Optimisation of passenger ship structures in concept design stage

ABSTRACT

This paper presents an optimization method for concept design state of passenger ship with focus on utilisation of efficient Finite Element Modelling, evolutionary optimisation algorithm and indirect constraint relaxation. The response is analysed using 3D coarse mesh global finite element (FE) model, where stiffened panels are modelled using equivalent single layer (ESL) elements and the primary stiffeners are modelled with offset beam elements. The simplifications on stiffened panels and beams enable exploration of design space without changing the FE-mesh. The strength is defined based on classification society rules. Local stress peaks are allowed to exceed the rule-based strength limits, i.e. stress constraints are relaxed indirectly. Instead of increasing the allowed stress levels, the amount of material exceeding strength criteria is utilised. Optimization is based on Particle Swarm Optimization (PSO) algorithm with objective to reduce steel weight. The results show that stress relaxation has significant effect on the obtained total mass.

KEYWORDS:

• Optimisation
• equivalent single layer (ESL) theory
• equivalent element
• particle swarm optimisation
• global finite element model
• passenger ship
• constraint relaxation

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes on contributors

Joni Raikunen is a structural analyst at Meyer Turku Oy.

Eero Avi is a postgraduate student at Aalto University and a structural analyst at Meyer Turku Oy.

Heikki Remes is an assistant professor at Aalto University.

Jani Romanoff is an associate professor at Aalto University.

Ingrit Lillemäe-Avi is a structural analyst at Meyer Turku Oy.

Ari Niemelä is the head of hull classification design, Meyer Turku Oy.

Additional information

Funding

The work was supported by Meyer Turku Oy. The financial support is gratefully appreciated.