px>

<img src='impactor/adxl372z.jpg' height=300px>
<img src='impactor/instron.jpg' height=300px>

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


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' width=80%>