内压作用下发动机反向封头屈曲参数化研究

PARAMETRIC BUCKLING DESIGN STUDIES OF ROCKET MOTOR INVERTED BULKHEADS UNDER INTERNAL PRESSURE

内压作用下发动机反向封头的稳定性是设计中的考虑重点。采用轴对称有限元方法对不同设计参数的等厚度和变厚度两大类反向封头进行稳定性研究,模型考虑封头开口加强环及封头与圆柱段连接处的局部加强影响。参数化研究椭球比、壁厚对封头临界屈曲载荷的影响。研究结果表明,等厚度反向封头的外形和变厚度的壁厚对结构临界屈曲载荷的影响十分敏感,在最小厚度一定的情况下,椭球比为1.413的变厚度封头是最小质量设计。另外文中给出可供工程实际设计参考的图表及曲线。

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.