Jordi Serra Espaulella focused its efforts in modify the machine hardware and software originally created by the student Marcel Pla in his TFG of Mechatronic Engineering studies in 2018. The Tensile Testing Machine has been redesigned on the base of open source hardware and software (OSH and OSS) and is now able to perform tensile, compression and cyclic tests.

The original design by Marcel Pla included a off the shelf, proprietary LabJack module which generates and reads all the control signals, with software and graphical user interface designed with Matlab.

Jordi Serra Espaulella replaced the Labjack module with an open source, user friendly and well known Arduino board. The Krenel load cell amplifier has been replaced by an HX711 amplifier that has the advantage of integrating a 24-bit analog to digital converter (definitely better than the Arduino 10-bit ADC). Even more, it is already available an open source pre-compiled library that allows users to work with the HX711 and the Arduino microcontrollers. On the other side, the main disadvantage is that the acquisition speed is limited to 10 to 80 samples per second. However, this is not a severe limitation, as typical tests are usually done at slow speeds. The motor controller was replaced by a Trinamic brand driver that generates step interpolation and makes the system very noiseless, as well as notably reducing vibrations. From the software point of view, Jordi Serra completely rewritten the control code and designed a new, user friendly graphical user interface in Python.

 

Herewith the first measurements in cyclic tests.