A. Magnusson, K. Trulsen, O. Aarnes, E. Bitner-Gregersen, M. Malila
{"title":"“Three Sisters” Measured As a Triple Rogue Wave Group","authors":"A. Magnusson, K. Trulsen, O. Aarnes, E. Bitner-Gregersen, M. Malila","doi":"10.1115/omae2019-96837","DOIUrl":"https://doi.org/10.1115/omae2019-96837","url":null,"abstract":"\u0000 On November 30, 2018, our attention was caught when analyzing wave profile time series measured by a platform mounted wave sensor (a SAAB REX radar) at Ekofisk, central North Sea. The 20-minute time series had not only one, but three consecutive waves with individual heights that all were more than twice the significant wave height, the two last of them being almost equally high with a factor 2.35 to the significant wave height of 4m (from 4σ(η), over 20 minutes).\u0000 Counting three rogue waves in one sequence seems to be very rare. In this study we analyze how the shape is evolving in space and time using linear and non-linear propagation methods developed by Mark Donelan [1,2] and Karsten Trulsen [3,4]. Weather conditions and characteristics of the sea state with the ‘Three Sisters’ (named the “Justine Three Sisters”) are presented. It is found that the Three Sisters occurred in a crossing sea condition, with wind sea and swell coming from directions 60 degrees apart, with about same frequency, but very different energy.","PeriodicalId":314553,"journal":{"name":"Volume 3: Structures, Safety, and Reliability","volume":"54 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125432530","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
D. Abreu, C. Morais, J. Santos, Danilo Colombo, M. Martins
{"title":"Well Integrity: Preliminary Risk Analysis for Different Well Life Cycle Phases","authors":"D. Abreu, C. Morais, J. Santos, Danilo Colombo, M. Martins","doi":"10.1115/omae2019-96280","DOIUrl":"https://doi.org/10.1115/omae2019-96280","url":null,"abstract":"The life cycle of an oil well contains several phases, such as design, construction (drilling, completion and evaluation), production, intervention and abandonment. Moreover, each phase includes its particular operational modes (e.g., in the intervention phase there are wireline and coiled tubing operations). One of the main concerns during each phase refers to the risk of uncontrolled hydrocarbon flow to the environment, which is mitigated by measures that ensure well integrity through the use of well barriers. In this sense, the concept of two independent well barriers, reinforced by standards such as NORSOK D-010, leads the efforts in the industry, but does not clearly addresses the risks.\u0000 A failure in the well barrier elements leads to undesired events involving oil flow to the environment, damages to equipment and personnel loses. However a full comprehension of how these events contribute to the risk should take into account factors regarding the operational conditions. For instance, when the wellbore is exposed, an influx of hydrocarbons tends to release a biggest amount of oil to the environment than when the completion is installed. Additionally, older wells tend to sustain a smaller pressure when compared to other wells in the beginning of their life cycles — what also impacts on the consequences of undesired hydrocarbon flows. Nonetheless, these accidents should be pondered by their probability of occurrence for a full addressment of the risk.\u0000 In order to contribute to a risk-oriented view of issues related to well integrity, this work presents a customized Preliminary Risk Analysis framework. The simultaneous combination of well barrier elements failures constitutes the base of the analysis, which is complemented by control and monitoring measures. Hazards are also described according to their operational conditions, allowing treating this aspect separately.","PeriodicalId":314553,"journal":{"name":"Volume 3: Structures, Safety, and Reliability","volume":"38 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122350216","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"An Empirical Formula for Predicting Elastic Ultimate Buckling Strength of Flat-Bar Stiffened Panels With Initial Imperfections","authors":"H. Mei, De-yu Wang","doi":"10.1115/omae2019-95683","DOIUrl":"https://doi.org/10.1115/omae2019-95683","url":null,"abstract":"\u0000 Elastic ultimate buckling strength is an important strength design criteria to estimate the safety margin of stiffened panels subjected to axial compressive load. Based on a series of Nonlinear finite elements analysis, an empirical formula is proposed to elastic ultimate buckling strength of stiffened panels with flat-bar stiffener in this study. The elastic ultimate buckling strength is defined as that in the loading process, a certain average compressive stress of stiffened panels when the Vonmises stress of structures firstly reach the yield stress. The range of geometrical sizes for numerical samples is discussed in order to ensure the applicability of presented empirical formula. The extent of models and initial imperfection, namely initial geometrical deformation are also taken into account. Ultimately, it is shown that there are a good agreement between the results of Non-linear finite element method and the proposed empirical formula.","PeriodicalId":314553,"journal":{"name":"Volume 3: Structures, Safety, and Reliability","volume":"59 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114341285","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Estimation and Comparison of Accuracy in Various Data Resolutions on Optimal Ship Routing Across the North Pacific Ocean","authors":"K. Sasa, Takuya Fujimatsu, Chen Chen, R. Shoji","doi":"10.1115/omae2019-95173","DOIUrl":"https://doi.org/10.1115/omae2019-95173","url":null,"abstract":"\u0000 The amount of maritime cargo has been increasing for several decades. However, most seafarers have been shifting from lifetime employment to temporary employment. This may result in the ships lacking the adept techniques of seafarers, which significantly increases the reliance and importance of operational support systems. There are many studies on optimal ship routing, but its accuracy has not been discussed sufficiently. Especially, the grid point value on the weather database is the most important factor to discuss regarding its accuracy. In the field of meteorology, these databases have been improved to include global data in recent decades. In this study, the simulation results are compared to know the influence to the accuracy if the spatial and time resolutions vary in each condition. Optimal ship routing is computed using the isochrone method, which is one of the major methods of route analysis. Numerical simulations are conducted for a container ship between Tokyo and Los Angeles, with the weather databases of National Centers for Environmental Prediction (NCEP) and National Oceanic and Atmospheric Administration (NOAA). It is known that there are no significant differences between each resolution setting. However, the optimal voyage routes are different if the ship avoids high waves or strong winds in any direction. The accuracy is more influenced by the maneuverability in rough seas than the spatial and time resolutions of the weather databases. Accordingly, optimal ship routing must consider the actual maneuvering and speed loss theories, besides the development of a meteorological database.","PeriodicalId":314553,"journal":{"name":"Volume 3: Structures, Safety, and Reliability","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130521124","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Validation of External Moment Determination for the Shaft-Line of the S.A. Agulhas II","authors":"B. M. Nickerson, A. Bekker","doi":"10.1115/omae2019-96746","DOIUrl":"https://doi.org/10.1115/omae2019-96746","url":null,"abstract":"\u0000 Full-scale measurements of shaft torque have been performed on several voyages of a polar supply and research vessel, the SA Agulhas II. Previous work has looked at the determination of the externally induced ice moments on the propeller to shed light on the expected loading conditions in the harsh Antarctic environments. This has been done by making use of a lumped mass model, measurements taken on the shaft-line and an inverse prediction algorithm. Thus the externally applied loads are determined through the internal measurements on the shaft-line. The work presented here is in an effort to assess the validity of the lumped mass model parameters used in the external moment determination process. Two methods of validation have been performed. The first is through the comparison of the lumped mass model to operational modal analysis data of the shaft-line, obtained during dry-dock operations in 2017. The second validation method that is considered relies on data recorded on board the SA Agulhas II during its 2018–19 Annual Relief Voyage to Antarctica. The shaft-line measurement system has been expanded to include the measurement of torque at a second location, further down the shaft. These two measurement locations are each used to determine the external loads and their results are compared. It was found that the results of the validation show correlation, albeit with some error, and that the developed method is valid for use in determining externally induced ice moments. However, there is room for improvement of the current external moment determination method.","PeriodicalId":314553,"journal":{"name":"Volume 3: Structures, Safety, and Reliability","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132422969","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Analysis of Fatigue Life of Ship Structure Under the Non-Linear Slamming Load","authors":"H. Ren, Hezhong Ma","doi":"10.1115/omae2019-95781","DOIUrl":"https://doi.org/10.1115/omae2019-95781","url":null,"abstract":"\u0000 As one of the hot topics in ship structures, hull structural fatigue has been widely studied by overseas and domestic scholars in recent years. And fatigue assessment methods can be divided into simplified calculation method and direct calculation method. However most of the calculation methods are based on liner wave load. Some high-speed ships, large external floats and larger ships may have frequent outflows and inflows during the voyage. These ships can be influenced by more serious wave attack. In this situation, the influence of nonlinear slamming load on ship structures cannot be ignored. In this paper, the author selected the deck longitudinal and the bottom longitudinal of the example ship midship section, then calculated the fatigue damage under the action of liner load and total fatigue damage under non-linear slamming load respectively.\u0000 And the effect of non-linear slamming load on the fatigue life of hull structure can be obtained: it is 49% larger than that without attack fatigue damage in the deck longitudinal, and 35% larger in the bottom longitudinal. Based on the results, the author got the influence coefficient of non-linear slamming load on the fatigue life of the ship. Finally, a nonlinear correction method of fatigue damage is proposed.","PeriodicalId":314553,"journal":{"name":"Volume 3: Structures, Safety, and Reliability","volume":"68 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128765063","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
V. Laface, E. Bitner-Gregersen, F. Arena, A. Romolo
{"title":"A Parameterization of DNV GL Storm Profile for Long-Term Analysis of Ocean Storms: Trapezoidal Storm Model","authors":"V. Laface, E. Bitner-Gregersen, F. Arena, A. Romolo","doi":"10.1115/omae2019-95880","DOIUrl":"https://doi.org/10.1115/omae2019-95880","url":null,"abstract":"\u0000 The paper introduces a parameterization of the DNV GL storm profile for developing an analytical model for calculations of the return period of a storm whose peak exceeds a given threshold. The DNV GL storm evolution is represented via an isosceles trapezoidal shape in which the minor base represents the storm peak duration, the major base the total storm duration and the height is half of the highest significant wave height in the actual storm. In this representation, the storm duration is not related to the storm intensity and it is fixed constant and equal to 42 hours, while the peak duration is assumed to be 6 hours. The parameterization proposed in the paper consists in expressing the peak duration as a fraction of the total storm duration allowing to investigate the effects of storm peak duration on long term estimates. The analytical solution for the return period is derived by following the classical approach of Equivalent Storm Models that is referring to the equivalent storm sequence, with the only difference that all the Trapezoidal Storm durations are identical whatever the storm intensity is. This assumption leads to significant simplification on the model development and potential employment as well. Further, a closed form solution is achieved for the return period which is also a generalization of the triangular shape. Finally, data analysis with NDBC buoys data is carried out for validating the model and elucidating analogies and differences with respect to classical Equivalent Storm approach. Results have shown that the Trapezoidal Model can be thought as a triangular one with a prudential factor on the storm peak duration which results in a reasonable overestimation of maximum expected wave height and return values.","PeriodicalId":314553,"journal":{"name":"Volume 3: Structures, Safety, and Reliability","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126886049","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
S. Rajaratnam, T. Sriskandarajah, D. Clayton, G. Roberts, Vincent Loentgen, Carlos Charnaux
{"title":"Analytical Methods for Preliminary Design of Anchor Flanges for Subsea Structures","authors":"S. Rajaratnam, T. Sriskandarajah, D. Clayton, G. Roberts, Vincent Loentgen, Carlos Charnaux","doi":"10.1115/omae2019-95051","DOIUrl":"https://doi.org/10.1115/omae2019-95051","url":null,"abstract":"\u0000 Anchor flanges are interface items which are used to connect pipelines to subsea in-line and end termination structures. They are forged and tend to be long-lead items; therefore, the design of an anchor flange should be completed at a very early project stage, possibly even during the tender phase. An optimised, analytical method for preliminary design would result in reduced design time overall and have beneficial cost implications.\u0000 The analytical notch methods (i.e. Neuber’s and Glinka’s) that are presented utilise linear-elastic stress concentration factors to make realistic predictions of the ultimate load carrying capacity of an anchor flange in the non-linear regime.\u0000 The linear-elastic stress concentration factor values are calculated with simple analytical formulae and graphs. The analytical notch methods are deployed to predict the anchor flange limit load and peak plastic strain and thereby ensure that the plastic strain remains within the allowable limits of design codes.\u0000 The cost and time saving associated with the analytical notch methods, and the accuracy that is maintained, are assessed by comparison with the predictions results obtained from detailed finite element analyses.","PeriodicalId":314553,"journal":{"name":"Volume 3: Structures, Safety, and Reliability","volume":"106 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116546332","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Numerical Simulation and Analysis of Phase Focused Breaking and Non-Breaking Wave Impact on Fixed Offshore Platform Deck","authors":"Rameeza Moideen, M. Behera, A. Kamath, H. Bihs","doi":"10.1115/omae2019-95193","DOIUrl":"https://doi.org/10.1115/omae2019-95193","url":null,"abstract":"\u0000 Extreme wave impact due to tsunamis and storm surge create large wave heights causing destruction to coastal and offshore structures. These extreme waves are represented by focused waves in the present study and the impact on offshore deck is studied. Numerical wave tank used is modelled using open-source software REE3D, where the level set method is used to capture the air-water interface. Vertical impact force on offshore deck is computed and compared with the experimental results to validate the numerical model. Focused wave is generated by phase focusing a group of waves at a particular position and time. The nonlinearity of focused wave and its effect on the vertical impact force is quantified for different airgap and increasing wave heights. The steepness of this focused wave is increased to initiate phase focused breaking in the numerical wave tank, which is validated with experimental results of Ghadirian et al., 2016. The main purpose of this paper is to examine breaking focused wave group loads on the offshore deck and to study the impact on deck at different breaking locations. The positioning of the deck with respect to breaker location have shown that the maximum horizontal impact force due to breaking wave occurs when the plunging crest hits the deck side.","PeriodicalId":314553,"journal":{"name":"Volume 3: Structures, Safety, and Reliability","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114469897","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"An Ontology-Based Approach for Developing Offshore and Onshore Process Equipment Inspection Knowledge Base","authors":"Andika Rachman, R. Ratnayake","doi":"10.1115/omae2019-95478","DOIUrl":"https://doi.org/10.1115/omae2019-95478","url":null,"abstract":"\u0000 A collection of inspection results is an essential input in assessing and managing the technical integrity of offshore and onshore process equipment. The inspection results enable the current condition of the equipment, the type of damage mechanism, and the severity and location of the degradation to be investigated. Typically, the inspection results are documented in a text-format report and stored in a conventional data repository. Conventional inspection data storage has drawbacks in terms of the sharing, exchange, and retrieval of information within an inspection knowledge domain, due to the lack of knowledge representation. This study proposes an ontology-based approach for developing an inspection knowledge base, in order to improve the degree of retrieval, distribution, and administration of inspection results. Ontology provides a semantic structure and relations for concepts in the inspection knowledge domain, which facilitate semantic search capability and enable increased utilization, enhanced communication and improved exchange of inspection information. A case study of a static equipment inspection is shown, to demonstrate the application of an ontology-based approach in facilitating data and information retrieval from an inspection knowledge base.","PeriodicalId":314553,"journal":{"name":"Volume 3: Structures, Safety, and Reliability","volume":"95 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116530033","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}