Parametric buckling design studies of rocket motor inverted bulkheads under internal pressure

Buckling stability is critical consideration factor during design of inverted bulkheads under internal pressure. Total 30 bulkheads with different design parameters that had an inverted, oblate geometry subjected to internal pressure-only loading were investigated. Thicknesses of bulkhead walls and bulkhead geometry shape were chosen as design parameters. Buckling characterization was present for both equal thickness and variable thickness bulkhead using axisymmetric finite element method (FEM). The effects of stiffening support ring and local thickness increasing at the bulkhead to cylinder interface were considered. Linear buckling eigenvalue analyses were implemented to get critical buckling loads and buckling modes. Results show that the buckling characterization of an equal-thickness inverted bulkheads require careful attention as small changes in shape parameters can have a significant effect to critical buckling load. Whereas thickness of wall is the most critical parameter to variation thickness bulkheads. Combining the mass characterization consideration, the minimum mass design can be obtained when the ellipse ratio is 1.413 for these bulkheads. Research conclusions may have some value in guiding engineering inverted bulkheads designs.