International Shipbuilding Progress - Volume 66, issue 1

Authors: Frandoli, Paolo | Marinò, Alberto | Bucci, Vittorio

Article Type: Editorial

DOI: 10.3233/ISP-199000

Citation: International Shipbuilding Progress, vol. 66, no. 1, pp. 1-1, 2019

Authors: Piscopo, Vincenzo | Scamardella, Antonio

Article Type: Research Article

Abstract: The ultimate strength assessment of platings affected by pitting corrosion wastage is a basic issue for the scantling and design of ship structures. In the past, several nonlinear FE analyses were performed to investigate the incidence of pitting degree and corrosion depth on the ultimate strength of plate panels, with the main aim of providing some approximate formulations, useful at least in the preliminary project phase. Based on actual state of art, the main aim of current research is to provide an analytical formulation for the ultimate strength assessment of platings with random pitting corrosion wastage, by solving the Marguerre …non-linear governing differential equations for large deflection analysis of platings in the post-buckling regime. In this respect, a comparative analysis between the analytical solution and a series of FE results is preliminarily performed for uncorroded platings, combining different levels of initial geometrical imperfections and welding residual stresses. Subsequently, the comparative analysis is extended to platings affected by pitting corrosion wastage. Hence, different levels of pitting and corrosion intensity degrees are properly combined in order to investigate the goodness of the proposed analytical formulation. Show more

Keywords: Plating ultimate strength, Marguerre equations, pitting corrosion wastage, FE analysis

DOI: 10.3233/ISP-180251

Citation: International Shipbuilding Progress, vol. 66, no. 1, pp. 3-15, 2019

Authors: Corigliano, Pasqualino | Crupi, Vincenzo | Guglielmino, Eugenio

Article Type: Research Article

Abstract: Aluminum superstructures and steel hull connections are of fundamental importance in ships. This study regards the buckling analysis of explosion welded joints, made of three layers (ASTM A516 low carbon steel, pure aluminium, A5086 aluminium alloy) and used in ship structures. Tensile and compressive tests were carried out on explosion welded specimens. The Infrared Thermography was used to detect the superficial temperature of the specimen during the tensile test and three phases of the temperature evolution were observed. The Digital Image Correlation technique was applied during the tests for the detection of displacement and strain fields. A theoretical analysis, considering the …different materials was also performed for the analysis of buckling, which occurred during the compressive tests. Furthermore, a non-linear finite element analysis, considering the different mechanical properties of the explosive welded joint, was performed and was validated by means of the experimental results, obtained by the compressive tests. Show more

Keywords: Explosive welded joints, buckling, digital image correlation, infrared thermography, non-linear finite element analysis, ship structures

DOI: 10.3233/ISP-180252

Citation: International Shipbuilding Progress, vol. 66, no. 1, pp. 17-34, 2019

Authors: Nasso, Carlo | la Monaca, Ubaldo | Bertagna, Serena | Braidotti, Luca | Mauro, Francesco | Trincas, Giorgio | Marinó, Alberto | Bucci, Vittorio

Article Type: Research Article

Abstract: The continuous increasing attention to environmental sustainability and air pollution reduction for transport systems, requires not only to adopt new technologies and innovative solutions to limit vehicles emissions, but also to study their life-cycle. In case of inland navigation, the operation close to urban areas or in natural protected environments requires the adoption of a green propulsion. Moreover, especially for small crafts, the problem of ship disposal at the end of life is of high importance, even once plastic materials should be disposed, due to high costs and process complexities. For such a reason the design of a new generation …green passenger craft requires the analysis and knowledge of multiple engineering fields, that could lead to a fast and successful design only by means of an integrated approach. In the present work, this approach will be applied to the design of a passenger craft, adopting an hybrid electric powering system and build with strip planking process for wooden ships. The description of the construction process will be here described together with the on-board electric power system. The integrated approach allowed also to directly evaluate the vessel operative profile and asses whether the vessel could perform a Zero Emission Mode navigation. Show more

Keywords: Green shipbuilding, integrated design, environmental sustainability, strip planking, inland navigation

DOI: 10.3233/ISP-180254

Citation: International Shipbuilding Progress, vol. 66, no. 1, pp. 35-55, 2019

Authors: Mauro, Francesco | Braidotti, Luca | la Monaca, Ubaldo | Nabergoj, Radoslav

Article Type: Research Article

Abstract: For the dimensioning of particular structures like stingers or generic tubular elements for offshore industry, it is usual to predict the extreme values of wave induced loads. Both for model test and calculations, the traditionally adopted methods of analysis are based on Weibull distribution. The necessity to investigate severe sea state conditions together with the increased complexity of the structure is an evident source of non-linearities in the exciting force peaks distribution. In the specific, the adoption of a standard Weibull approach is not indicated for accurately predict the extreme loads. The adoption of more accurate distributions suitable to capture …peaks non-linearity will ensure to overcome or capture possible multi-modal behaviour of the considered population. These enhanced techniques can be used not only for model test results analysis, but also for results coming from preliminary hydrodynamic calculations (CFD). In the present work, two different methodologies based on Mixed Weibull and Generalised Pareto distributions will be applied to the results obtained for a stinger geometry, where Morison theory is adopted to evaluate wave loads considering shield effects between the single tubular elements. Show more

Keywords: Extreme loads, extreme value theory, generalised Pareto distribution, mixed Weibull distribution, Morison equations

DOI: 10.3233/ISP-180256

Citation: International Shipbuilding Progress, vol. 66, no. 1, pp. 57-76, 2019

Authors: Morgut, Mitja | Jošt, Dragica | Škerlavaj, Aljaž | Nobile, Enrico | Contento, Giorgio | Pigazzini, Riccardo | Puzzer, Thomas | Martini, Simone

Article Type: Research Article

Abstract: The numerical predictions of a cavitating model scale propeller working in uniform and oblique flow conditions are presented. The cavitating phenomena are numerically reproduced using a homogeneous (mixture) model where three previously calibrated mass transfer models are alternatively used to model the mass transfer rate. The turbulence effect is modelled using the Reynolds Averaged Navier Stokes (RANS) approach. The simulations are performed using an open source solver. The numerical results are compared with available experimental data. For a quantitative comparison the propeller thrust is considered, while for a qualitative comparison, snapshots of cavitation patterns are shown. The thrust values obtained …with the three different mass transfer models are very close to each other, however differences in the predicted cavitation patterns are observed. Moreover, some discrepancies between the numerical results and experimental data are reported. Show more

Keywords: Propeller, cavitation, uniform inflow, oblique flow, RANS

DOI: 10.3233/ISP-180257

Citation: International Shipbuilding Progress, vol. 66, no. 1, pp. 77-90, 2019

Authors: Vergassola, Gianmarco | Boote, Dario | Ricci, Lisa

Article Type: Research Article

Abstract: The growing increase in length of super and megayachts has driven structural designers to adopt longitudinal layouts as a main point in the structural scantlings. By the way, the optimization of weights, strength, deformations and dynamic behaviour has to be evaluated separately for each new unit because of the particular and unique characteristics of each vessel. For this evaluation, especially for what the dynamic behaviour of ribbed plates is concerned, the use of numerical software based on the Finite Element Method is widely used since the early design stages in order to highlight benefits and weaknesses of a particular …structural design. In this paper, two different structural layouts of megayacht decks have been studied and tested by using a FE software: the first one has been created with longitudinal and transversal stiffeners with the same cross section. In the second layout, transversal stiffeners are smaller in dimension but with lower span. The comparison has been carried out making reference to maximum strengths, deformations and dynamic behaviour. This work, starting from an initial lay out obtained by a CS rule approach, made it possible to converge to an optimal structural configuration, at least for what the starting geometries are concerned. Show more

Keywords: Megayacht, deck structural scantling, FEM, vibration analysis

DOI: 10.3233/ISP-180260

Citation: International Shipbuilding Progress, vol. 66, no. 1, pp. 91-110, 2019