不等厚性对弯头应力分布影响的有限元研究

Influence of the non-uniform thickness elbow on the stress distribution by FEA method

弯头作为受压管道中的重要部件,不仅能改变管线的方向,还可以提高管路柔性,缓解管道振动和约束力,并对热膨胀起补偿作用。以往对弯头的研究只考虑壁厚均匀不变的情况,但是实际上弯头的壁厚是沿着弯曲半径变化的,并且弯头的截面也具有一定的椭圆度。通过对实际生产中弯头壁厚的调研,分别考察热推、冷弯工艺对弯头壁厚改变的影响。并应用有限元方法分析了冷弯弯头的应力状况,得出其最大应力发生点随着外拱处壁厚减薄量的增大而向外拱处转移。

Changing the pipeline direction, improving the flexibility, reducing the vibration, releasing the stress and compensating the thermal expansion can be achieved by the elbow, which is the important part of pressure piping system. In the previous works only the uniform wall-thickness elbows were studied. However, the elbow thickness is varied with the bending radius and eUipticity on the cross section. In the investigation of wall-thickness formed in the actual manufacture process, the variation of thickness in hot-bending and cold-bending were compared. The resuhs of FEA method for cold-bending elbow predicted that the point of maximum stress is transferred from intrados to extrados with the increase of the wall thinning.