Structural Design of 38m Special Purpose Vessel in Aluminium Alloy

Abstract

The design of aluminium hull structure must satisfy strength, weight and productivity requirements. Since these requirements often conflict each other, there are a number of possible designs. This thesis reports the investigation of this process which includes below stages:

• Preliminary design of the vessel is executed such as general arrangement and hull form design, capacity planning, stability analysis, hull resistance prediction, etc. At this stage, the general arrangement is generated by considering the customer requirements. Then the hull form is designed by Maxsurf software by taking into account service performance. Stability calculations are performed by Hydromax software and submitted to representative of the customer and Classification Society to demonstrate that the vessel has stability in accordance with requirements of Classification Society and Flag Authority and at any case in accordance with IMO Resolution A749 (18). Hull resistance prediction is made by Savitsky method, afterwards final data on performance is confirmed by CFD calculations based on relative displacement between the agreed configurations. • The structural design of the vessel is satisfied with the rules and regulations of RINA (Registro Italiano Navale) for aluminium alloy High-Speed Craft. Longitudinal strength calculations are, as a rule, is carried out at the midship section and the scantlings of hull structures (plating, stiffeners, and primary supporting members) are determined. Buckling strength calculations are made for some critical members such as plating and primary members of bottom and deck structures by taking into account critical buckling stresses defined by rules. • Direct finite element analysis of main machinery foundations which have significant influence on structure is performed. Due to there is not any remarkable rules for aluminium alloy structured engine foundations, this kind of analysis was unavoidable. This analysis is performed by ANSYS Mechanical software. The results of FEA are examined for deflection and stress distribution and these are compared with permissible values imposed by rules.