The issue of determining the reliability of the hulls of inland and river-sea-going vessels after a known number of years of operation under given condition is considered. It is accepted that fault detection of a ship’s hull is a survey, measurement and evaluation of defects in each element of the ship’s hull in order to establish the methods and scope of repairs that ensure its reliable operation until the next regular survey under specified operating conditions. It is shown that the volume of residual thicknesses can be significantly reduced using the statistical data on wear rates presented in the Rules of the Russian River Register. At the same time, the reduction in the scope of measuring the parameters of defects retains the probability of detecting all defects of the hull elements to the level of 0.95, and the probability of failure-free operation of the hull until the next survey, after the elimination of the identified defects will be at least 0.95. A form of table for processing the values of the residual thicknesses of all elements in the inspection report and instructions for filling it out are given. Explanations for using the results of measurements and calculations at determining the technical condition of certain elements in the group and the ship’s hull as a whole are given. The last column of the table indicates the method of eliminating the defect of an element and groups of elements, and in the conclusion of the inspection report, the method of repair and its scope for the entire hull of the ship providing a suitable assessment of the condition after repair are indicated. The main advantage of this paper, in difference from the previous studies of the authors in this area, is that user-friendly (the designer of the defect report tables) nomograms, which allow you to reduce the number of measurements of the residual thicknesses of hull structure elements in the online mode, have been created. The performed study, allowing you to reduce the number of measurements while guaranteeing the reliable operation of the ship’s hull, will let the shipowner to reduce the cost of repair work by reducing the number of days of ship standing on the slipway (in the dock). In addition, the ship repair company will be able to free up its production facilities for the purpose of their subsequent loading with other ship repair or shipbuilding orders, which will increase the efficiency of their activities.
Reliability of a vessel hull that has total deflection or kink is discussed in the paper. This hull defect may cause the sudden failure regardless of ship service life. There are no allowable values of characteristics (maximum deflection point) for this defect. There are no statistical data either, indicating the eventual increment of the deflection point, leading to the absence of the possibility to evaluate the hull reliability by this parameter. However, it is known that the presence of this defect causes the emergence of additional bending factor and the change of safety factor coefficient, influencing the allowable values of deck and bottom residual thickness. The residual thickness changes, depending on their operation time, are given in the rules of Russian River Register (RRR) and Russian Maritime Register of Shipping. Besides, these rules contain the allowable values of deck and bottom residual thickness. On the basis of the above, the dependencies for determining the possibility of failures emergence in terms of the average residual thickness of sheets in the link group due to the total deflection of the hull are offered. The condition according to which the average residual thickness of sheets in the links group is less than the allowable value established by the RRR Rules for a ship hull without common deformations is taken for a failure. The dependencies to calculate the decks' or bottoms' working area loss in the presence of deflection/kink given value are suggested. That allows calculating the amendment for permissible value of the average residual thickness of sheets. To evaluate the deformed hull reliability, the method of maximum deflection/ kink point determination plays an important role. The complexity of the task consists in the assignment of the residual deflection from the total one. A patent describing the residual deflected hull axis determination method, taking into account its curvature on the separate areas had been obtained by the authors of the paper. Based on this method, the dependencies to determine the maximum residual deflection/kink are offered. Thus, the opportunity to evaluate the reliability of the deformed hull depending on a given number of years of the vessel operation emerges.Keywords: reliability, allowable wear, residual total deflection/kink, the deviation of the normal to the surface from the vertical, curvature of the plot. For citation: Baryshnikov, Sergei O., Tatyana O. Karklina, and Valentin B.Chistov. "Reliability of ships hulls with over allresidual deformations." Vestnik Gosudarstvennogo universiteta morskogo i rechnogo flota imeni admirala S. O. Makarova 11.3 (2019): 519-533.Рассматривается надежность корпуса судна, имеющего общий прогиб или перегиб. Данный дефект корпуса может вызывать появление внезапного отказа независимо от продолжительности эксплуатации судна. Для этого дефекта отсутствуют допускаемые значения его основной характеристики (максимальной стрелки прогиба), а также отсутствуют статистические данные увеличения стрелки прогиба со временем, что...
The research is execute on the example of the main gate of the upper head of the locks No. 25-26 of the Saratov Hydraulic project of the Federal State-Funded Institution «Administration of the Volga Basin». Follows from results of earlier executed researches that the main destructive processes of aging reducing technical condition of gate and locks of navigable hydraulic engineering constructions are corrosion and corrosion and fatigue damages of their elements which realization is establish on separate elements of the studied metalwork. Use as the diagnostic parameter of size of corrosion wear of elements at high degree of roughness of their surface because of impossibility of his measurement with a necessary accuracy and lack of correlation at this operational phase of a metal construction with process of corrosion and fatigue process of the damage defining actual state of gate is incorrect. In process, growth of size corrosion wear elements the deflection gate which is the integrated indicator characterizing their elastic deformation will increase. The provide value of the allowed deflection of lifting and lowering gate under a pressure can't be considered now as the indicator correlating with change of a condition of their elements in time. The possibility of use of the provide value of an admissible deflection of gate as the diagnostic parameter of their technical condition is considered. Analytical evaluation of change of size of a deflection of lifting-gate from a hydrostatic pressure at various values of corrosion wear of their elements is execute. The discrepancy of the standard allowed values of a deflection of the lower girder of gate to the size of corrosion damage of their power elements is established. The field of possible realization of process of corrosion fatigue damage of power elements of the considered metalwork is define. The results presented in work can be used for correction of the established criteria values of indicators of safety for the considered metalwork of gate. The stated technique of check of a possibility of use of an indicator of a deflection of the lower crossbar of lifting-gate under a pressure as the diagnostic parameter of their technical condition can be used when checking efficiency of other diagnostic indicators of elements regulated by the specifications and technical documentation of the mechanical equipment of navigable hydraulic engineering constructions both operated, and designed.
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