====== Units ======

In Metafor, as in most FE codes, units are not explicitly defined. The user must enter input data in a consistent way. 

^	   ^  SI                        ^  SI (mm)              ^	
|Length    |  $\mbox{m}$	        |  $\mbox{mm}$	        |
|Force     |  $\mbox{N}$	        |  $\mbox{N}$	        |
|Mass      |  $\mbox{kg}$	        |  $\mbox{tonne}$ 	|
|Time      |  $\mbox{s}$	        |  $\mbox{s}$	        | 
|Stress    |  $\mbox{Pa } \left ( \mbox{N}/\mbox{m}^2 \right ) $  |  $\mbox{MPa } \left ( \mbox{N}/\mbox{mm}^2 \right ) $	|
|Energy    |  $\mbox{J}$	        |  $\mbox{mJ } \left ( 10^{–3} \mbox{J} \right ) $  |
|Density   |  $\mbox{kg/m³}$       |  $\mbox{tonne} / \mbox{mm}^3$	|

For example, if the geometry (point coordinates) is expressed in meters and the boundary conditions (loads) in Newton, the Young's Modulus appearing in the material definition must be expressed in $\mbox{N/m}^2$. Likewise, a geometry in meters and a Young's Modulus in $\mbox{kg/m}^2$ lead to forces in $\mbox{kg}$.