Static and dynamic analysis of toroidal LPG tanks

Abstract

Liquefied petroleum gas (LPG) is considered clean, safe and cheap, offering a viable alternative to conventional fuels. Nowadays, the use of LPG as a fuel source in motor vehicles is steadily increasing. The LPG tanks in motor vehicles can be of toroidal shape. The toroidal LPG tanks are generally of non-circular cross-section, and may be supported at points, lines or patches on the surface. Among the mechanical properties of interest for toroidal LPG tanks are the static behavior under internal pressure, the vibration characteristics, the buckling and collapse loads, and the properties under impact loading arising from accident conditions. In the current work, a shell-theory finite element analysis is carried out of toroidal LPG tanks, with non-circular cross-section. The analysis serves to determine the natural frequencies, the buckling and collapse pressures, and the deformation of impacted tanks. The differential quadrature method is used as an alternate means in the vibration analysis. A variety of support conditions are considered, including lines of support at the inner and outer equators of the tank. For validation, comparison is made with previously published results for stress, vibration and buckling of circular and elliptical toroidal shells, and impact deformation of spherical and cylindrical shells. Finally, a parametric study is carried out to determine the influence on the natural frequency, buckling and collapse pressures, and the deformation of the impacted tanks, of shell size, shell thickness, material properties, and support conditions.