Volume 3: Structures, Safety, and Reliability最新文献

{"title":"Finite Element Analysis of the Effect of Twist on Chain Fatigue Performance","authors":"Justin M. Jones","doi":"10.1115/omae2019-95276","DOIUrl":"https://doi.org/10.1115/omae2019-95276","url":null,"abstract":"\u0000 Mooring chains may be installed with twist or become twisted during service. This paper describes an investigation of the effect of a range of twist angles on the fatigue life of studless chain through the use of detailed finite element analysis.\u0000 The analysis includes the local contact patch deformation and residual stress state that results from plasticity during the proof testing of the chain. The effect of high in-service tension resulting from storms that produces additional plasticity when the chain is loaded in the twisted state is also included. The change in fatigue life at the crown, inner bend and around the contact patch are assessed. Local to the contact patch the fatigue life calculation includes an assessment of the multiaxial stress state.\u0000 For small angles of twist the calculated fatigue life at the crown and around the contact increases and that at the inner bend sees a marginal reduction. At twist angles above 12 to 14 degrees per link the calculated inner bend and contact patch fatigue lives reduce markedly with increasing twist, but the crown fatigue life continues to increase.","PeriodicalId":314553,"journal":{"name":"Volume 3: Structures, Safety, and Reliability","volume":"27 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":"116147331","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":"Extending Integrability of Nonlinear Water Wave Equations: Nonlinear Fourier Analysis of Breather Packets and Rogue Waves at Higher Order","authors":"A. Osborne","doi":"10.1115/omae2019-95543","DOIUrl":"https://doi.org/10.1115/omae2019-95543","url":null,"abstract":"\u0000 I suggest a formulation to give approximate spectral solutions of nonintegrable, nonlinear wave equations in 2+1 dimensions. Nonintegrable systems such as the 2+1 NLS, Dysthe and extended Dysthe equations can be approximately integrated by selecting a nearby theta function formulation. I study the subclass of wave equations that are in the form of nonlinear envelope equations for which all members can be reduced to a particular Hirota bilinear form. To find the approximately integrable formulation associated with a nonintegrable equation, I first study the one and two soliton solutions and subsequently extend these to larger numbers of solitons to obtain the Hirota N-soliton solution (for infinite-plane boundary conditions). Subsequently, I address the one and two periodic solutions from the bilinear form, so that I can develop the associated Riemann theta function solution to a nearby integrable case. I discuss how to obtain the higher order breather packets from the point of view of the theta functions. This work is being developed for real time analysis of shipboard radar analysis of ocean waves. Further applications include real time analysis of lidar and synthetic aperture radar (SAR) data taken by airplanes flying over high sea states.","PeriodicalId":314553,"journal":{"name":"Volume 3: Structures, Safety, and Reliability","volume":"33 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":"124447502","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":"Wave Load and Response Predictions Combining HOSM, CFD and Machine Learning","authors":"J. Oberhagemann, J. Kaufmann, A. K. Ervik, O. Gramstad, J. B. Helmers, F. Sireta","doi":"10.1115/omae2019-95352","DOIUrl":"https://doi.org/10.1115/omae2019-95352","url":null,"abstract":"\u0000 We present efforts to progress on numerical predictions of extreme wave loads of ships by combining a variety of state-of-the-art numerical tools. Aims are the generation of wave scenarios to represent the wave excitation and corresponding structural response associated with a pre-defined probability of, e.g., one expected exceedance per life cycle, as well as the further development of numerical methods to predict the ship response to the selected wave events.","PeriodicalId":314553,"journal":{"name":"Volume 3: Structures, Safety, and Reliability","volume":"19 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":"116661537","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":"Predictions of Tensile Strain Capacity for Strain-Based Pipelines With a Circumferential and Internal Surface Flaw","authors":"Y. Jang, Ju Kang, N. Huh, Ik-joong Kim, Cheol-man Kim, Young-pyo Kim","doi":"10.1115/omae2019-96480","DOIUrl":"https://doi.org/10.1115/omae2019-96480","url":null,"abstract":"\u0000 Strain-based design assessment (SBDA) has been known for suitable assessment concept for pipelines subjected to displacement-controlled load and high plastic deformation rather than conventional stress-based design assessment. Tensile strain capacity (TSC) has been used for one of important factors to indicate limit state in strain-based design, so that it is main concern to predict accurate TSC to ensure the structural safety and integrity of pipelines. For the pipeline containing a flaw, especially a girth weld flaw, TSC based on fracture mechanics can be determined. Crack-tip opening displacement (CTOD) has been widely used for typical elastic-plastic fracture parameter, representing crack-driving force and crack-resistance curve, which are required to assess unstable crack propagation. The one of the main principles of crack assessment is that the definitions of crack-driving force and crack resistance curve should be coincident. However, there exist two kinds of the definitions of CTOD, which are based on 90° and original crack-tip concept, and these have been not unified in practical regions until now. Moreover, it is reported that the deviations of crack-resistance curve can occur in the same specimen and experiment, caused by the different definitions of CTOD. Therefore, CTOD solutions based on each of different definitions of CTOD should be highly required since inaccurate TSC would be assessed when using not the identical definition of that.\u0000 In the present study, CTOD solutions of pipelines with a circumferential and internal surface flaw are suggested by using two kinds of definitions of CTOD based on 90° and original crack-tip concept. For this purpose, FE analyses were systematically carried out considering various pipe geometries and material properties. And single-edge notched tension (SENT) specimen was used for representing resistance curve of API X70/X65 material. Moreover, the effect of the choice of each CTOD definitions on TSC was investigated through crack-driving force diagram (CDFD) assessment.","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":"125650057","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":"Comparative Study on Fatigue Damage Assessment of a Structure Member in a Bulk Carrier Using Various Environmental Conditions","authors":"F. A. Prasetyo, N. Osawa, M. A. Kurniawan, S. Komariyah","doi":"10.1115/omae2019-96760","DOIUrl":"https://doi.org/10.1115/omae2019-96760","url":null,"abstract":"\u0000 Specific design life could be identified by using fatigue damage assessment in the structure engineering field as well as in the maritime sector. Fatigue assessment is one of the assessments to be conducted during review of ship structure design. Fatigue assessment of ship structural member is mainly conducted based on specific environmental condition. In general, specific environmental condition, which is provided by Classification Society rules, is a long term sea-state data of North Atlantic Ocean. The wave scatter diagram presents the tabulation of a long term data of sea state history in the specific ocean. Therefore, a realistic encounter of wave scatter diagram is essential to simulate the variation of wave loadings applied on the ship structure in determination of fatigue design life.\u0000 Since the application of North Atlantic ocean environmental condition is commonly used by major Classification societies, this condition might give the substantial deterioration on the fatigue design life of the ship that specially operate only in specific ocean area, i.e. South East Asia area. In this work, the wave scatter diagram of various environmental conditions is chosen and the statistical characteristic is compared. The wave load sequence that is used on the fatigue damage assessment are generated by using the concept of storm model, so that the changing nature of sea state could be emulated as in real ocean. Fatigue damage of a structure member of 220 meter Bulk Carriers is calculated based on various environmental conditions.","PeriodicalId":314553,"journal":{"name":"Volume 3: Structures, Safety, and Reliability","volume":"385 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":"131870350","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":"A Calculation Method for the Quasi-Stationary Pressure in Cabin Explosion With Venting","authors":"Pengduo Zhao, Haojie Wang, Zhipeng Du, Xiaobin Li","doi":"10.1115/omae2019-95776","DOIUrl":"https://doi.org/10.1115/omae2019-95776","url":null,"abstract":"\u0000 The explosion in the closed cabin will cause a sharp rise in cabin gas pressure, which will cause serious damage to the cabin structure. The quasi-stationary pressure, due to its long duration and large impulse, plays a major role in the destruction of the structural strength of the entire cabin. The venting holes on the transverse bulkheads can effectively guide the release of energy to other locations, reducing the damage to the cabin.\u0000 In this paper, the quasi-stationary pressure generated during cabin explosion with venting is studied. According to the conservation of mass and energy, the cabin explosion model with venting is transformed into an equivalent high pressure gas release model to simulate the initial instantaneous state of cabin explosion, and it is verified by finite element calculation that the two models are equivalent in predicting quasi-stationary pressure. The entire gas flow process during the exploding with venting holes is divided into two parts: the gas flow in the cabin to the venting hole and the venting hole to the atmosphere. An approximate analytical method for predicting quasi-stationary pressure generated during cabin explosion with venting is improved by using Bernoulli equation and isentropic compression formula of ideal gas, and the results of the improved calculation method are compared with the results obtained by the numerical simulation method to verify its validity.","PeriodicalId":314553,"journal":{"name":"Volume 3: Structures, Safety, and Reliability","volume":"6 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":"116532915","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":"Extreme Value Estimation of Mooring Lines Top Tension","authors":"M. L. Simão, P. Videiro, Mauro Costa de Oliveira, L. Sagrilo","doi":"10.1115/omae2019-96210","DOIUrl":"https://doi.org/10.1115/omae2019-96210","url":null,"abstract":"\u0000 It is known that the mooring system of floating platforms responds non-linearly to environmental loads. Even though the wave-frequency excitation can be assumed as a Gaussian process, the line tension generally is not a Gaussian process due to the second-order slow-drift floater motions and the nonlinearities of the system itself. Distinct short-term time-domain analyses with the same wave spectrum excitation, i.e., distinct realizations of the response process, lead to a set of distinct values for the simulated individual maximum observed line tensions. Therefore, the ideal practice for estimating extreme tension values should be to perform a sufficiently large number of independent simulations along with an extreme statistical analysis considering the sample of the maximum line tension identified in each simulation. However, this process can be very time-consuming and cumbersome for everyday design applications. In this paper, the short-term line tension is assumed to be a non-Gaussian ergodic process. The extreme tension is then estimated based on the peaks sample of just a single simulated tension time-history. A number of known probability distributions are fitted to the peaks of the time series and classic order statistics theory is applied to determine the most probable extreme line tension corresponding to a specified short-time period (3-h) in order to identify the one with best performance. The proposed probability distribution models for the tension peaks are the 3-parameter Weibull distribution, the Weibull distribution fitted to the tail of the data (Weibull-tail) and the Shifted Generalized Lognormal Distribution (SGLD). The estimated extreme values are also prone to uncertainties due to time-domain simulation details. The effects of the major parameters in the dynamic analysis, such as simulation length and discretization level of the wave spectrum, are therefore investigated using several simulated mooring line tension time-histories. Furthermore, the effect of correlation between consecutive line tension peaks in the extreme values estimation is investigated through a Nataf transformation-based model for joint probability distribution for the peaks and the one step Markov chain condition. It is shown that this latter consideration leads to extreme value estimates that are invariably smaller than those obtained by standard order statistics. These estimates are also shown to be closer to the extreme estimates directly obtained from a sample of largest values taken from several distinct numerical simulations. Numerical examples cover two study cases for mooring lines belonging to FPSO (Floating, Production, Storage and Offloading) units to be installed in Brazilian waters.","PeriodicalId":314553,"journal":{"name":"Volume 3: Structures, Safety, and Reliability","volume":"24 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":"130863660","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":"Impacts of Reliability on Operational Performance and Cost of Energy Evaluation of Multi-Megawatt, Far-Offshore Wind Turbines","authors":"C. Dao, B. Kazemtabrizi, C. Crabtree","doi":"10.1115/omae2019-95561","DOIUrl":"https://doi.org/10.1115/omae2019-95561","url":null,"abstract":"\u0000 Wind energy is growing at a fast pace around the world. According to a report published by WindEurope, 55% of total power capacity installations in the EU came from wind in 2017. In this context, offshore wind plays a decisive role, with countries such as the UK leading the development of large-scale offshore wind projects within Europe and around the world. It is essential that the cost of energy from offshore wind remains competitive with other sources of energy to encourage further investment in offshore wind developments. One way to maintain and further reduce the cost of offshore wind energy is to take advantage of economies of scale by increasing the megawatt ratings of offshore wind turbines. On the other hand, the operational expenditure of the turbines could also be reduced significantly. In this paper, we present a new integrated operation simulation framework for performance evaluation of multi-megawatt direct drive wind turbines suitable for use in far offshore wind farms. The operation simulation considers several essential wind turbine data such as component reliability, i.e. failure rates and downtimes per failure, historical wind speed, turbine information, and repair cost per failure to estimate the operational and economic performance of the wind turbine in its entire lifetime. In the proposed operation simulation, component reliability models and a wind power model are coupled together to simulate wind turbine operation over its entire lifetime using a time-sequential Monte Carlo simulation. Since the reliability data for large-scale offshore wind turbines are scarce and/or restricted to only direct stakeholders, a range of operational profiles for the turbines based on different level of reliability are simulated. In addition, the economic performance of the turbine is measured by defining an index for levelised cost of energy as a function of component reliability. In this way, the wind turbine reliability, power output, failure cost and levelised cost of energy are estimated under the variation of input reliability data. The results of this paper can inform wind turbine performance depending on the reliability of its components, and provide useful information for critical components identification and economic assessment of future far offshore wind turbines.","PeriodicalId":314553,"journal":{"name":"Volume 3: Structures, Safety, and Reliability","volume":"26 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":"125333044","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 Approach for Estimating the Corrosion Rates on Aging FPSO Hull Structures","authors":"Vicente d’Orema Albuquerque Larangeira, P. Videiro, José Alfredo Ferrari Júnior, L. Sagrilo","doi":"10.1115/omae2019-95067","DOIUrl":"https://doi.org/10.1115/omae2019-95067","url":null,"abstract":"\u0000 This paper presents a methodology to estimate the thickness loss on hulls of Floating, Production, Storage and Offloading (FPSO) platforms under general corrosion. The main purpose is to define characteristic corrosion rates for structural reassessment of the extension of life of FPSOs considering results of previous in-life inspections.\u0000 The steel wear generates sectional loss and capacity reduction, possibly leading to structural failure. Being capable of estimating FPSO’s plates and stiffeners thickness along the operational life would be a considerable safety improvement for the whole industry, benefiting operators and classifications societies.\u0000 During this research, different models were investigated to define the proposed methodology: (a) Model A (Garbatov and Soares [1,2]); (b) Model B (Melchers et al. [3–11] and, the one considered more appropriate to this study, Model C (Paik et al. [12,16]).\u0000 The proposed approach, based on Paik et al (2003), considers that the results of thickness loss readings in inspections during the operational life of the FPSO may be modeled by the Weibull model. Then, this model is applied to estimate the characteristic corrosion rate for the structural reassessment of FPSO extension life.\u0000 Results of the proposed methodology are presented for four structural components of a typical converted FPSO single hull in operation at Campos Basin, Brazil offshore.","PeriodicalId":314553,"journal":{"name":"Volume 3: Structures, Safety, and Reliability","volume":"2 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":"121622124","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 Arrow-Shaped Honeycomb Pedestal With Negative Poisson Ratio and its Impact Resistance","authors":"Haoran Wu, Xiao-Xuan Lin, Jie Zhang","doi":"10.1115/omae2019-95745","DOIUrl":"https://doi.org/10.1115/omae2019-95745","url":null,"abstract":"\u0000 The ship’s pedestal is the connection structure between the ship’s equipment and the hull, and is also the basis for the installation of the equipment. The pedestal bears both the static load generated by the weight of the equipment and the dynamic load generated during the operation of the equipment, and at the same time transmits the external load received by the hull to the equipment, and the load it bears is very complicated. If there is a problem with the pedestal in an impact environment, the accuracy of the system equipment will be affected, the system equipment will not work properly. Negative Poisson’s ration structures have a unique set of properties because of their tensile expansion, such as increased shear modulus, enhanced fracture toughness, better energy absorption and co-curvature. In recent years, the negative Poisson’s ration honeycomb structure has been applied to the pedestal of marine equipment, which demonstrates good vibration damping effect. However, the pedestal has two functions: vibration damping and impact resistance, there is not much research on the impact resistance of the pedestal. In this paper, an “arrow-shaped” honeycomb pedestal is taken as the research object. Firstly, the analytical expression of the Poisson’s ration of the honeycomb pedestal is derived theoretically and the influence of each parameter on the Poisson’s ration is analyzed. Secondly, the effect of Poisson’s ration on the impact resistance of the pedestal was analyzed by ensuring that the pedestal height was constant. It was found that with the reduction of Poisson’s ration, the impact resistance of the pedestal and the output impact environment of the pedestal panel were effectively optimized. Finally, by ensuring that the height of the pedestal is constant and the Poisson’s ration is the same, the influence of the number of honeycomb layers on the impact resistance of the pedestal is analyzed.","PeriodicalId":314553,"journal":{"name":"Volume 3: Structures, Safety, and Reliability","volume":"23 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":"131415602","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}