Stiffness Adjustment of Surface-Piercing Hydrofoils Within Fluid-Structure Interaction

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

Projekt strukture i analiza čvrstoće palube za slijetanje helikoptera

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

Stiffness Adjustment of Surface-Piercing Hydrofoils Within Fluid-Structure Interaction

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

Structural Design of a Composite Trimaran

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

Savjetovanja o morskoj tehnologiji u Republici Hrvatskoj

This paper presents the history of the Conference on Marine Technology held so far in the Republic of Croatia – in memory of Zlatko Winkler, Fellow of the Croatian Academy of Sciences and Arts (HAZU). The contribution of the Conference to the scientific community is pointed out along with its genesis, aims, organization, realization, and future perspectives. The historical data regarding the number of participants and presented works is summarized for the first time, and the structure of current Committees is presented.U radu su sažeta sva dosadašnja Savjetovanja o morskoj tehnologiji održana u Republici Hrvatskoj – u spomen na akademika Zlatka Winklera. Opisuje se cjelokupna geneza Savjetovanja, od same početne ideje i svrhe pa do pripreme i realizacije svakog od devet održanih savjetovanja, kao i značajni momenti i odluke u razvoju Savjetovanja. Brojčani podaci karakteristični za svako pojedino Savjetovanje su prikazani tablično, kao i struktura posljednja dva Organizacijska i Izvršna odbora. Obzirom na prikazane podatke i širinu tematskih cjelina vezanih za morsku tehnologiju, za očekivati je daljnji razvoj Savjetovanja u budućnosti

Methodology for Optimal Mast and Standing Rigging Selection of a Racing Yacht Using AHP and FEM

The racing yacht design process, except the hull and appendages, involves the selection of sails, rigging and mast. Proper selection and scantling calculations of the mast and standing rigging is of crucial importance as it is the backbone and connection of sail driving load transferred to the hull. Optimal selection within a racing yacht is even more important because of the fact that such yachts are operated by professional crews that are capable to get out the maximum of the ship and its masts and rigging. Thus in this paper the authors present a novel methodology for the optimal selection of a mast and standing rigging based on the procedure in three main phases by using AHP method through the fi rst two phases and FEM analysis in the last one. The fi rst phase includes identifi cation of possible design solutions, while the second one searches for the best design confi guration and determines the stability of the chosen solution. The third phase is used for load calculations, scantlings determination, and fi nal approval of the project variables. The proposed methodology is applied and tested on the selection of mast and standing rigging of a 40-foot racing yacht

MULTI-OBJECTIVE STRUCTURAL OPTIMIZATION – A REVIEW OF THE GENETIC ALGORITHM METHODS

Mnogo je načina za poboljšanje brodske strukture, s ciljem zadovoljenja zahtjeva brodogradilišta i brodovlasnika. Načini se odnose na karakteristike brodske strukture, koje su u osnovi sukobljene na način da se poboljšanje jedne karakteristike ne može postići a da se ne pogorša neka druga. Te su karakteristike uobičajeno: troškovi, masa, pouzdanost, sigurnost, stabilitet. Cilj je pronalaženje kompromisa s obzirom na važnost pojedine karakteristike. U tom su smislu evolucijski algoritmi, kao optimizacijski alati, kod većine inženjerskih problema dokazali svoju valjanost, budući da uspješno upravljaju velikim brojem varijabli i ograničenja, a u posljednje vrijeme i funkcija cilja. Proces usavršavanja tih alata ostvaruje se hibridnim rješenjima koja spajaju najbolje od nekoliko različitih pristupa. Stvaranje jednog algoritma koji bi bio primjenjiv na sve probleme je nemoguće. U ovom je radu prikazano nekoliko važnijih pristupa i metoda genetskog algoritma s više funkcija cilja s ciljem usmjeravanja stručnjaka koji ulaze u područje strukturne optimizacije na one metode koje su dokazale svoju valjanost u praktičnim primjenama.There are numerous means of enhancing ship structure in an attempt to satisfy both the shipyard and the ship owner requirements. These means are addressed as a ship’s attributes and they are regularly contrary in meaning, such that the improvement in one cannot be achieved without making some other worse. Typically these are e.g. cost, weight, reliability, safety and stability, which can be minimized or maximized to improve the final design. A compromise obviously has to be made between them, depending upon the importance of each attribute. Evolutionary algorithms have proven their worthiness in a great variety of practical engineering problems, handling many variables, constraints and objectives. However, the need to improve them is always present. This has recently been done by hybridization, combining different approaches in order to get the best of them. To devise an algorithm which will be applicable to all problems is impossible. In this review, for the purpose of directing the experts entering in the field of structural optimization, only a few of the most important approaches and multi-objective algorithms have been presented