Partial safety factor approach to the design of submarine pressure hulls using nonlinear finite element analysis

Journal article (2012)

Authors

J.R. Mackay Computational Design and Mechanics - Mechanical, Maritime and Materials Engineering
A. van Keulen Computational Design and Mechanics - Mechanical, Maritime and Materials Engineering
Research Group
Computational Design and Mechanics (Mechanical, Maritime and Materials Engineering) (TU Delft)
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Published Date

2012

Language

English

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Faculty

Mechanical, Maritime and Materials Engineering

Department

Precision and Microsystems Engineering

Research Group

Computational Design and Mechanics

Abstract

A framework for the design of submarine pressure hulls using nonlinear finite element (FE) analysis is presented in order to improve upon the conventional analytical-empirical design procedure. A numerical methodology is established that allows the collapse pressure of a hull to be predicted with controlled accuracy. The methodology is characterized by quasi-static incremental analysis, including material and geometric nonlinearities, of FE models constructed from shell elements. The numerical methodology is used with ANSYS to predict the results of 47 collapse experiments on small-scale ring-stiffened cylinders representative of submarine hulls. A probabilistic analysis is applied to the experimental- numerical comparisons in order to estimate the accuracy of the FE methodology and derive a partial safety factor (PSF) for design. It is demonstrated that a high level of accuracy, within 10% with 95% confidence, can be achieved if the prescribed FE methodology is followed. Furthermore, it is shown that the PSF for design does not need to be very large, even if a high degree of statistical confidence is built in. The designer can be 99.5% confident that the FE error has been accounted for by dividing the predicted collapse pressure by a PSF=1.134.

Keywords: Submarine pressure hull; Shell buckling; Collapse; Nonlinear finite element analysis; Design; Partial safety factor; Verification and validation.