Moorpy-Tension along segments

[kala-j-prasad]

Hello,
Iam using Moorpy for static analysis of catenary mooring line .
Iam trying to get the segment wise axial forces , but facing errors.
Iam able to get the axial tension at the fairlead and anchor point, but not at the other segments.
It will helpful if i could know how to do it ?

import moorpy as mp
import numpy as np

1. Create the system object

ms = mp.System(depth=200)
print("System created")

2. Define Line Type

ms.setLineType(dnommm=185, material=None, source=None, name="chain", mass=685, d_vol=0.333, w=None, EA=3.27e9, lineType=None,
overwrite=True)

print("Line type added")

3. Add anchor point (fixed)

ms.addPoint(mytype=1, r=[-837.6, 0, -200])
print("Anchor point added")

4. Add fairlead point (fixed directly)

ms.addPoint(mytype=1, r=[-58, 0, -14],body=0)
print("Fairlead point added (fixed)")

5. Add mooring line

ms.addLine(lUnstr=850, lineType='chain', nSegs=50, pointA=1, pointB=2)
print("Line added")

6. Initialize and solve

ms.initialize()
ms.solveEquilibrium()
print("Equilibrium solved")

#######################################################################################################################

7. Get the line object

line = ms.lineList[0]

8. Print tensions

print("Tension at anchor end (TA):", (line.TA/1000).round(), "kN")
print("Tension at fairlead end (TB):", (line.TB/1000).round(), "kN")
#####################################################################################

9. Get line coordinates

coords = line.getLineCoords(0)

X = coords[0]
Y = coords[1]
Z = coords[2]

10. Print coordinates

print("\nLine coordinates (x, y, z):")
for i in range(len(X)):
print(f"{i}: ({X[i]:.2f}, {Y[i]:.2f}, {Z[i]:.2f})")

[mattEhall]

Hi @kala-j-prasad,

I believe getLineCoords will actually return a four lists
Xs, Ys,Zs, Ts = line.getLineCoords(0)
where Ts is the tensions along the line.

Alternatively, you can access the tensions along the line using line.Ts.

Cheers,
Matt

[kala-j-prasad]

Hello @mattEhall ,

Yes that worked.

I have another query
Iam trying to perform a Static surge sway analysis, ie. trying to get the tensions in the line when the platform have a displacement in surge sway side.
Is it possible to perform using moorpy ?

Thanks

[kala-j-prasad]

Hello,

Iam trying to attach the fairlead point to the body, But iam not able to attach it,
Is this the right way to code it ?Sharing the part of the code

Add floating platform body

ms.addBody(0, [0, 0, 0,0,0,0], m=m_plat, v=displaced_vol, rM=rM_roll, AWP=AWP)

======================

LINE TYPE (Chain)

======================

ms.setLineType(dnommm=185, mass=685, d_vol=0.333, EA=3.27e9, name="chain", overwrite=True)

======================

ANCHOR POINT (fixed)

======================

anchor_pos = [-837.6, 0, -seabed]
ms.addPoint(mytype=1, r=anchor_pos)

======================

FAIRLEAD POINT (on platform)

======================

fairlead_pos = [-58, 0, -14]
ms.addPoint(mytype=1, r=fairlead_pos)

======================

MOORING LINE

======================

line_length = 850
n_segments = 50
ms.addLine(lUnstr=line_length, lineType="chain", nSegs=n_segments, pointA=1, pointB=2)

======================

Attach fairlead to platform body

ms.bodyList[0].attachPoint(2, fairlead_pos)

======================

SOLVE EQUILIBRIUM

======================

print("\nSolving for static equilibrium...")
ms.initialize()
ms.solveEquilibrium()
print("Equilibrium solved successfully!")