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Material, relationship between "E" and yield strength

Material, relationship between "E" and yield strength

Material, relationship between "E" and yield strength

(OP)
I am working on a plastics problem where there are a variety of formulations with a varitety of strength properties.  I can see that when the material Modulus of Elasticity, E increases the yield strength does as well, and vice versa.  Is there a real realationship here?  If I get a range of E values and a range of yield values is it correct to assume that there is a linear relationship between the max and min values of each.

Thanks

EngForm78  

RE: Material, relationship between "E" and yield strength

Hi,

do you mean the yield stress?
If yes, as far as I know, there is no such relationship.

Alex

RE: Material, relationship between "E" and yield strength

There is no linear relationship . This is why plastic analysis in non-linear.In FEA for plastic analysis stress strain data is input in preprocessor and strain is calculated in solve. Then stress is calculated/charted from calculated strain values. So your stress/strain input data is very important because if input stress values are not correct, then postprocessor stresses will be wrong.

good57morning@netzero.com

RE: Material, relationship between "E" and yield strength

feadude,

i think engform78 was asking is the a relationship between yield stress and E; rather than stress = E*strain.

as mihaiupb notes, there isn't.  different "flavours" of Al (2024, 7075) have the same E, but different yields.

RE: Material, relationship between "E" and yield strength

Engforum78,

It is just a coincidence and there is no linear relationship. For a lot of metals, the stronger they are, the stiffer they are.

A simple exception is Titanium which is not very stiff compared to steel but is stronger than many steels. Titanium is not, however stronger than the strongest steels.

RE: Material, relationship between "E" and yield strength

Most steels have similar E's, although yield varies widely.

I'm sure if you narrow the material down sufficiently, you can get some sort of relationship.  For example, I think ACI has a formula for E vs. fc' for concrete.  If you were just varying one component of the plastic, you could probably do something similar.

I seem to recall from long ago that E with plastics was also time dependent, which would further complicate matters.

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