The recent disastrous experience of the Costa Concordia ship as it collided with rocks has provoked much concern and discussion about safety on the seas. SAGE has freed access to these two relevant articles from this journal ‘Automatic collision avoidance of ships’ and ‘A procedure to optimize ship side structures for crashworthiness’.
The first considers automatic simulation of ship maneuvering to achieve effective safe paths on the seas and the second explores ways to optimize a conceptual ship side structure for crashworthiness with the aim of attempting to protect against rupture.
Automatic collision avoidance of ships
One of the key elements in automatic simulation of ship manoeuvring in confined waterways is route finding and collision avoidance. This paper presents a new practical method of automatic trajectory planning and collision avoidance based on an artificial potential field and speed vector. Collision prevention regulations and international navigational rules have been incorporated into the algorithm. The algorithm is fairly straightforward and simple to implement, but has been shown to be effective in finding safe paths for all ships concerned in complex situations. The method has been applied to some typical test cases and the results are very encouraging.
A procedure to optimize ship side structures for crashworthiness
This paper presents a procedure to optimize a conceptual ship side structure from a crashworthiness point of view. As an example, this procedure is presented for a chemical or product tanker. A particle swarm optimization algorithm is used for the procedure. The classification society compliance of the conceptual design is checked through service loads that are applied to the ship’s hull girder according to Det Norske Veritas. The collision simulations to assess the crashworthiness are carried out with the non-linear finite element solver LS-DYNA. An element length-dependent constant-strain failure criterion is chosen to simulate rupture. A numerical simulation of a stiffened plate serves to validate the material relation until failure. This material relation and failure definition makes possible an accurate prediction of the structural energy absorbed until inner plate rupture. The procedure is adjustable and applicable to other ship types and scenarios.
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Xue, Y., Lee, B., & Han, D. (2009). Automatic collision avoidance of ships Proceedings of the Institution of Mechanical Engineers, Part M: Journal of Engineering for the Maritime Environment, 223 (1), 33-46 DOI: 10.1243/14750902JEME123
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Ehlers, S. (2010). A procedure to optimize ship side structures for crashworthiness Proceedings of the Institution of Mechanical Engineers, Part M: Journal of Engineering for the Maritime Environment, 224 (1), 1-11 DOI: 10.1243/14750902JEME179