﻿ PipeLay > Software Components & Operation > Defining a Line > Line Subcomponents > Flex Joint > Flex Joint Data Inputs

Flex Joint Data Inputs

 Input Description Type: A drop-down list which allows you to select the type of flex joint. The options are Linear (the default) and Non-Linear. Curve: A drop-down list which allows you to select Manual or Automatic non-linear Moment Angle curves. Properties: Click on this button to display the Linear Properties – Define or Non-Linear Properties – Define dialog. See the ‘Linear or Non-Linear Properties Dialog’ section for a detailed description of this dialog. Moment Angle Curves Click on this button to display the Moment/Angle Curves – Define dialog. See the ‘Moment/Angle Curves – Define Dialog’ section for a detailed description of this dialog. This button is only available for Manual non-linear flex joints. Rotation Angles: Click on this button to display the Automatic Moment/Angles Curves dialog. See ‘Automatic Moment/Angle Curves – Define Dialog’ section for a detailed description of this dialog. This button is only available for Automatic non-linear flex joints.

Linear or Non-Linear Properties Dialog

 Input Description Length: The length of the flex joint. Units: [m] or [ft] Rotational Stiffness: The rotational stiffness of the joint. This value is mandatory for linear flex joints and is not relevant for non-linear flex joints. Units: [kNm/deg] or [kips.ft/deg] Weight in Air: The weight in air of the flex joint. Units: [kN] or [kips] Weight in Water: The weight in water of the flex joint. Units: [kN] or [kips]

Moment/Angle Curves – Define Dialog

 Input Description Moment: A moment value for a point on the curve. Units: [kNm] or [kips.ft] See Note (a) - (c) Angle: The corresponding angle value. Units: [deg]

Notes:

(a)The points defining the non-linear moment-angle curve may be specified in any order. PipeLay subsequently sorts the data pairs into ascending order of angle.

(b)If the rotation of the non-linear flex joint lies between the specified moment-angle data points, PipeLay uses linear interpolation to determine the relevant rotational stiffness of the element.

(c)If the rotation of the non-linear flex joint lies outside the specified range of the moment-angle curve, then PipeLay simply extrapolates from the first or last section of the curve as appropriate.

Automatic Moment/Angle Curves – Define Dialog

 Input Description Positive Free Rotation Angle: The free rotation angle for the flex joint measured as a positive rotation to be consistent with a right-handed axis system. Units: [deg] See Note (a) Negative Free Rotation Angle: The free rotation angle for the flex joint measured as a negative rotation to be consistent with a right-handed axis system. Units: [deg] See Note (b)

Notes:

a)The right-handed axis system is determined by the orientation of the Line component or the Articulated Stinger component that contains this flex joint.

b)A non-linear flex joint moment angle curve can be automatically calculated by defining limiting positive and negative free rotation angles. The User Interface uses the Inverse Boltzmann function to compute the moment angle curvature between these two angles.