Structural design of hatch cover for bulk carrier

Cilj ovog preddiplomskog rada je projektiranje konstrukcije grotlenog poklopca na poziciji oko glavnog rebra broda za prijevoz rasutog tereta (nosivosti oko 300 000 DWT) prema zajedničkim pravilima IACS Common Structural Rules for Bulk Carriers, July 2012. Za konstrukciju poklopca je bilo potrebno definirati broj i poziciju jakih nosača te orijentaciju i razmak sekundarnih ukrepa koji će rezultirati optimalnom topologijom s obzirom na ukupnu masu poklopca. U početnoj konceptualnoj fazi proveden je tablični proračun prema preskriptivnim Pravilima, različitih, proizvoljno odabranih varijanti topologija grotlenog poklopca koji je služio za odabir topologija za daljnju usporedbu. Osim tablične usporedbe napravljen je i algoritam za traženje optimalne topologije poklopca metodom izolirane grede prema pravilima IACS-CSR koristeći Excel Solver. Preliminarna faza sadrži izradu modela odabranih varijanti topologija poklopca sa grubom mrežom konačnih elemenata u računalnom programu MAESTRO. Na temelju rezultata analize provedeno je inicijalno dimenzioniranje konstrukcijskih elemenata, te naprezanja svedena na jednaku razinu radi usporedbe varijanti. U završnoj fazi su odabrane dvije najpovoljnije varijante topologija iz preliminarne faze te su za njih izrađeni modeli sa finom mrežom konačnih elemenata. Oba modela su modelirana u skladu sa zahtjevima Lloyd's Register (LR). Svi konstrukcijski elementi su redimenzionirani s obzirom na kriterije izvijanja i popuštanja prema pravilima IACS-CSR. Nakon usporedbe masa poklopaca je odabrana povoljnija topologija. Za nju je provedeno finalno dimenzioniranje, usklađivanje dimenzija jakih nosača te izrada tehničke dokumentacije.The objective of this thesis is structural design of a hatch cover, located around the midship area, for a bulk carrier (deadweight around 300 000 DWT) based on IACS Common Structural Rules for Bulk Carriers, July 2012. It was required to determine the number and position of primary supporting members, as well as the orientation and number of secondary stiffeners which will result in an optimal topology according to the total mass of the hatch cover. In the initial concept phase, a table calculation based on prescribed Rule calculation, of different, arbitrarily chosen topological variants of the hatch cover was conducted which served as the basis for further analysis. Besides the table comparison, an algorithm based on the isolated beam method according to IACS-CSR was also created for finding the optimal topology variant using the Excel Solver. Preliminary phase includes making coarse mesh finite element models of chosen topology variants using the computer program MAESTRO. Initial scantling determination of structural elements was based on analysis results and all stresses were reduced to the same levels for comparison. Two favorable topology variants from the preliminary phase were modeled with a fine mesh of finite elements. Both models comply with Lloyd’s Register assessment procedures. All structural elements were resized with respect to buckling and yielding criteria according to IACS-CSR. After comparing the total mass of the hatch covers, the most favorable topology variant was chosen. Final sizing of structural elements was conducted for that variant, as well as harmonizing the dimensions of primary supporting members and creating technical documentation