scholarly journals A proposed new generation of intact stability criteria for assessment of ship stability in longitudinal waves

Author(s):  
C Andrei
Teknik ◽  
2021 ◽  
Vol 42 (1) ◽  
pp. 52-62
Author(s):  
Alamsyah Alamsyah ◽  
Zen Zulkarnaen ◽  
Suardi Suardi

Ship stability that is not according to the IMO standard will make the ship capsize when operating. The purpose of this research is to determine the cause of the overturn in terms of the stability criteria of the ship. The method used is software  of simulation. Stability analysis is carried out with the load case that occurs in the field when an accident occurs and the ideal loadcase according to PM 104 2017 standards about’s the transportation of operation. The results showed is cargo of goods placed on the roof top (loadcase 1) based on the criteria of Intact Stability; area of the stability arm curve at heeling 0° ~ 30° = 0.9417 m.deg, area 0° ~ 40° = 1,0200 m.deg, 30° ~ 40° = 0.0783 m.deg, GZ value at heeling 30° = 0.029 m, angle of occurrence of maximum GZ = 21.8°, and the initial GMt value = 0.135 m, the results stated that all did not meet the Intact Stability code A.749 criteria, while in it was obtained cargo of goods placed in the hull (loadcase 2) based on Intact Stability; area of the stability arm curve at heeling 0° ~ 30° = 4.5338 m.deg, area 0° ~ 40° = 7.1643 m.deg, area 30° ~ 40° = 2.6305 m.deg, GZ value at heeling 30° = 0.265 m, angle of occurrence of maximum GZ = 34.5°, and the initial GMt value = 0.621 m, the results stated that all met the Intact Stability code A.749 criteria


2020 ◽  
pp. 1-14
Author(s):  
Nicola Petacco ◽  
Giuliano Vernengo ◽  
Diego Villa ◽  
Antonio Coppedé ◽  
Paola Gualeni

The sensitivity of ship stability performance in waves to geometric variation has been investigated by means of a simulation-based design framework. The study was devoted to assess the influence of hull geometry variations on some stability failure modes, namely, parametric roll (PR) and pure loss of stability (PLS). The application has been developed by using a representative model of a postpanamax container vessel. PR and PLS phenomena have been investigated by the application of second-generation intact stability criteria (SGISc). The initial multidimensional design space has been filled by 500 design configurations identified by means of a design of experiments approach. A method developed in-house, combining the subdivision surface and free-form deformation approaches, has been used to create the whole set of design alternatives. The generated design configurations have been assessed analyzing the results derived from application of the first- and the second-level SGIS vulnerability criteria for both the selected stability failure modes. To strengthen the correlation behaviors, the design space has then been further explored by using 10k design configurations exploiting the capabilities of a surrogate model-based approximation, relying on a Gaussian process formulation. The study has been focused on the correlations among the variables and the response functions, i.e., the outcomes of the SGIS vulnerability criteria. The significance, in terms of effects, of each geometry shape variable has been investigated. Results have been discussed in the light of the SGISc structure, to provide further insight into this innovative safety framework for a modern approach to intact stability. 1. Introduction In the last 10 years, the development of the so-called second-generation intact stability criteria (SGISc) has been one of the most engaging topics addressed by the Sub-Committee on Safety Design and Construction (SDC) of the International Maritime Organization (IMO).


2019 ◽  
Vol 161 (A3) ◽  

The International Maritime Organization is currently establishing second generation intact stability criteria, the dead ship stability is considered one important criterion, so the development of its direct stability assessment regulation has become a topic undergoing close review. In this paper a peak-over-threshold (POT) method is proposed to evaluate the dead ship stability, which focuses on the statistical extrapolation that exceed the threshold, also the traditional Monte Carlo simulation is carried out to approve the method. On the basis of verification calculation of the sample ship CEHIPAR2792, the capsizing probability of a certain warship is also conducted. Moreover, the influence of initial stability height GM and effective wave slope coefficient on the capsizing probability is analysed. The results and the possible reason for the difference are examined. This study is expected to provide technical support for the second-generation stability criteria and establish the capsizing probability of damaged dead ship stability.


2019 ◽  
Vol 161 (A3) ◽  
Author(s):  
LF Hu ◽  
QZ Zhang ◽  
WY Zhang ◽  
HB Qi

The International Maritime Organization is currently establishing second generation intact stability criteria, the dead ship stability is considered one important criterion, so the development of its direct stability assessment regulation has become a topic undergoing close review. In this paper a peak-over-threshold (POT) method is proposed to evaluate the dead ship stability, which focuses on the statistical extrapolation that exceed the threshold, also the traditional Monte Carlo simulation is carried out to approve the method. On the basis of verification calculation of the sample ship CEHIPAR2792, the capsizing probability of a certain warship is also conducted. Moreover, the influence of initial stability height GM and effective wave slope coefficient on the capsizing probability is analysed. The results and the possible reason for the difference are examined. This study is expected to provide technical support for the second-generation stability criteria and establish the capsizing probability of damaged dead ship stability.


Author(s):  
L F Hu ◽  
Q Z Zhang ◽  
W Y Zhang ◽  
H B Qi

The International Maritime Organization is currently establishing second generation intact stability criteria, the dead ship stability is considered one important criterion, so the development of its direct stability assessment regulation has become a topic undergoing close review. In this paper a peak-over-threshold (POT) method is proposed to evaluate the dead ship stability, which focuses on the statistical extrapolation that exceed the threshold, also the traditional Monte Carlo simulation is carried out to approve the method. On the basis of verification calculation of the sample ship CEHIPAR2792, the capsizing probability of a certain warship is also conducted. Moreover, the influence of initial stability height GM and effective wave slope coefficient Y on the capsizing probability is analysed. The results and the possible reason for the difference are examined. This study is expected to provide technical support for the second-generation stability criteria and establish the capsizing probability of damaged dead ship stability.


Author(s):  
Р.В. Борисов ◽  
М.А. Кутейников ◽  
А.А. Лузянин ◽  
В.Р. Самойлов

При создании норм для морских судов, попадающих в разнооб­разные гидрометеорологические условия, достоверный расчет кренящих моментов затруднителен, и задача определения мини­мально допустимых характеристик остойчи­вости (критериев) решалась путем анализа статистических данных об остойчивости судов, успешно эксплуатировавшихся или потерпевших аварию вследствие недоста­точной остойчивости. Применительно к тре­бованиям ИМО в качестве нормируемых характеристик остойчивости были приняты характеристики начальной остойчивости и диаграммы статической остойчивости. В настоящее время в ИМО ведется активная работа по созданию критериев остойчивости нового поколения, учитывающих более широкий круг явлений, опасных с точки зрения остойчивости судна, Действующие нормы Кодекса ИМО по остойчивости 2008 года их не учитывают. С учетом близости отечественных и международных методик оценки кратковременных и долговременных показателей мореходности анализируются результаты этой работы и оценивается возможность использования предлагаемых в ИМО подходов в отечественной практике нормирования море­ходности. For sea going ships operated in different hydro meteorological conditions reliable determination of heeling moments is difficult and the task of obtaining minimum allowable stability characteristics (criteria) was done by statistical stability analysis of ships successfully operated or capsized due to lack of stability. At IMO requirements intact stability was regulated by meta centric height ana stability diagram requirements. Currently, IMO is actively working on creating new generation stability criteria, which take into account a wider range of phenomena hazardous in terms of ship stability. The current standards of the IMO Stability Code 2008 do not take them into account. Considering the proximity of domestic and international methods for assessing short-term and long-term seaworthiness indices, the results of this work are analyzed and the possibility of using the approaches proposed by IMO in the domestic practice of seaworthiness rationing is evaluated.


Author(s):  
Marco Masciola ◽  
Xiaohong Chen ◽  
Qing Yu

As an alternative to the conventional intact stability criterion for floating offshore structures, known as the area-ratio-based criterion, the dynamic-response-based intact stability criteria was initially developed in the 1980s for column-stabilized drilling units and later extended to the design of floating production installations (FPIs). Both the area-ratio-based and dynamic-response-based intact stability criteria have recently been adopted for floating offshore wind turbines (FOWTs). In the traditional area-ratio-based criterion, the stability calculation is quasi-static in nature, with the contribution from external forces other than steady wind loads and FOWT dynamic responses captured through a safety factor. Furthermore, the peak wind overturning moment of FOWTs may not coincide with the extreme storm wind speed normally prescribed in the area-ratio-based criterion, but rather at the much smaller rated wind speed in the power production mode. With these two factors considered, the dynamic-response-based intact stability criterion is desirable for FOWTs to account for their unique dynamic responses and the impact of various operating conditions. This paper demonstrates the implementation of a FOWT intact stability assessment using the dynamic-response-based criterion. Performance-based criteria require observed behavior or quantifiable metrics as input for the method to be applied. This is demonstrated by defining the governing load cases for two conceptual FOWT semisubmersible designs at two sites. This work introduces benchmarks comparing the area-ratio-based and dynamic-response-based criteria, gaps with current methodologies, and frontier areas related to the wind overturning moment definition.


1999 ◽  
Vol 36 (03) ◽  
pp. 171-174
Author(s):  
Hüseyin Yilmaz ◽  
Abdi Kükner

It is well known that stability is the most important safety requirement for ships. One should have some information on ship stability at the preliminary design stage in order to reduce risk. Initial stability of ships is an important criterion and can be closely evaluated in terms of form parameters and vertical center of gravity. In this study, using some sample ship data, approximate formulations are derived by means of regression analysis for the calculations expressed in terms of ship preliminary design parameters that can easily provide approximate GM calculations. Thus designers can be provided with ship stability at the preliminary design stage, and also a set of appropriate design parameters for improving vessel stability can easily be determined.


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