Suchergebnisse

This paper presents results from numerical analysis of the fluid and structure interaction of two different hydrofoil models, Model 1 and Model 2. Analyzes were performed with stainless steel, aluminium and composite materials for Model 1, and Model 2 was created from composite with aluminium reinforcement. Models were analyzed for three different angles of attack (10, 20, 30 degrees) and for each angle three different speeds were tested (2, 4, 6 m/s). At first, the whole set of analysis was run for entirely submerged hydrofoils and later on for immersed hydrofoils to the draft h. Described numerical analysis was performed in order to adjust stiffens of hydrofoils based on different operational loads. Two-way fluid-structure interaction analysis was used which combines FEM and CFD solvers. Presented results are based on 44 analysis with which all planned conditions of hydrofoil operation were tested. Numerical analysis showed a correlation between stiffens of material i.e. structural response and hydrodynamic loading. Besides mentioned, based on analysis of Model 2 future prediction are given in a way of hydrofoil design or particularly placement for hydrofoils reinforcement.

This paper presents a project of a composite trimaran structure, designed and built for competing at the Hydro Contest 2016 competition at Geneva Lake. Concept of the contest is to raise the awareness of tomorrow's engineers, industrialists, opinion leaders and the public of what is at stake with regard to energy efficiency in the sea transportation of goods and passengers. In addition, to be the laboratory of tomorrow's boats, particularly enabling the most innovative ideas to be developed in collaboration with the industrial partners. Designed boats must have technological innovations enabling them to achieve the most efficient use of energy. Therefore, the goal was to design, construct lightweight structure, within simple closed rules, with a satisfactory stiffens, and strength as well as to strive for more efficient transport, which means higher speed with minimal energy consumption. An analysis of project variants was made with regard to the hull shape, material, and technology of the fabrication and for the adopted variant, a computer structure model was developed, and the FEA was carried out. The structure is divided into three main sections analysed individually: hulls, front wing and rear wing along with rudder. Calculation was made for the worst load case, i.e. mass transfer, while wings were analysed at the highest advancing speed. The boat has structurally met all requirements since there were no structural problems in testing and competing.

Paluba ili platforma za slijetanje helikoptera je za većinu trgovačkih, putničkih i posebice specijalnih tipova brodova (offshore, istraživački) od velike važnosti, kako za komunikaciju tako i za moguće hitne
situacije. Navedeno naročito dolazi do izražaj kod brodova koji se bave složenim offshore operacijama u teškim vremenskim prilikama i stanjima mora. Uvodno su prikazane vrste i pregled projektnih parametara platforme za slijetanje helikoptera. Za odabrani tip istraživačkog broda napravljen je projekt strukture, računalni model i analiza čvrstoće. Korištena su pravila i propisi klasifikacijskog društva American Bureau of Shipping za određivanje minimalnih strukturnih dimenzija, kao i za definiranje projektnih stanja opterećenja, te konačno kriterija za potvrdu projekta. Za izradu računalnog modela i analizu strukture metodom konačnih elemenata korišten je 3D CAD programski paket Inventor. Definirani su najgori slučajevi opterećenja, te su na osnovi izvršene analize usvojene konačne dimenzije strukture.

With the aim of improving the environmental sustainability in the field of maritime transport and with special reference to multimodality and 'green' solutions for coastal transport, within the METRO project (Maritime Environment-friendly TRanspOrt systems), funded under the Interreg VA CBC Programme Italy-Croatia, a project of a hybrid Ro-Pax medium range ferry for coastal navigation in the Adriatic area is developed. The paper presents a part of the conceptual design for the assessment of the global hull structure strength, which is not common for this phase of the project, and that is the structural analysis of the complete ship. For this purpose, a detailed computer model of the geometry of the whole ship was made, which includes all primary and basic secondary structural elements, with the aim that such a model can serve later as a good basis for classification and workshop documentation production during contract phase. Additionally, a preliminary calculation of the scantlings of the complete ship was performed according to BV rules and regulations using the MARS2000 software package, with regard to bending and buckling. Loads were modeled according to real conditions for two unfavorable loading conditions, and static linear analysis was performed using the LS-DYNA software package. The global analysis of bending strength in still water could reveal problematic areas in the structure.

Composite materials are in use in the shipbuilding industry for a long period of time. Composites appear in vast number of fibre – matrix combinations and can be produced with several different production processes. Due to the specific nature of the composite material structure, the selection of the production process and the limitations in the quality control procedures, composite materials will always be subject to defects and imperfections which may, under certain circumstances, lead to the appearance and propagation of cracks. The size and the shape of the crack, the load type and the stress field in the material surrounding the crack will be crucial for crack growth and crack propagation. This paper reviews the composite material damage processes especially relevant for shipbuilding. The basic principles of composite material fracture mechanics are briefly explained, and finally, mechanisms responsible for the development of damage and fracture of composite materials are presented. This paper has emerged from the need to summarize information about composite material fracture and failure mechanisms and modes relevant for the shipbuilding industry.

The calculation of shear forces and bending moments are the basis of every ship design documentation. It is essential for determining the strength of the ship and the reliability of the structure itself. Nowadays, due to a sheer volume of data, this calculation is performed exclusively with the help of specialized software packages. Such shear force and bending moment curves can often be obtained within the software packages specially designed for checking the ship's design according to specific classification societies' rules. Usually, they already have built-in formulas and guidelines to execute that task properly. However, such software packages often do not meet all the end user's needs. For example, for the initial project stage, special software packages with the functionality of easy designing of a ship form are usually used, while the aforementioned packages are used in later design stages when performing stability and structure checks. This transition often requires converting files into the appropriate type from one software to another. The Rhinoceros program is widespread in the shipbuilding profession, and it is often used in the initial stages of the project. It also allows automation of the process with the help of integrated scripts. Therefore, the authors have decided to examine the possibility of using Python scripts within the Rhinoceros software package. The mentioned script will calculate the transverse forces and bending moment based on the previously modelled hull.

Deformations and stresses during the transport and manipulation of large ship blocks within ship assembly and erection stages are a common and significant issue, particularly in the construction of complex ships and variable production mix, as is the case in many European shipyards. The appearance of deformations and stresses requires adequate addressing with the aim of their early determination and reduction with a goal to reduce a significant number of working hours spent for the large ship blocks transport preparation, for the transport and manipulation itself, and for the reworks. The appearance of residual stress in blocks that are not adequately addressed can be an issue in the exploitation, reducing the quality and ship service life. In this paper, the authors present the procedure of determining deformations and stresses in the large ship block. The procedure is based on computer modelling and numerical analysis of the selected ship block. Various scenarios of the foundations' arrangement and the arrangement of the transport hooks were analysed, and the optimal solutions were proposed. The procedure allows determining deformations and stresses at an early stage of ship technology design to define the adequate preparation for ship block foundations layout, transportation and manipulation before production starts. In doing so, it is expected to reduce deformations and stresses itself, necessary working hours for block accommodation, transportation and manipulation and to reduce repair works. Such procedure application is expected to raise the efficiency of the overall ship production process and the quality of the final product. Finally, further research is proposed regarding various scenarios of technological procedures, ship blocks structures or used materials.

The paper presents an analysis of the basic parameters of Ro-Pax ships and double-ended ferries. The study was carried out within the framework of the project METRO (Maritime Environment-friendly TRanspOrt systems), funded from 2014-2020 Interreg V-A Italy-Croatia CBC Programme. The aim of the project is an improvement of the environmental sustainability in the field of maritime transport, with particular emphasis on multimodality and "green" solutions for the coastal transport. The specific focus is on touristic connections in the North Adriatic area. One of the project goals is a development of short-medium range hybrid ships and of concern are Ro-Pax ships and double-ended ferries, which are the most common ship types for coastal shipping in the Adriatic area. Two extensive databases were created encompassing a large number of ferries that operate in Europe, by one for each ship type. The databases will serve as basis for the preliminary design of the new hybrid Ro-Pax ship and double-ended ferry.