Asymmetric FPSO Roll Response due to the Influence of Lines Arrangement

2012 ◽  
Author(s):  
Marcos Donato Ferreira ◽  
Mauro Costa de Oliveira ◽  
Rafaella Cristina Carvalho ◽  
Sergio Hamilton Sphaier
Keyword(s):  
Integration Scheme ◽  
Impulse Response Functions ◽  
Viscous Effects ◽  
Lumped Mass ◽  
Explicit Integration ◽  
Deep Waters ◽  
Campos Basin ◽  
Motion Responses ◽  
Non Linear ◽  
Ship Hydrodynamic

In the development of the mooring design of FPSOs in spread mooring system (SMS) configuration, it was observed that the utilization of asymmetric riser arrangement in deep waters might lead to an asymmetrical roll response of the FPSO. In particular, concentrating all riser connections on the portside, it could be observed that roll and heave coupling under the influence of the riser dynamics might lead to a much lower roll response associated with waves coming from portside than from the starboard direction. Simulations were carried using an in-house time domain simulator, where the ship hydrodynamic behavior was represented through the use of impulse response functions and the lines dynamic through the use of non-linear finite element method, using an explicit integration scheme and a lumped mass approach. Non-linear viscous effects could be easily associated to the ship and line velocities. Measured motion responses of an actual FPSO in operation in Campos Basin are compared with the computations.

The Anchor-Last Deployment Problem for Inextensible Mooring Lines

1975 ◽  
Vol 97 (3) ◽  
pp. 1046-1052 ◽  
Author(s):  
Robert C. Rupe ◽  
Robert W. Thresher
Keyword(s):  
Numerical Model ◽  
Equations Of Motion ◽  
Simultaneous Equations ◽  
Mooring Line ◽  
Integration Scheme ◽  
Lumped Mass ◽  
Mooring Lines ◽  
Concentrated Masses ◽  
Predictor Corrector ◽  
Lagrange’S Method

A lumped mass numerical model was developed which predicts the dynamic response of an inextensible mooring line during anchor-last deployment. The mooring line was modeled as a series of concentrated masses connected by massless inextensible links. A set of angles was used for displacement coordinates, and Lagrange’s Method was used to derive the equations of motion. The resulting formulation exhibited inertia coupling, which, for the predictor-corrector integration scheme used, required the solution of a set of linear simultaneous equations to determine the acceleration of each lumped mass. For the selected cases studied the results show that the maximum tension in the cable during deployment will not exceed twice the weight of the cable and anchor in water.

scholarly journals A new energy–momentum time integration scheme for non-linear thermo-mechanics

2020 ◽  
Vol 372 ◽  
pp. 113395 ◽  
Author(s):  
R. Ortigosa ◽  
A.J. Gil ◽  
J. Martínez-Frutos ◽  
M. Franke ◽  
J. Bonet
Keyword(s):  
Time Integration ◽  
Integration Scheme ◽  
Non Linear ◽  
New Energy ◽  
Time Integration Scheme

FROUDE’S LAW OF SIMILITUDE – CONTEMPORARY AND FUTURE SEAKEEPING TESTING

2021 ◽  
Vol 153 (A2) ◽  
Author(s):  
R P Dallinga ◽  
R H M Huijsmans
Keyword(s):  
Model Test ◽  
Scale Effects ◽  
Higher Order ◽  
Air Pressure ◽  
Test Results ◽  
Viscous Effects ◽  
Two Phase ◽  
Scale Models ◽  
Non Linear

Historically “scale effects” in the interpretation of tests with scale models in waves using Froude’s Law of Similitude are mostly associated with viscous effects. Nowadays, with a much more complete modelling of reality and a focus on higher order non-linear phenomena, scaling of model test results implies a wider range of assumptions than the validity of Froude’s Law. Our contribution to the conference is a visionary review of contemporary and future problems in the interpretation of these tests. In this context we will discuss the developments in test techniques, including the development of a new Two-Phase Laboratory facilitating seakeeping and sloshing tests at reduced air pressure.

Energy‐momentum consistent time integration scheme for non‐linear electro‐elastodynamics

PAMM ◽  
2018 ◽  
Vol 18 (1) ◽  
Author(s):  
Alexander Janz ◽  
Peter Betsch ◽  
Marlon Franke ◽  
Rogelio Ortigosa
Keyword(s):  
Time Integration ◽  
Integration Scheme ◽  
Non Linear ◽  
Time Integration Scheme

A thermodynamically consistent time integration scheme for non-linear thermo-electro-mechanics

2022 ◽  
Vol 389 ◽  
pp. 114298
Author(s):  
M. Franke ◽  
R. Ortigosa ◽  
J. Martínez-Frutos ◽  
A.J. Gil ◽  
P. Betsch
Keyword(s):  
Time Integration ◽  
Integration Scheme ◽  
Non Linear ◽  
Time Integration Scheme

An Efficient Response Analysis Method for a Non-Linear/Parameter Changing System Using Sub-Structure Modes

1993 ◽  
Vol 207 (1) ◽  
pp. 41-52
Author(s):  
H K Kim ◽  
Y-S Park
Keyword(s):  
Equations Of Motion ◽  
Forced Response ◽  
Suggested Method ◽  
Response Analysis ◽  
Synthesis Methods ◽  
Lumped Mass ◽  
State Equations ◽  
Mass Model ◽  
Non Linear ◽  
Forced Responses

An efficient state-space method is presented to determine time domain forced responses of a structure using the Lagrange multiplier based sub-structure technique. Compared with the conventional mode synthesis methods, the suggested method can be particularly effective for the forced response analysis of a structure subjected to parameter changes with time, such as a missile launch system, and/or having localized non-linearities, because this method does not need to construct the governing equations of the combined whole structure. Both the loaded interface free-free modes and free interface modes can be employed as the modal bases of each sub-structure. The sub-structure equations of motion are derived using Lagrange multipliers and recurrence discrete-time state equations based upon the concept of the state transition matrix are formulated for transient response analysis. The suggested method is tested with two example structures, a simple lumped mass model with a non-linear joint and an abruptly parameter changing structure. The test results show that the suggested method is very accurate and efficient in calculating forced responses and in comparing it with the direct numerical integration method.

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