Teeth

Intrinsic mechanical property of a material independent of its geometry. From the slope of the stress vs. strain graph during an unconfined compression and considering the geometry of the sample, we can calculate the Young's modulus.

Lab Module — Unconfined compression of hydrogel disks

Lab Module — Tension and rupture of skin

The mechanical compliance is the inverse of the stiffness, it due to the deformation that occurs in the load cell, tester frame and mechanical setup during a mechanical test. When testing hard samples, this deformation may not be negligible; therefore, measurement of the setup compliance can be crucial in obtaining accurate mechanical properties. The tester compliance (or stiffness) depends on the tester configuration (e.g. height of the vertical stage on the frame, type of load cell, etc.) and the accessories installed. An easy way to measure the compliance of the tester is to replace the sample by a dummy sample much stiffer than the sample of interest (e.g. a piece of steel) or to remove the sample (for compression test) and then to apply a displacement. For example, if a flat indenter is contacted at the bottom of the testing chamber and a displacement is applied, the stage will be unable to move if the stiffness of the tester was infinite (zero compliance). In real situation, this would never be the case; the stage will be able to move but the load will increase rapidly. The entire mechanical setup can be modeled as two springs connected in series: one spring representing the tester stiffness and a second spring representing the sample stiffness. By looking at the load-displacement curve, the stiffness of the tester (or compliance) can be calculated.

Lab Module — Bending of bone