Session: 06-01-01 Computational Mechanics and Design Applications
Paper Number: 79485
79485 - "Probabilistic Design of Thin-Walled Cylindrical Structures for Application In Large Cargo Submarines "
Collapse failure is identified as the dominating failure mode of submarine pressure hulls owing to the large hydrostatic pressure which brings about a low collapse pressure capacity unless thick plates with closely spaced stiffeners are used. However, because cargo submarines require a high payload capacity to be economically attractive, an optimal design with low structural weight is vitally important. This makes thin-walled structures with a high strength-over-weight ratio favourable. Therefore, one crucial challenge relates to the research of large underwater cargo submarine concepts is to propose a cost-effective design for the collapse of the submarine pressure hulls. From experience, the collapse pressure capacity of thin-walled structures is highly sensitive to the geometric imperfections generated during manufacturing. To cover this, a common practice used by the design-by-rule approach is to introduce a very conservative safety factor. However, such an approach is not structurally efficient. In this paper, a probabilistic design approach for ring-stiffened cylindrical cargo submarine hull is proposed. Hulls with an 8500 mm median radius and wall thickness of 45 mm are used as examples. The shapes of the welding seams are considered. These pressure hulls are subjected to normal uniform external pressure. Initial imperfections are represented by the Fourier series. Using the Monte Carlo method, stochastic realisations of the imperfections are made, and the corresponding collapse pressures are calculated using finite element analysis. The collapse pressures are then collected and used to plot the cumulative distribution function (CDF). Finally, based on the desired failure probability, the collapse pressure capacity can be defined from the CDF. It is shown that the collapse pressure capacities calculated using probabilistic design are significantly higher than the design-by-rule method.
Presenting Author: Yucong Ma University of Stavanger
Authors:
Philip Lundberg Jamissen University of StavangerYucong Ma University of Stavanger
Yihan Xing University of Stavanger
"Probabilistic Design of Thin-Walled Cylindrical Structures for Application In Large Cargo Submarines "
Paper Type
Technical Paper Publication