J Lahde

Pipe bending simulation

Discussion created by J Lahde on Dec 11, 2020
Latest reply on Dec 14, 2020 by Shawn Mahaney


I'd like to ask regarding pipe bending situation where there is also a inner pressure applied.


I have a DN1000 pipe with wall thickness of 11mm. It has a inner pressure of 2,5MPa and the bending moment(using distributed load) affecting at the end of the pipe is 878,8kNm. The inside pressure will cause a tensile force of 1943kN and that is placed on the end of the pipe. 


The constraints are so that x-axis is symmetrically constrained, while the top and bottom are constrained in Z-radius and the points on the both sides are constrained in Y-radius.


When there is a bending moment, the stresses should be equal on top and bottom(tension and compression) sides, right? After adding the pressure the tension side(top) should have higher stresses due to the tensile force!?


The results should have a stresses where the top of the pipe(tension side) has higher stresses and the bottom(compression side) has lower stresses. However, this does not happen, instead I get equal stresses on both sides. 


If I test it without the tensile force modelled, the stresses differ on the top and bottom, but the compression side has higher stress??



What am I doing wrong in this simulation set up? How am I supposed to model both bending and pressure on the same occasion?