Study on the IMO Second Generation Intact Stability Criteria of Surf-riding/Broaching Failure Mode

2015 ◽  
Author(s):  
Peiyuan Feng ◽  
Xingrong Shen ◽  
Sheming Fan
Keyword(s):  
Failure Mode ◽  
Model Experiment ◽  
Ship Design ◽  
Sensitivity Analyses ◽  
Numerical Code ◽  
Stability Criteria ◽  
Intact Stability ◽  
Free Running ◽  
Surf Riding ◽  
Potential Impact

A series of investigations on the vulnerability criteria for the surf-riding/broaching stability failure mode is conducted. First and foremost, free running model experiment of a purse seiner in severe following waves is performed to demonstrate the fatalness of surf-riding/broaching. The latest IMO proposal to assess broaching stability failure mode is then studied in detail. A numerical code with user interface is developed to facilitate sensitivity analyses and sample ship calculations. The appropriateness of the proposal is analyzed and its potential impact on ship design is discussed.

Application of the Second Generation Intact Stability Criteria in Initial Ship Design

2014 ◽  
Author(s):  
M. Tompuri ◽  
P. Ruponen ◽  
M. Forss ◽  
D. Lindroth
Keyword(s):  
Second Generation ◽  
Failure Modes ◽  
Ship Design ◽  
Stability Criteria ◽  
Parametric Roll ◽  
Safety Measures ◽  
Main Emphasis ◽  
Intact Stability ◽  
Surf Riding ◽  
Additional Safety

The International Maritime Organization (IMO) is revising the Intact Stability Code. The so-called second generation intact stability criteria will provide additional safety measures against stability failures in waves. The draft regulations for three failure modes, parametric roll, pure loss of stability and surf-riding/broaching are reviewed and sample calculations for a fast RoPax ship are presented. The main emphasis is on the sensitivity of the results to the applied input data, which is not very accurate in the initial design phase. The implementation and effects of the new calculations to the ship design are discussed.

scholarly journals IMO Second Generation Intact Stability Criteria: General Overview and Focus on Operational Measures

2020 ◽  
Vol 8 (7) ◽  
pp. 494
Author(s):  
Nicola Petacco ◽  
Paola Gualeni
Keyword(s):  
Second Generation ◽  
Methodological Approach ◽  
Ship Design ◽  
Stability Assessment ◽  
Stability Criteria ◽  
Comprehensive Overview ◽  
Complementary Action ◽  
Intact Stability ◽  
Insight Into ◽  
Operational Aspects

At the beginning of 2020, after a long and demanding process, the Second Generation Intact Stability criteria (SGISc) have been finalized at the 7th session of the International Maritime Organization (IMO) sub-committee on Ship Design and Construction (SDC). At present, SGISc are not mandatory, nevertheless IMO endorses their application in order to assess their consistency and validity. It is envisaged that SGISc can support the design of safer ships, nevertheless such a rules framework might have an impact also on the ship operational aspects in a seaway. In fact, within the SGISc framework, Operational Measures have also been implemented providing guidance and limitations during navigation. After a comprehensive overview about SGISc vulnerability levels and direct stability assessment, this paper provides a specific insight into the methodological approach for the Operational Measures extensively addressed as a complementary action to ship design.

Second Generation Intact Stability Criteria Fallout on Naval Ships Limiting KG Curves

2020 ◽  
Author(s):  
Gennaro Rosano ◽  
Ermina Begović ◽  
Guido Boccadamo ◽  
Barbara Rinauro
Keyword(s):  
Dynamic Stability ◽  
Second Generation ◽  
Loss Of Stability ◽  
Stability Criteria ◽  
Parametric Roll ◽  
Intact Stability ◽  
Surf Riding ◽  
Hull Forms ◽  
Onr Tumblehome ◽  
Dead Ship Condition

The International Maritime Organization (IMO) finalized the Second Generation Intact Stability Criteria (SGISC), in February 2020. They are intended to be included in Part A of the 2008 International Code on Intact Stability in the following years. The SGISC consider five modes of dynamic stability failure in waves: parametric roll, pure loss of stability, surf-riding/broaching to, dead ship condition and excessive acceleration. In this paper, two semi-displacement, round bilge and transom stern hull forms, the parent hull of the Systematic Series D and the ONR Tumblehome, i.e. typical naval hull forms, are examined. Although naval ships are not directly impacted by SGISC, they are sensitive to dynamic stability failure phenomena due to their geometry and range of service speeds. The procedures to assess the ship vulnerability to the dead ship condition and excessive acceleration criteria, referring to the latest drafts of the criteria (SDC 7/5, 2019), were implemented in Matlab®,. The limiting KG curves associated with this set of criteria were obtained for each vessel. The minimum allowable KG curve associated with the excessive acceleration criterion was compared with the maximum allowable KG curve associated with dead ship condition, to investigate the existence of a safe operational area.

Evaluation of the Dynamic-Response-Based Intact Stability Criterion for Floating Wind Turbines

2015 ◽  
Author(s):  
Marco Masciola ◽  
Xiaohong Chen ◽  
Qing Yu
Keyword(s):  
Wind Speed ◽  
Dynamic Response ◽  
Wind Turbines ◽  
Stability Criterion ◽  
Area Ratio ◽  
Operating Conditions ◽  
Dynamic Responses ◽  
Stability Criteria ◽  
Intact Stability ◽  
Overturning Moment

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.

Experimental Research on the Surf-Riding Region for High Speed Vessels

2015 ◽  
Author(s):  
Atsuo Maki ◽  
Yoshiki Miyauchi
Keyword(s):  
Experimental Research ◽  
High Speed ◽  
Safety Assessment ◽  
Estimation Methods ◽  
Model Experiments ◽  
Size Limitation ◽  
Analytical Estimation ◽  
Free Running ◽  
Surface Combatant ◽  
Surf Riding

It is well known that surf-riding phenomenon is the prerequisite of the broaching-to in following and quartering conditions. For the safety assessment of the fast vessel such as surface combatant sand patrol crafts, the estimation of the surf-riding condition is important. Therefore, so far several experimental efforts have been made. However, in these previous researches, the free running model experiments in high speed region, i.e.up to Froude number of 0.6 or 0.7, have not been conducted because of tank size limitation. As shown in this paper, there are occurrence and disappearance boundaries of surf-riding in lower and faster region, respectively. In our study, free running model experiments are carried out in high speed region, and then both boundaries are experimentally obtained. By using obtained results, the analytical estimation methods proposed by the authors can be well validated. Furthermore, the free running model experiments in irregular seas are also conducted. Then, surf-riding phenomenon in irregular seas is also discussed.

Hydrodynamic Aspects on Vulnerability Criteria for Surf-Riding of Ships

2014 ◽  
Vol 66 (2) ◽  
Author(s):  
Yuto Ito ◽  
Naoya Umeda ◽  
Hisako Kubo
Keyword(s):  
Empirical Formula ◽  
Global Bifurcation ◽  
Quantitative Agreement ◽  
Hydrodynamic Theory ◽  
Safety Level ◽  
Slender Body Theory ◽  
Model Experiments ◽  
Intact Stability ◽  
Surf Riding ◽  
Wave Induced

For developing the International Maritime Organization (IMO) second-generation intact stability criteria regarding broaching, draft vulnerability criteria for surf-riding were agreed at the IMO in 2012. This paper describes their hydrodynamic backgrounds with captive model experiments for seven ships, a hydrodynamic theory and a random process theory. In the first level vulnerability criteria, a ship is required to reduce her Froude number of less than 0.3 in case of severe following waves. For predicting the surf-riding threshold in a global bifurcation theory, it is necessary to precisely estimate wave-induced surge force. Thus, the authors execute captive model experiments for three ships in model basins. As a result, we confirmed that the Froude-Krylov calculation overestimates the amplitude of wave-induced surge force so that an empirical formula for regulatory application is presented. For investigating the reason of this discrepancy, a slender body theory assuming low encounter frequency is applied to the situation where a ship runs with a wave. This theory suggests that change of wave-making resistance due to incident wave could reduce the amplitude of the wave-induced surge force and quantitative agreement with model experiment requires the use of CFD or an empirical formula. Thus, the authors can recommend the use of experimental correction formula for the vulnerability criteria. Based on sample calculation results of surf-riding probability of six ships in the North Atlantic, the safety level to be required in the criteria is proposed.

Modeling Studies on Microbial Effects on Groundwater Chemistry

2006 ◽  
Vol 985 ◽  
Author(s):  
Yoshikatsu Tochigi ◽  
Hideki Yoshikawa ◽  
Mikazu Yui
Keyword(s):  
Redox Potential ◽  
Microbial Activity ◽  
Specific Activity ◽  
Measurement Techniques ◽  
Groundwater Chemistry ◽  
Sensitivity Analyses ◽  
Numerical Code ◽  
Sulfate Reducing ◽  
Geochemical Parameters ◽  
Microbial Effects

AbstractThe overall goal of this project is to develop a model to predict microbial effects on the performance of a high-level radioactive waste (HLW) repository. As a first step, the effects of microbes on groundwater chemistry have been evaluated with the numerical code 'MINT', using data collected from the borehole HDB-6 in the Horonobe underground research laboratory (URL) in Japan. The MINT code models biochemistry and geochemical equilibrium, with consideration of transport of solute and microbial activity. The MINT code simulates the activities of 6 major groups of microbes, classified by their metabolism as 'aerobic', 'denitrifying', 'manganese reducing', 'iron reducing', 'sulfate reducing' and 'methanogenic'. The specific activity of each of these groups will depend on the redox potential (Eh) of the groundwater.Sensitivity analyses were performed to investigate the consequences of changes in groundwater composition on the effects of microbial activity. This indicates that the activities of Sulfate Reducing Bacteria (SRB) and methanogens are relatively high. The concentration of dissolved methane produced by such microbial activity is seen to be influenced by sulfate concentration. Based on the observed data from Horonobe URL, the concentration in oxygen is relatively high and the activity of denitrifying bacteria is the highest of the major 6 groups of microbes. This can, however, be attributable to chemical / microbial contamination of the groundwater during sampling. The modeling results indicate that the concentration of dissolved oxygen and nitrate ion should be quickly reduced by microbial metabolism, reducing the redox potential to a level low enough for active methanogenesis to commence. Such assessment can be important to evaluate the reliability of sampling and measurement techniques for sensitive geochemical parameters in general - and microbiology in particular.

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