I am going to be doing an experiment soon using strain gauges on a beam and I will have to, among other things, calculate the direction of the maximum shear strain with respect to the axis of the beam. I am trying to find the correct equation to use.
The Attempt at a Solution
I have found this equation in a text book of mine: tan2θ = - (εxx - εyy) / 2εxy. I looks to me like the right one but the text is a bit ambiguous. I know this isn't a very specific question but is this the equation I would need to calculate what I said above? I just want to know roughly what I'm doing before I go to the lab.