Abstract: In this paper in the terms of theory we have proved that the reciprocal theorem is equivalent to the superposition principle of displacements and is equivalent to the superposition principle of reactive forces. These equivalents have important theoretical values and practical values. At the same time we also point out that Castigliano's displacement equation can be applied to solve the interior displacement of the region of the deformable body too.

Key words: corrugated diaphragm, large boundary corrugation, nonlinear bending, elastic characteristic, annular plate