In this paper the theoretical validity of the equivalent homogeneous model for materials perforated with circular holes arranged in a square pattern is demonstrated. The two sets of effective elastic constants for loading in the pitch and diagonal directions, respectively, are related so that there are actually only three independent effective elastic constants. The six effective elastic constants for loading in any arbitrary direction are obtained from the known values for loading in the pitch direction.

The second part of the paper is concerned with the solution for the equivalent anisotropic circular plate with simply supported edges subjected to uniform pressure. There is no closed form solution to this problem. A doubly infinite complex series solution has been published by Okubo. The error incurred by truncating that solution after the first complex term of each series is shown to be small. This solution is satisfactory for design calculations over the entire range of ligament efficiencies greater than 5%.