Finite Element programs, just like drawing programs, are insensitive to units: you may calculate something in units as small as a micrometer (10-6 m) or as large as a kilometer (103 m), or even larger, and receive the exact same answer. Well, that is, in different units. The same applies to loads, stresses and the like. Likewise, the use of the iMesh applet does not require you to use any particular units, and you can even work in pounds (lbs) and inches (in), as long as your units are consistent. This means that all units that use must be compatible with one another. If your lengths are in millimeters [mm] and your stresses in [N/mm2], then your forces consequently need to be in [N].
If you are not interested in this matter, please feel free to skip the following paragraph, and to visit read it at a later time. It is not required that you understand these concepts to complete this tutorial
Proposed units: meter, MegaNewton and MegaPascal
The iMesh applet proposes as its default units: meters [m], MegaPascal [MPa] and MegaNewton [MN]. The default value for the thickness of the concrete elements (0.3 [m]), the default diameter of the reinforcing bars (0.02 [m], that is 20 [mm]) and the default material properties for concrete (fc = 20 [MPa], Ec = 30’000 [MPa]) and steel (fs = 500 [MPa], Es = 205’000 [MPa]). But you are free to change these values by editing them in the iMesh text input file.
