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Strain-Tension Recorder Engineered from Cheap Hardware

2017-04-03 11.33.13 copy.jpg


STRECH is an arduino-based, cheap and portable materials testing device that can be used in classroom and outreach settings. It was designed to easily perform dynamic strain-tension tests on rubberbands and to engage users in the activity of designing experiments and collecting data. Currently, STRECH is implemented as a shield that can be directly plugged into an arduino uno. The shield includes a push button, LEDs, and a piezo buzzer for user interaction as well as an onboard instrumentation amplifier to enhance the input signals.

How does it work


The physical testing apparatus involves a car in a track. The sample to be tested (usually a rubberband) is attached to the back of the car via a hook and to the track via a force transducer, which acts as a miniature scale. The front of the car houses an ultrasonic range finder that is continually measuring the distance from the front of the car to the end of the track.

carStretched.png As the car is moved forward on the track, the sample is stretched and applies force to the force transducer. Also, the new distance between the front of the car and the end of the track can be used to calculate how much the car has moved, which is equal to how much the sample has stretched. These data are continuously recorded by the arduino and combined to form a strain-tension dataset.



Table of parts with links and costs




  • make wiki public
  • create hardware table
  • make video to demonstrate usage
  • convert R code to processing
  • test software on cheap arduino clone
  • order parts to make 5 shields for demos
  • design replacements for aluminum track to be 3d printed
  • create demonstration video
  • create build tutorial for breadboard
  • create build tutorial for shield
  • consider making custom pcb