Design of ship structures by means of non-linear programming techniques

Article type: Research Article

Authors: Moe, Johannes

Affiliations: Department of Ship Structures, The Technical University of Norway, Trondheim

Abstract: The sequential unconstrained minimization technique (SUMT) [10] has been used rather extensively in conjunction with cost and weight minimization of ship structures. In practical design problems the number of free variables easily becomes high and the structural analyses may also become complex. and time consuming. Large computer times are a consequence. This paper discusses various methods by which the required number of redesigns during the search for optimum as well as the computer work involved in each such redesign may be reduced. Approximate behaviour and constraint models in terms of simple polynomials have been used with considerable success and may be combined with an extrapolation technique that allows one to reduce significantly the number of response surfaces. In this manner the required computer time may be reduced to only a fraction of that previously experienced. A few examples of typical applications to practical ship design problems are presented, viz.: a.Minimum cost design of a typical tank section of an oil-tanker.b.Minimum cost design of the midship section of a car-carrier.c.Minimum weight design of grillages and transverse frames of tankers. The tanker design program is presently used as a preliminary design tool in one of the major Norwegian shipyards. It produces designs which comply with the rules of the Norwegian Ship Classification Society. A detailed cost model has been developed in close cooperation with the shipyard.

DOI: 10.3233/ISP-1970-1718701

Journal: International Shipbuilding Progress, vol. 17, no. 187, pp. 69-86, 1970