For the assumed deflection pattern given below, where u is taken as a prescribed displacement in the x direction, calculate the total potential energy for a square plate including the nonlinear effects in the midplane strain-displacement relations. The assumed displacement functions are
Note that the lateral deflection function is the usual one for a square, simplysupported plate. Thus it might be possible to simplify the bending strain energy of the plate by deleting the Gaussian curvature. Further, it might be pointed out that, as we shall verify later, the in-plane displacement harmonics were chosen so as to approximately satisfy the inplane equations of equilibrium.