college strength of material
posted by Nick .
i have initial and final gauge length and diameter and also have max load. Now i have to draw stress strain diagram. I know how to draw that graph but i a not provided with failure load or yield load so i am not sure how to graph. We had performed experiment and data was given by lecturer which had only one load data that is max load, no other points. Appreciate any help. Thanx in advance

Stress equals load divided by cross sectional area of test sample.
Strain equals [(Final length)(Initial Lelngth)]/(Initial Length)
Since you have only one data point, all you can plot is the stress (y axis) and strain (x axis) corresponding to breakage or yielding.
At loads less than the failure load, there should have been a linear relationship between stress and strain, with a slope equal to Young's modulus for the material. However, you say that you have no data points in this regime.
Reading this article may help you:
http://en.wikipedia.org/wiki/Stress%E2%80%93strain_curve 
Thnx drwl but i knw the fomulas but i dnt knw hw to plot a graph wen juz max load is given.

You can plot one point. That is all. If you were not told how much the sample stretched, you cannot even plot that.