Study on the Parametric Rolling of Medium-Sized Containership Based on Nonlinear Time Domain Analysis

2021 ◽  
Author(s):  
Seung Ho Yang
Keyword(s):  
Time Domain ◽  
Time Domain Analysis ◽  
Domain Analysis ◽  
Parametric Rolling ◽  
Nonlinear Time Domain

Nonlinear Time Domain Seismic Analysis for a Coupled Mooring Jacket-Yoke-FSO System

2009 ◽  
Author(s):  
Partha Chakrabarti
Keyword(s):  
Dynamic Analysis ◽  
Time Domain ◽  
Vibration Isolation ◽  
Wind Wave ◽  
Time History ◽  
Coupled System ◽  
Time Domain Analysis ◽  
Domain Analysis ◽  
Isolation Device ◽  
Nonlinear Time Domain

A mooring facility for a Floating Storage and Offloading (FSO) system, due to site conditions such as shallow water, often uses a fixed mooring tower for mooring of the FSO. When a fixed mooring tower in the form of a jacket structure is used, the turntable is mounted on the top of the jacket so that the FSO can weathervane due to actions of wind, wave and current forces. Product swivels are also located on this structure for uninterrupted flow of the product to the FSO when it rotates. The connection of the FSO to the turntable is through a rigid yoke. The yoke consists of two yoke arms meeting at a point hinged at the turntable, one large diameter cylinder for providing the stabilizing ballast load and two pendants supporting the ballast. The jacket has to be designed for the mooring loads in addition to the wind, wave and current loads on itself. The rigid yoke system is designed so that the varying draft conditions of the FSO as well as its motions can be suitably handled and absorbed. Complications may arise when the jacket is located in a seismically active site. When a site is prone to very strong ground motions, seismic response of the jacket in conjunction with the moored FSO has to be studied. The additional requirement is that any vibration of the jacket is suitably absorbed by the yoke system or a suitable isolation device is designed between the link or the yoke structure and the FSO. The weight of the suspended mass is a key design variable which affects this behavior. A structural dynamic model of the coupled jacket-yoke-frame-FSO system is analyzed using nonlinear time domain analysis technique. The calibrated El Centro ground accelerations are used for this analysis as a representative seismic excitation. A comparison of the results for jacket alone and the coupled system enables us to determine the effect of the yoke-frame-FSO on the dynamic response. The requirement, if any, of vibration isolation device for the nonlinear link (yoke) structure is decided from the dynamic analysis results. The dynamic analysis of the coupled system is complex. The complexities in the model arise due to: • The nonlinearity of the soil-pile system; • Nonlinearity of the yoke mechanism; • The fact that the FSO is a floating structure and it is free from the base excitation; • The FSO involves a large mass and is essentially free floating in water. The dynamic analyses are performed in several stages in view of the above complexities. Initially, the mode shapes and frequencies of the jacket alone are evaluated. Then the jacket is analyzed using the response spectrum approach with the design seismic spectrum. Subsequently time domain analysis of the jacket alone is performed using the calibrated El Centro seismic time history. Finally, the coupled system is analyzed for the time history of ground motion. Since the seismic event represents the design Strength Level Earthquake (SLE) condition, which is a rare event, only the FSO is coupled to the jacket, the offtake tanker is not assumed to be present during this extreme event. The nonlinear time domain analysis includes the nonlinear link (yoke) which is a mechanism by virtue of the hinges present. Therefore, the analysis requires geometric nonlinearity of the link to be considered to simulate the large displacements and the large rotations of the link, in addition to the nonlinearities of the pile-soil system. From the results of the analyses conclusions are drawn about effectiveness of vibration isolation by comparing the results of the jacket-yoke-FSO system to those of the jacket alone.

Nonlinear time‐domain analysis of electrostrictive materials by the finite element method

1997 ◽  
Vol 101 (5) ◽  
pp. 3165-3165
Author(s):  
Jocelyne F. Coutte‐Dubois ◽  
Jean‐Claude Debus ◽  
Bertrand Dubus ◽  
Regis Bossut
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Time Domain ◽  
Time Domain Analysis ◽  
Domain Analysis ◽  
The Finite Element Method ◽  
Element Method ◽  
Nonlinear Time Domain

Nonlinear time-domain analysis of coupled-cavity traveling-wave tubes

2002 ◽  
Vol 30 (3) ◽  
pp. 1024-1040 ◽  
Author(s):  
P. Freund ◽  
T.M. Antonsen ◽  
E.G. Zaidman ◽  
B. Levush ◽  
J. Legarra
Keyword(s):  
Time Domain ◽  
Traveling Wave ◽  
Time Domain Analysis ◽  
Domain Analysis ◽  
Traveling Wave Tubes ◽  
Coupled Cavity ◽  
Nonlinear Time Domain

Study on the Parametric Rolling of Medium-Sized Containership Based on Nonlinear Time Domain Analysis

2020 ◽  
Author(s):  
Seung Ho Yang
Keyword(s):  
Mathematical Model ◽  
Numerical Model ◽  
Wave Height ◽  
Time Domain ◽  
Time Domain Analysis ◽  
Domain Analysis ◽  
Wave Period ◽  
Irregular Waves ◽  
Parametric Rolling ◽  
Nonlinear Numerical Model

Abstract The numerical analysis of parametric rolling of medium-sized containership has been carried out. Target containership was modeled by using two different numerical models, which are nonlinear numerical model and simplified dynamic mathematical model respectively. The simulations were performed in full-loaded operating condition for regular and irregular waves. For regular waves, the analysis was conducted with a wide range of wave periods including the vicinity of the wave period expected to cause parametric rolling of the target containership. On the other hand, regarding irregular waves, the wave period range that is highly likely to occur according to significant wave height was selected and used as input values of wave spectrum for nonlinear time domain analysis. The analysis results are summarized as wave height versus wave period diagrams with the occurrences of parametric rolling motions for each speed. And also, time series based on time domain analysis are represented and compared between nonlinear numerical model and simplified dynamic mathematical model. In addition, the sensitivity of key parameters such as vessel speed, wave period, and roll damping to parametric rolling was investigated and estimated under operating condition. Finally, when the parametric rolling occurred, the characteristics of heave, pitch, and roll motions were analyzed. This study could be used as the basic data for determining the operational conditions for safe operation as well as initial design of the medium-sized containership.

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