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

The maximum strain in a glass-reinforced plastic vessel, supported on rigid saddle supports, invariably occurs at the uppermost point of the support k nown as the saddle horn. The strain, which is in the circumferential direct ion, is compressive on the outside and tensile on the inside surfaces of th e vessel. This can create problems in composite vessels since local crackin g of the inner surface may allow Liquid ingress to the glass through the ma trix, with premature local failure by stress corrosion cracking. The analys is 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 ra nge of vessels, in use in the process and chemical industries, using this a nalysis. To aid the design process the results for the crucial maximum stra in values are presented in a 'closed form', using an equation-fitting techn ique. The details of the procedure used to achieve these equations should b e of interest to analysts in other fields of work. Typical examples are giv en to illustrate the use of the derived equations for a symmetric laminate.