Description:
Toroidal shells as pressure vessel have been used as LPG storage tanks for passenger cars. Current practice places the toroidal LPG tank on the position of spare wheel of a passenger car. In addition to its easy in installation on a car, toroidal tanks have higher limit pressure than an equivalent cylindrical tanks for certain values of radius ratio. In practice, designer has to decide whether choosing circular or oval cross-section. Oval cross-section can be chosen either in-plane or out-ofplane
oval. In-plane oval cross section has major axis from extrados to intrados, whereas, out-ofplane oval has major axis of cross-section from crown to crown. This paper reports a finite element study of the nonlinear behaviour of in-plane and out-of-plane oval toroidal shell under internal pressure. The ANSYS shell element has been used in finite element modeling. The material properties were assumed to be elastic-perfectly plastic. Limit pressure was obtained via the wellknown Newton-Raphson algorithm for nonlinear analysis. Radial displacement of nodes in the position of extrados, 450 from extrados, crown, 1350 from extrados, and intrados were reviewed. The results show that the load – displacement relation is linear for toroidal circular both in elastic and plastic state indicated the membrane dominant behavior. Very significant nonlinearity occurs for both in-plane and out-of-plane oval cross-section, believe to be due to shell bending. The overall results show that toroidal shells of circular cross-section have higher limit pressure than those of oval cross-section. Volume expansion of toroidal shell of circular cross-section due to internal pressure dominated by membrane behavior, while for oval cross-section, bending behavior contributes. It is interesting to note that limit pressure of toroidal shell having out-of-plane oval
cross-section is higher than those of in-plane oval.
Keywords: toroidal shells, in-plane oval, out-of-plane oval, nonlinerity, membrane, shell bending, finite element