Numerical simulation was carried out on the end structure of the ultrahigh pressure polyethylene tubular reactor in which fatigue fracture occurred based on the finite element program-ANSYS. The local stress field of the reactor was analyzed after its shrink - fit, autofrettage treatment and under the on - service startup and shutdown cyclic loading. The results show that axial tensile stress is high on the location at the edge of the shrink - fit under the shrink - fit and the startup and shutdown cyclic loading,and it's larger than hoop stress; The local axial stress increases with the increase of shrink range and autofrettage stress;The reactor with 0.05 mm shrink range are analyzed,the maximal local axial mean stress is 86.71 MPa,the maximal local axial alternating stress amplitude is 62. 2 MPa, which indicates that the crack driving force perpendicular to the axial direction is relative larger. The simulated results can provide some insight into the reason of failure and the improvement of the end structure.%基于大型通用有限元软件ANSYS,对发生疲劳断裂的超高压管式反应器的端部结构进行数值模拟,分析了其在过盈套合、自增强处理以及服役期间开停工循环载荷三种工况下的局部应力场.结果表明:三种工况下,端部结构在过盈套合边缘局部范围内均存在较高的轴向拉应力,且大于环向应力；局部轴向应力随套合过盈量和自增强压力的增加而增大；半径过盈量为0.05 mm时,开停工循环载荷下的局部轴向平均应力最大值可达86.71 MPa,轴向交变应力幅值最大值达到62.2 MPa,裂纹垂直于轴向扩展的推动力较大.模拟分析结果对端部结构失效破坏原因的分析及其设计改进有一定的指导意义.
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