Wyniki wyszukiwania - Biblioteka Nauki

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Mechanical properties of welded joints of 1.3964 steel for Computer Aided Engineering (CAE) purposes

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Kiciński R. , Jurczak W.

Scientific Journal of Polish Naval Academy

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2020

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tom R. 61 nr 1-2 (220/221)

15--28

EN

The article presents the study of mechanical properties of welded steel from which the hull of a modern mine destroyer was made. Keeping the tightness of ship compartments during operation depends on the strength of these joints. The results of testing the mechanical properties of 1.3964 steel and its welded joints subjected to a static tensile test were presented, and a Johnson – Cook material model was proposed. The material model can be used in CAE (Computer Aided Engineering) simulations related to hull strength analysis.

PL

W artykule przedstawiono wyniki badań właściwości mechanicznych połączeń spawanych stali, z której zostało wykonane poszycie kadłuba współczesnego niszczyciela min. Od wytrzymałości tych połączeń zależy utrzymanie szczelności przedziałów okrętowych w czasie eksploatacji. Zaprezentowano wyniki badań właściwości mechanicznych stali 1.3964 i jej połączeń spawanych poddanych statycznej próbie rozciągania oraz zaproponowano model materiałowy Johnson – Cook. Model materiałowy może zostać wykorzystany w symulacji komputerowej CAE obciążenia kadłuba okrętu wykonanego z badanej stali.

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Determination of material characteristics necessary for modelling of marine structures exposed to small-calibre bullet

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Kiciński R. , Szturomski B. , Jurczak W.

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tom Vol. 26, No. 4

105--111

EN

The article presents the results of tests of impact properties of steel 1.3964 used on the construction of modern mine destroyers. Ships of this type, like any other military unit, may be exposed to small-calibre projectiles. Firing can be done, for example, from aircraft, drones or pirate units. The thickness of the plates used in the ship’s construction does not guarantee effective resistance to the projectile calibre 7.62 mm for all compartments of such ships. Thus, it is possible to modify the existing structure or apply additional solutions that will ensure a certain level of ballistic resistance. Solutions of this type are necessary in order to maintain the stability and buoyancy of the ship at the current level. During the tests, a stress-strain curve for steel 1.3964 was obtained, then the Johnson-Cook plasticity and damage model was proposed, which was used in the FEM simulation. The task was modelled as non-linear considering the deformation of both the sample and the projectile. The simulation was prepared in the CAE program, and then verified by an experiment on the shooting range. The results were presented in the form of diagrams and deformation figures, and were compared with photographs of samples and velocities after the specimen.

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Accelerations Caused by Underwater Explosions on the Naval Gun Foundation

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Szturomski B. , Kiciński R. , Milewski S.

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tom Vol. 18, no 1

129--141

EN

The manuscript analyzes the impact of a non-contact underwater explosion on the foundation of a 35 mm naval cannon mounted on board a Project 258 minehunter. The finite element method was used to complete the task. Cole's empirical formulas were used to describe the distribution of the pressure wave from the explosion of the TNT charge in water as a function of distance, time, and mass. The hull geometry was reflected based on technical documentation as a shell structure reinforced with beam-bar elements. Devices with large weights were represented as rigid bodies. Simplifications were used to minimize the number of degrees of freedom. The construction of ship's hull is made of non-magnetic austenitic steel. The dynamic characteristics of this steel were determined based on static and dynamic tensile tests. The Johnson-Cook constitutive model was used to describe the material properties of steel. As part of the work, the impact resistance study of marine structures was presented, how it is defined by the existing regulations in the Polish Navy was considered, and the scope of their applicability was given. The scientific innovation of the presented work consists of checking and specifying the guidelines for designing and constructing warships.

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Experimental validation of an FEM model based on lifting theory applied to propeller design software

70%

Grządziela A. , Kraskowski M. , Król P. , Szturomski B. , Kiciński R.

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tom nr 2

67--76

PL

In the process of designing a marine propeller, hydroelasticity effects are neglected in most cases, due to the negligible influence of the blade’s deformation on its hydrodynamic characteristics. However, there are cases where the impact of hydroelasticity is crucial, for example in the case of high skew-back propellers or heavy-loaded composite propellers. Furthermore, the importance of composite propellers is growing due to their wide range of application, for instance in naval ships and unmanned vehicles. Although structural models and two-way fluid-structure interactions are implemented in most commercial CFD solvers, their relevance to the design process is severely limited due to the high computational cost for a single iteration. An effective solution would therefore be to implement a two-way fluidstructure interaction model in the lifting surface software, which is commonly accepted as a design tool due to its relatively low computational time and its applicability to multi-criteria optimisation. This paper presents the results of hydrodynamic analyses of an elastic propeller carried out using in-house software based on the lifting surface flow model, and extended with the FEM model for the blade structure. The results are compared with experimental measurements and computational analyses with the commercial RANS solver STAR-CCM+.