| name | fe-analyst-1-fea-fundamentals-for-slender-structures |
| description | Sub-skill of fe-analyst: 1. FEA Fundamentals for Slender Structures. |
| version | 1.0.0 |
| category | engineering |
| type | reference |
| scripts_exempt | true |
1. FEA Fundamentals for Slender Structures
1. FEA Fundamentals for Slender Structures
OrcaFlex models slender structures (pipes, lines, cables) as Euler-Bernoulli beam elements with:
| DOF per node | Description |
|---|
| u, v, w | Translational (surge, sway, heave) |
| θx, θy, θz | Rotational (roll, pitch, yaw) |
Element stiffness contributions:
- Axial stiffness:
EA (axial force vs. extension)
- Bending stiffness:
EI (moment vs. curvature)
- Torsional stiffness:
GJ (torque vs. twist)
- Shear stiffness: optional (Timoshenko)
Key non-linearities in slender structure FEA:
- Geometric non-linearity (large displacements, catenary shape)
- Contact non-linearity (seabed, bend stiffeners, clamps)
- Material non-linearity (yield — typically not modelled for fatigue)
- Hydrodynamic drag non-linearity (Morison equation, velocity-squared)