Team:DTU-Denmark/Hardware
Hardware
An important part of this project was for us to be able to characterize the material properties of the fungus. We had specialized equipment at our disposal, but not everyone has, so we decided to make an alternative for future teams to be able to follow in our footsteps without the headache of needing very expensive machinery. We built a hydraulic press for us to perform compressive and tensile strength tests. These kinds of tests are needed in order to determine the stiffness of the material, which is an important factor for evaluating the viability of a building material.
This page will give a brief introduction to mechanical testing and the physics behind it, building instructions of the hydraulic, characterization and discussion of the press’s abilities.
Material characterization
When wanting to determine material characteristics, one way to do it, is to perform destructive tests. These tests enable us to accurately predict how a material will act when under load. An important parameter is Young's Modulus. It predicts how much a material sample extends under tension or shortens under compression. The Young's modulus directly applies to cases of uniaxial stress, that is tensile or compressive stress in one direction and no stress in the other directions. It is a measure of how stiff/rigid a material is in its linear region. When a material is experiencing stresses, in its linear region, it will return to its original shape when the stress is removed (elastic deformation). Outside of the linear region, in the non-linear region, the material will undergo permanent deformation until catastrophic failure.
Young’s modulus is defined as:
\begin{equation}
E = \frac{\sigma(\varepsilon)}{\varepsilon} = \frac{F / A}{\delta L / L_{0}} = \frac{FL_0}{A \delta L}
\end{equation}
E is the Young's modulus (modulus of elasticity) [Pa or N/m^2]
F is the force exerted on an object under tension
A is the actual cross-sectional area, which equals the area of the cross-section perpendicular to the applied force;
$\Delta\L$ is the amount by which the length of the object changes ( $\Delta\L$ is positive if the material is stretched , and negative when the material is compressed)
$L_{0}$ is the original length of the object.
During our testing we measured compressive strength. To get a more complete picture of the material properties of our fungi, we’d need to also perform tensile strength tests.
Building Instructions
