BFLEX2010

Q: What are the proper ICODE values to use for a carcass geometry?

A: The carcass model does not use the ICODE specifications directly. However, the user must supply 2 separate segments with ICODE 2. The rest should be 0.

Q: Can I use ccode manual in a flexcross crossection for carcass or pressure spiral if I plan to process the model using BOUNDARY and PFLEX?

A: No, you must describe the geometry using CROSSGEOM BFLEX

Q: Is it important where the origin of the curve is positioned when I describe a closed profile, such as the geometry of the pressure armour layer?

A: No, BFLEX will in calculate area center and place the geometry accordingly. BOUNDARY/PFLEX however have some limitations. For a zeta profile, the first segment issued with ICODE=1 should always be the inner contact surface. Further, z0=0 in the CROSSGEOM implies that the geometry definition is starting at the outer surface. It is hence adviced to start the definition in the uppper left corner of the profile and proceed to the inner contact surface, ending with the outer contact surface. Otherwise the radial offset of the starting point must be specified in the z0 parameter, typically with a negative value.

Q: I have noticed that if the thickness of the flexlok profile in the crossgeometry card and the the flexcross card differs, the software runs anyway. How are the thicknesses related?

A: For the BFLEX2010 step of the analysis, the geometry of the crossgeom curve is used for establishing areas, stiffnesses etc. The thickness will be according the to flexcross card and the radial position of the layer will be using that information.

When proceeding to the BOUNDARY step, contact from the neighbouring layers is applied as a contact pressure and hence inconsistence in thickness it not a problem for that part of the contact. However, the nub/valley contact are using the geometry from the curve to find contact. Profiles of type CCLI for example, may in this case start with large contact forces if the geometries are positioned such that they overlap. Or in the oposite case missing contacts/too large gaps.

Q: Can I obtain the slip curvature as a result for a FLEXCROSS model?

A: The shape of the moment-curvature curve is reported to the *.blf file at time TIMEINI.

Q: I have a torsionally unbalanced cross section and the load sharing between the tensile armour layers are not as expected?

A: The FLEXCROSS model was established under the assumption of a fairly torsion balanced cross section. If this is not the case it is better apply the 353FLEXCROSS model. For FLEXCROSS the procedure for distributing the axial load sharing/axial stress due to tension and pressure is defined under the assumption of zero moment in torsion. For that reason the consistency of the analysis is maintained if dof 4 is fixed in the analysis. So strictly speaking, dof 4 should always be fixed in a FLEXCROSS model. However, the results will actually be closer to what you would obtain for a torsion free case.

The 353FLEXCROSS model does not have this limitation. It can represent both torsion free/fixed for balanced/unbalanced pipes.