Bogdan Szturomski

Modelling the structural response to underwater explosions (UNDEX) remains one of the most demanding fields of simulation engineering due to the limited feasibility of experimental validation. To address this, the present study compares two approaches for assessing the shock resistance of naval...

The demand for energy media and information exchange in the 21st century is increasing. Numerous natural gas pipelines, power lines, telecommunications, and optical fibres run through the seabed. Wind formations are being built in the Baltic Sea. These installations, like any technical device,...

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 fluid-structure 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+.

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...

Andrzej Grządziela, Radosław Kiciński, Bogdan Szturomski, Paweł Piskur; Review, pp. 92-102 Download

This paper presents the results of a static and dynamic tensile test of an Al7.5Mg aluminium alloy taken from round bars made in the technology of hydrostatic extrusion. It is planned to use the Al7.5Mg aluminium alloy for joining riveted structures. Based on the obtained results, the nominal and true characteristics of the Al7.5Mg aluminium alloy, depending on the strain rate in the range from 0 to 2000 s⁻¹, were developed. The failure criterion for tension was determined. The material characteristics were approximated by the Johnson–Cook equation, which can be used in CAE (computer-aided engineering) programs to simulate the impact processes. FEM (finite element method) simulation of the impact of the hammer on the part of the riveted aircraft structure was performed. The FEM simulation results were compared with the experimental results on a drop hammer to verify the material model. The following results were obtained: yield strength R_e = 395.3 MPa; strength limit R_m = 523.1 MPa at deformation 0.067; Young’s modulus E = 7.9 × 10⁴ MPa. The AL7.5Mg alloy after hydro-extrusion has favourable plastic and strength properties.

TThe aim of the work is to present a newly developed stand and methodology of accelerated tests of fatigue strength of flexible propellers and fins. The paper presents the design and concepts of the measuring elements used in the research. Test methodology and water stressing were devel-oped. The mechanical properties of the following materials were presented: Arnitel EL-550 and QUEO 8230 with the addition of PP / EVA 50/50 (polypropylene / ethylene-vinyl acetate) - in the proportion of 70/30 (QUEO 8230 / additive). The constructed test stand and a new method of fa-tigue testing of biomimetic fins made it possible to determine the number of fin movement cy-cles under a given load, which may facilitate the determination of a warranty for a newly intro-duced product. The current consumption by the fin drive and video monitoring allowed for the selection of the range of the number of movement cycles and the determination of the moment of fatigue cracks until the fin structure loses its capacity. During the analysis, the test results showed that the fins made of Arnitel EL-550 did not show changes in the measured values of the current and the force generated by the fin. For a fin made of QUEO 8230, at 35,000 cycles, there is a decrease in the current and force consumed, which indicates the initiation of fatigue damage to the fin. The performed tests can be the basis for the development of standards for the fatigue strength of flexible propellers.

The paper shows research on a closed fermentation chamber (CFC) that is an element of the Biogas Combined Heat and Power Plant located in the Gdansk East Sewage Treatment Plant. This tank is mounted as an above-ground cylinder-shaped structure covered with a cone-shaped roof. Corrosion and leaks appeared in the tanks during many years of operation. In this work, it was decided to investigate their cause and propose a method of counteracting them. The article presents the research on the influence of individual operational and environmental loads on the stress distributions in the tank structure. Numerical simulations using the Finite Element Method were carried out for shell and solid models. Moreover, the stress distributions in cylindrical steel tanks were compared depending on the shape of the chamber top. The research results allowed us to identify the design errors of the closed fermentation chambers. It finds out that the connection of the cylindrical part of the tank with the conical roof requires reinforcement. A tank repair technology using Belzona composites was proposed to modify the joint geometry. A simulation was performed, taking into account the proposed repair technology. Its results showed a reduction of stresses compared to the state before repair by 19%.

Recently, there have been reports of disasters related to the disappearance of submarines. One of the potential causes of disasters is the ship’s descent to the so-called critical depth and its subsequent implosion. However, the occurrence of the submarine implosion phenomenon may be difficult to achieve. This is due to the presence of hydraulic fittings and other more susceptible hull components. The article presents an analysis of the strength of a fragment of the submarine’s hull, modelled on Kobben-class ships, to demonstrate the possibility of an implosion. Furthermore, the construction of submarines was presented, and phenomena related to the strength of submarine hulls using FEM were discussed.

Due to the modernization of warships, it was necessary to carry out strength calculations for the newly assembled devices, for which there were no detailed technical requirements. The authors try to present and harmonize the requirements for naval military structures. The lack of experimental verification of newly built systems was indicated. Therefore the finite element method was used to determine the durability of the critical design elements. There is no explicit reference load in the literature, so the authors present a general solution to one of the worst cases. The work presents the cannon structure elements exposed to damage during the underwater explosion load, using the proposed methodology. The proposed method is sufficient to calculate individual ship cases. However, in the case of hull strength analysis, more complex algorithms should be used.