Select a material based on the simulation

Hello Vanessa:
When you do a linear elasticity simulation (the most common to study stresses, displacements and deformations) you must select a material from the library, or one defined by yourself.

Isotropic Linear Elasticity models the material using only a few material parameters: Young's modulus "E" (longitudinal elastic modulus) and Poisson's modulus "nu". The transverse elastic modulus "G" has a fixed relationship to them, so although it is among the material parameters, it is not really an independent variable.

Other elastic parameters, such as the limit stress of the elastic behaviour, or the yield stress or the rupture stress, are used for comparative purposes. That is, according to the Isotropic Linear Elastic model, stresses grow "linearly and can reach infinity"... because internally neither creep nor rupture is modelled. It only warns you when the elastic tensions approach the limit so that you can make the decision that this is neither possible nor correct. You can also report this situation through the FOS (Factor of Operation Safety), but it is always a comparison between what you calculated internally and what the real material supposedly resists.

For all this "you cannot give credit" to a linear elastic simulation when it shows stress values above the true elastic limit of the material, even though it is not exceeded in the rest of the piece. Simply, "if a part of the piece" requires stresses higher than those actually supported by the real material, then the general stress distribution will not be what this theory shows, and even, surely, a break will start in that area.

Finally, the parameters related to thermal behavior and others that appear in the material libraries definitely "do not affect the elastic results" (except when you solve a combined problem, thermoelasticity, for example).

What do I mean by all this talk?

That you could generate your own material for an elastic simulation, defining a few parameters and seeing if its behavior in the simulation is adequate. If it is, you could go find a real material that has those parameters or higher, and apply it in a new simulation to check that nothing has changed significantly.

For example, in uniaxial tensile tests, it is defined not only how much stress the material resists elastically, but also how much unit deformation it can resist (this can be observed in the post-processing of the linear simulation because "their theory does not consider that the deformation has a limit " but calculates it as if it could take any value).

If you want to take a simple look at the Theory of Linear Elasticity you can see it in my tutorials (no one reads them, by the way, hahaha).

Kind regards!

¯\_(ツ)_/¯ Why, whyyyyyyyyyy
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