液体火箭发动机用小直径管路焊接疲劳分析方法研究

Fatigue Analysis of Small-Diameter Welded Pipe in Liquid Rocket Engine

关键词:  随机振动  振动疲劳  焊接疲劳  结构应力  小直径管路

Key words:  Random vibration  Vibration fatigue  Welding fatigue  Structural stress  Small-diameter pipeline

摘要:

为了简化焊接圆管的随机振动疲劳计算，通过理论推导和仿真对比证明了焊接疲劳分析中“结构应力法”所指的结构应力实质同材料力学计算的名义应力是一致的，并以此提出了一种快速开展设计和分析的简化方法，不依赖于FE-Safe软件，且发挥了梁单元模型的效率优势。另外，基于梁单元模型的随机振动计算结果对减震卡箍多方案布置对结构焊接疲劳寿命的影响展开讨论，认为卡箍分散布置和增加数量虽然可以有效避开结构共振频率，然而并不一定会提高焊接疲劳寿命，甚至可能会加速焊接位置的失效，具体布置设计需要结合疲劳计算结果。

Abstract:

In order to simplify the calculation of random vibration fatigue of welded pipe， this paper proves that the structural stress referred to by structural stress method in welding fatigue analysis is consistent with the nominal stress calculated by material mechanics， and a simplified method for rapid design and fatigue analysis is proposed， which is not only independent of FE-Safe software，but also takes advantage of the efficiency of beam element model. In addition， based on the random vibration calculation results of the beam element model， the effects of the multi-scheme arrangement of damping clamps on the welding fatigue life of the structure are discussed. It is considered that the scattered clamps and the increased number can effectively avoid the resonance frequency of the structure， but it does not necessarily improve the fatigue life of the welding， and may even accelerate the failure of the welding position. The specific layout design needs to combine the fatigue calculation results.