SaM - Young and Poisson Modulus

• Let’s define the ratio between the applied pressure (uniaxial stress) and deformation (or strain, this ratio is called the “Young modulus”.
  ==For isotropic materials, the Young modulus is independent on the direction of application of the force==.
• Then I also define the “Poisson module”, which represents the ratio between the perpendicular strain (with respect to the applied force) and the parallel strain.
  ==Again for isotropic materials, this is a number and doesn’t depend on the direction of application of the force.==

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In Higher Dimensions

If we go to higher dimensions, if we use uniaxial stress, it does not change at all:

• $\left[{\sigma }_1,\dots ,0\right]$ is the stress vector.

IMPORTANTE Otherwise, for higher dimensions we need to use the “Hooke’s law”.