This week we conducted quasi-static compression tests on our 5% and 10% hemp foam samples. To analyze the data, we graphed stress vs. strain. We found Young's modulus, the yield strength, which is the stress at the point where the material is no longer elastic, and the densification point, which is a point that defines when the material moves from its plastic state and behaving like a foam to being very compressed so that it no longer behaves like a foam.

In addition we performed dynamic compression testing on the 5% and 10% foam samples. The sample was placed between 2 metal rods. A strain gauge was attached to stationary rods on each side of sample to measure the elongation of the rods as the wave passes through. The strain gauge was connected across a Wheatstone bridge and the data was displayed on an oscilloscope. Compressed air pushed a smaller metal rod into one of the stationary rods that touched one side of the sample. A piece of copper was placed on the metal rod touching the sample so that when the compressed air pushes the smaller rod into it, there is a more gradual increase in the force applied. This is needed so that the sample is in equilibrium; that is, the force on the sample from the stationary rods on each side are equal. We then analyzed graphs that were created of the impulse through the rods and stress vs. strain.