压力容器含裂纹接管过渡区有限元分析及优化

Finite Element Analysis and Optimization of Transition Zone of Pressure Vessel with Cracked Pipes

针对压力容器服役过程中因应力集中而形成裂纹的问题,运用有限元软件仿真计算压力容器接管过渡区裂纹尖端应力强度因子和最大等效应力。通过改变接管尺寸、焊接不同厚度补强圈或翅片,比较其对Ⅰ型应力强度因子KI及最大等效应力的影响。结果表明,增大接管壁厚和内、外过渡圆角直径,减小接管开孔尺寸,焊接补强圈或翅片均可一定程度上减小KI及最大等效应力;增大内过渡圆角直径的效果较增大外过渡圆角直径的效果更好;补强圈与筒体厚度比存在最佳值,厚度比为0.35时KI及最大等效应力最小;焊接翅片可有效降低KI及最大等效应力。

Aiming at the problem that cracks are often formed due to stress concentration during the service of pressure vessels,finite element software was used to simulate and calculate the stress intensity factor and maximum equivalent stress of the crack front node.By changing the size of the connecting pipe,welding reinforcing rings of different thicknesses,or installing fins,the effects on the type I stress intensity factor KI and the maximum equivalent stress were compared.The results show that increasing the wall thickness of the connecting pipe,increasing the diameter of the inner and outer transition fillets,reducing the size of the opening,and welding the reinforcing ring or fins can reduce the stress intensity factor KI and the maximum equivalent stress to a certain extent;the effect of increasing the diameter of the inner transition fillet is better than increasing the diameter of the outer fillet;there is an optimal value for the thickness ratio of the reinforcing ring to the cylinder,the KI and the maximum equivalent stress are the smallest when the ratio of the thickness of the reinforcing ring to the cylinder is 0.35;the selecting of an appropriate finned tube size can effectively reduce KI and maximum equivalent stress.