The design of twin-saddle supported multi-layered glass-reinforced plastic vessels—the development of a parametric equation for the maximum strain

Abstract

The maximum strain in a glass-reinforced plastic vessel, supported on rigid saddle supports, invariably occurs at the uppermost point of the support known as the saddle horn. The strain, which is in the circumferential direction, is compressive on the outside and tensile on the inside surfaces of the vessel. This can create problems in composite vessels since local cracking of the inner surface may allow liquid ingress to the glass through the matrix, with premature local failure by stress corrosion cracking. The analysis of this support problem has been solved using a double Fourier series by Tooth et al, [8], by which the maximum strain in the support region can be derived. The present paper presents a parametric study for an extensive range of vessels, in use in the process and chemical industries, using this analysis. To aid the design process the results for the crucial maximum strain values are presented in a ‘closed form’, using an equation-fitting technique. The details of the procedure used to achieve these equations should be of interest to analysts in other fields of work. Typical examples are given to illustrate the use of the derived equations for a symmetric laminate.