Principal displacements in a pressurized elliptic cylinder: Theoretical predictions with experimental verification by laser interferometry

Abstract

Equations for principal displacements in a uniformly pressurized thin-walled cylinder having an elliptic median line are developed from a knowledge of the expressions for tension and bending moment (1) at a general position in the cylinder wall. Displacements derived from these equations are compared with the simple expressions presented by Bresse (2) and MacAlpine (3). The results of a detailed experimental study in which displacements were measured by a laser interferometer are used to assess the validity of the new displacement equations and to compare these with the predictions due to Bresse and MacAlpine. It is shown that the equations developed here give good agreement with experimentally measured displacements and furthermore the predictions made in (2) and (3) grossly overestimate the displacement values and are also very much in error when stating that the minor-diameter expansion is of the same order as the major-diameter contraction. In the investigation reported here (ellipse with mean aspect ratio 1.9509) the expansion of the minor diameter is approximately twice the value obtained for the contraction of the major diameter.