Calculate Proportional Limit of Alloy Bar

[JSBeckton]

I am given the length, elongated length, original diameter and reduced diameter of a alloy bar, and the load carried. I need to calculate the mod of elasticity, poisson's ratio and the proportional limit for the material. Got the first 2, how do I calculate the proportional limit? My book it quite vague, as if its obvious, which I'm sure that it is but I missed it, can anyone tell me what i need to do? Thanks

 

[JSBeckton]

nevermind, I got it

 

[quicknote]

To calculate the proportional limit of the alloy bar, you will need to use the stress-strain curve for the material. This curve shows the relationship between the stress applied to the material and the resulting strain, or deformation, of the material.

The proportional limit is the point on the stress-strain curve where the material begins to exhibit non-linear behavior, meaning that the relationship between stress and strain is no longer a straight line. This is typically represented by a sudden increase in the slope of the curve.

To determine the proportional limit, you will need to plot the stress-strain data for the alloy bar and visually identify the point where the curve deviates from a straight line. This point will be the proportional limit.

Alternatively, you can also calculate the proportional limit by finding the stress value at which the strain is equal to 0.2%. This is the standard definition of proportional limit and can be found by dividing the stress at 0.2% strain by the original cross-sectional area of the bar.

It is important to note that the proportional limit is a critical value for a material, as it marks the point where the material begins to permanently deform and may no longer return to its original shape. Therefore, it is an important parameter to consider when designing and using materials for different applications.