New Fourth Order Postprocessing Techniques for Plate Buckling Eigenvalues by Morley Element

In this paper, we propose and analyze the extrapolation methods and asymptotically exact a posterior error estimates for eigenvalues of the Morley element. We establish an asymptotic expansion of eigenvalues, and prove an optimal result for this expansion and the corresponding extrapolation method. We also design an asymptotically exact a posterior error estimate and propose new approximate eigenvalues with higher accuracy by utilizing this a posteriori error estimate. Finally, several numerical experiments are considered to confirm the theoretical results and compare the performance of the proposed methods.