超深水水下分离器嵌入式接管马鞍形焊缝应力集中系数分布规律研究

Study on the distribution of stress concentration factor along the saddle-shape weld toe of embedded nozzles on ultra-deepwater subsea separators

针对超深水水下分离器接管焊缝应力集中问题,考虑深水高外压载荷工况,引入子模型技术,提出了嵌入式接管焊接结构分析方法,基于路径映射技术研究了水下分离器样机马鞍形焊缝焊趾处的应力集中系数分布规律,并分析了切割孔半径、焊趾倾角和焊趾过渡圆弧半径等3个几何参数对马鞍形焊缝焊趾应力集中系数分布的影响,结果表明:水下分离器样机不同接管焊趾应力集中系数分布不同,接管位置对焊趾应力集中系数分布没有影响;切割孔半径决定焊趾应力集中系数分布形式,减小焊趾倾角,增加焊趾过渡圆弧半径能够改善焊趾处的应力集中,但焊趾过渡圆弧半径作用有限。以所研究的水下分离器样机为对象,设计了高压舱实验,制定了测点贴片方案,捕捉到了接管焊趾处应力集中系数分布特征点,而且数值分析结果与实验结果吻合较好,表明本文构建的数值模型具有较高精度,可为嵌入式接管结构设计提供参考。

Aiming at the problem of stress concentration in nozzle welding on ultra-deepwater subsea separa- tors, an analysis method for structures with embedded nozzle welding under high external pressure was proposed by virtue of submodel technology. Stress concentration factor distribution along the saddle-shape weld toe on subsea separator prototypes was explored using path mapping technology. The impact of geo- metric parameters such as cut-hole radius, weld bead angle and weld toe radius on the stress concentration factor distribution along the weld toe was analyzed. Research results indicate that the stress concentration factor distribution along the weld toe is different with different nozzles, but the position of nozzles has no effect on the distribution. The form of stress concentration factor distribution is determined by the cut-hole radius. Stress concentration can be mitigated by reducing weld bead angle and increasing weld toe radius,but the latter has only limited effect. Utilizing the subsea separator prototype, a hyperbaric chamber ex- periment was designed and the strain gages was laid out. Moreover, the characteristics of stress concentra- tion factor distribution along the weld toe were captured. The numerical calculation results were in fair a- greement with the test results, showing that the numerical model is accurate, which can provide reference for the structure design of embedded nozzles.