OPTIMUM DESIGN OF COMPOUND CYLINDERS WITH SINTERED CARBIDE INNER LINER UNDER ULTRAHIGH PRESSURE

An optimum design approach is presented to improve the strength of compound vessels with sintered carbide inner liner under ultrahigh pressure. The design is based on equal-strength principle in this investigation; the wall ratio (ratio of outer to inner radii) of each outer layer is selected as design variable. With fixed total wall ratio, the optimization model with maximum elastic pressure capacity is built. Lagrange multipliers method is used to obtain the optimal design formula of wall ratio of each layer and the formula of maximum inner pressure, from which the optimum exact solutions of shrinkage pressure and radial interference are derived using the superposition principle. The practical example has proved that the compound vessels with sintered carbide inner liner require the larger shrinkage pressure than the compound vessel without the liner. For the three-layer compound vessel, the middle layer and inner liner resist radial compressive stress mainly, whereas the outer layer resists hoop tensile stress mainly.