[c1118]

Hello, I've modeled a straight pipe that is made from a mix of elbow elements and shell elements (elbow section-shell section-elbow section) under a constant internal pressure of 20 MPa. Because Abaqus assumes a closed-end condition for ELBOW elements I applied a compensating point load at the open ends of the elbow section (F=P*(pi*Din^2)/4). Also I applied kinematic coupling constraints between the elbow and the shell section and added a BC: UR3=0.
The BCs for the whole model are: U1=U2=U3=0 on one end and U1=U2=0 on the other.
I am not sure what I did wrong but the result I got isn't what I expected. I am assuming that the pipe should just expand under internal pressure but as you can see in the picture attached there is some deformation at the points where the elbow section connects with the shell section.
Any help on what I could do to solve this would be greatly appreciated, thank you!