Today we conducted a tensile strength test on the three specimens which we made previously (1). We started our testing at the faculty of Industrial Design Engineering (IDE) with a universal testing machine (UTM) which was made by a student. However due to problems with the software, we could not get results with it. We therefore went to the 3me faculty to do the test with a ZwickZ100 UTM (2) in combination with an extensometer (which was used to more accurately measure the change in length of the specimen).
From this test we learned that the ridged specimen breaks at 40.64 MPa and the composite at 10.27 MPa (however the last one broke not in the middle, but the bottom part was ripped off). The UTM machine was not able to measure the most flexible material as no force was build up for measurement.
Next week, we will do more tensile testing, again with the soft material, but also with another new specimen (60% ridged, 40% soft material) as this will probably be the composite material we will use for the gripper-finger.
First tensile strength test set-up at IO. However because of software problems this did not work well.
The ZwickZ100 UTM just broke the rigid specimen in half.
Remains of the specimen.
(1) Weblog post, 1 October 2015, https://softrobotics2015.weblog.tudelft.nl/2015/10/01/connex-printing-test/
(2) Zwick Roell Group, http://www.zwick.com/