Error estimation for natural frequency finite element analysis

The eigenvalue obtained from a finite element analysis of structures to estimate the buckling load factor or natural frequency has been improved by the use of a least-squares interpolation over a patch of elements. The eigenvalue improvement technique is based on the refinement of the finite element model and using the original eigenvector. The method presented in this paper involves solving a set of simultaneous equations for each patch of elements. These equations are based upon the equations of motion of the finite element model as oppposed to a relative simple smoothing function used in the least-squares interpolation procedure.