Error estimates for isoparametric mixed finite element solution of 4th order elliptic problems with variable coefficients

Considering the combined effect of boundary approximation and numerical integration, error estimates for the isoparametric mixed finite element solution of fourth order elliptic problems with variable coefficients in convex domains, which, in the particular case of aniso-/ ortho-/ isotropic plate bending problems, gives a direct and simultaneous approximation to bending moment tensor field Psi = (psi(ij))(1less than or equal toi,jless than or equal to2) and displacement field 'u', have been developed. Results of numerical experiments justify the theoretical results.