Thank you for your response and insight!
I am going to try to use the curved neutral axis as my datum and see if this will work for my problem. I am assuming (or I think elasticity assumes) that the solution for the displacement of the surface will follow the displacement of the neutral axis...
I am trying to solve for the deflection and stress in a tapered beam (constant width b) shown in the attachment, and I am getting confused by at least 2 things: 1) how to deal with the "imposed" coordinate system, 2) the nonsymmetric shape and the corresponding neutral axis. [Assume that the...