# Material Indices

1. Jul 16, 2010

### ganondorf29

I'm currently doing a project in my materials class and I wanted to check if these two material indices were right. The objectives are:
1. The material must not fracture
2. The material must be strong (no deformations)

Material Index 1
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Considering a yield-before-break scenario
Material Index = $$\frac{K_{1c}}{\sigma_{y}}$$
where K1c is the fracture toughness and sigma y is the yield strength

And for the plot would I put $${K_{1c}}$$ on the y-axis $${\sigma_{y}}$$ on the x axis, and pick the material near the upper right corner?

Material Index 2
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I want a really strong material that doesn't deform easily so is the material index this:

Material Index = $$E{\sigma_{y}$$

Here E is Young's Modulus and Sigma y is the yield strength. Also, how would you plot this?