The Effect of Stick Stiffness of Friction Models on the Bending Behavior in Non-Bonded Flexible Risers

This paper investigates the effect of stick stiffness on the bending behavior in non-bonded flexible risers. The stick stiffness was normally implemented in the friction model for calculating the friction stress between layers in such structures. As the stick stiffness may be too small to achieve the plane-surfaces-remain-plane assumption under low contact pressure in some friction models [1], a new friction model was proposed for maintaining the constant stick stiffness in the present work. Less stick stiffness than that obtained by the plane-surfaces-remain-plane assumption was observed in test data. It was assumed that the stick stiffness reduction is caused by shear deformation of plastic layers. A numerical study on stick stiffness by including the shear deformation effect was carried out and verified against full scale tests with respect to the bending moment-curvature relationship.