Homework Help: Modulus of Elasticity

1. Feb 10, 2013

jabers

The engineering yield strength, the modulus of elasticity, the original diameter and final diameter of a wire are given. That wire is stretched and it diameter decreases. I am trying to find the engineering strain just before yield and the corresponding true strain.

So I assume I will find that the engineering strain is equal to or very close to the true strain because their curves don't diverge, in my experience, until necking occurs but I have to show that is the case. I believe that the yield strength is at the yield stress so a good approximation would be the proportionality limit.

My problem is that there are no specifics about the modulus elasticity. If it is young's modulus then I can find the lateral strain from hooke's law but then because I don't know the original or final lengths I don't know how to compare it to the true strain. Is there another law that I am forgetting about? Is hooke's law applicable for the longitudinal case?

2. Feb 12, 2013

pongo38

Young's modulus is another name for the modulus of elasticity. Hooke's law applies longitudinally, in addition to other axes.

3. Feb 12, 2013

Staff: Mentor

What do you mean by the "longitudinal case"?