A Theoretical and Experimental Study on Extreme Stress Concentration-Free Designs of Circumferentially Notched Thin Cylindrical Shells
A Theoretical and Experimental Study on Extreme Stress Concentration-Free Designs of Circumferentially Notched Thin Cylindrical Shells
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DOI：
10.1115/1.4045281
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发表时间：
2020-02-01
影响因子：
2.6
通讯作者：
Li, Rui
中科院分区：
文献类型：
--
作者：
Shi, Yunfeng;Wang, Bo;Li, Rui
如何保证具有周向缺口的薄圆柱壳具有足够的轴向承载能力和径向易损性，是航天分离装置等关键结构设计的主要难题之一。这种髋臼杯最有利的设计是优化切口几何形状，以便在切口根部实现零应力，这提高了轴向强度，而不会在分离期间影响切口失效。然而，由于普通偏心荷载作用下的非对称结构给理论分析带来了很大困难，而数值方法又难以满足高效快速优化设计的要求，因此，对于单边切口壳体这种无极端应力集中设计的研究还很少。本文对单边切口圆柱薄壳的无极限应力集中设计进行了理论和实验研究。基于缺口应力理论，得到了任意深度单边缺口的广义应力集中系数，并通过有限元精细建模进行了验证。一个重要的发现表明，对于航空航天器中常见的缺口壳体，当载荷偏心率与最小截面宽度之比达到一定值时，缺口根部的应力趋于零。专门设计的缺口试样的综合实验证实了理论发现。本文的研究为分析单边切口结构提供了一种有效的方法，并为周向切口圆柱薄壳的优化设计提供了一个明确的定量指导。
To ensure both adequate axial load-bearing capacity and radial vulnerability of a circumferentially notched thin cylindrical shell is one of the major challenges in designing some crucial aerospace structures such as the pyrotechnic separation devices. The most favorable design for such a shell is to optimize the notch geometry such that zero stress at the notch root is realized, which enhances the axial strength without impacting the notch failure during separation. However, few studies have focused on such extreme stress concentration-free designs of a single-side notch on a shell because the asymmetrical structure under common eccentric loading brings much difficulty for theoretical analysis, while numerical approaches can hardly meet the requirements of highly efficient rapid optimal designs. In this paper, a theoretical and experimental study toward extreme stress concentration-free designs of single-side-notched thin cylindrical shells is presented. The general stress concentration factors (SCFs) for single-side notches with arbitrary depths are obtained based on the theory of notch stresses, which are well validated by the refined finite element modeling. An important finding reveals that, for a common notched shell in aerospace vehicles, the stress at the notch root approaches zero when a specific ratio of load eccentricity to minimum section width is attained. Comprehensive experiments for specially designed notched specimens confirm the theoretical finding. The present study provides an effective approach to analyzing single-side-notched structures and yields an explicit quantitative guideline for the optimal design of circumferentially notched thin cylindrical shells.