07. When modeling a flexible hose, what is the most realistic way to model the curved flex hose in A

Applies To
Version(s):2004, XM, & V8i
Area: Modeling
Original Author:Bentley Technical Support Group

Dec 2014, AutoPIPE V8i


When modeling a flexible hose, what is the most realistic way to model the curved flex hose. Using 1 flex joint, 2 flex joints or many flex joints?


Keep in mind what a flexible hose is doing, as mentioned above "it is like a break in the pipe with no transfer of force or moments". Therefore you can model it using a single flexible joint or using multiple flexible joints where both approaches would use very low Axial, Bending, and Shear stiffness values. 

Assuming the stiffness values used are very low, then both modeling approaches would be valid. The only major difference between them would be the CG location of the hose. Depending on the hose size, it may need to be considered. Thus giving a slight edge to using multiple flexible joints when modeling a hose (assuming you know the exact path of the flexible hose during operating load cases).

1. When inserting a flexible joint be aware of the stiffness directions and how that affects the connected pipe. Example, using a single flexible joint, axial stiffness is acting along the line of the connected points. Using low values as mentioned above, should not affect the results very much. However, if for what ever reasons axial stiffnesses are higher, it could affect how the connect pipe moves during load case combinations.

2. If modeling multiple flexible joints back to back. Consider adding a short bend pipe between the joints to reduce the occurrence of warnings (i.e. W726-8:  Kink in straight run ...).


See Also

Flexible Joint - Modeling Approaches, Tips, Techniques

Bentley AutoPIPE