Abstract: When a corrugation structure is located in the bottom of original spherical-dished diaphragms, expulsion efficiency is low. In order to heighten the expulsion efficiency of diaphragms, a corrugation structure is located near a dished section. The buckling and post-buckling equilibrium configurations of original and modified diaphragms are numerically analyzed by the finite element method (FEM). By the comparison of research results about the two diaphragms, the conclusions are as follows: modified diaphragms are better for expulsion than the original ones, and the former has higher expulsion efficiency; severe eccentricity and folding problems, which are likely to cause fracture failure of the original diaphragms, do not happen in the modified ones; the maximum Von Mises stresses of modified diaphragms are much smaller than that of original ones, which indicates modified diaphragms are less probable to reach the limit stress of the material during an expulsion process.