Pal G. Bergan

On the potential of computational methods and numerical simulation in ice mechanics

This paper deals with the challenge of developing better methods and tools for analysing interaction between sea ice and structures and, in particular, to be able to calculate ice loads on these structures. Ice loads have traditionally been estimated using empirical data and engineering judgment. However, it is believed that computational mechanics and advanced computer simulations of ice-structure interaction can play an important role in developing safer and more efficient structures, especially for irregular structural configurations. The paper explains the complexity of ice as a material in computational mechanics terms. Some key words here are large displacements and deformations, multi-body contact mechanics, instabilities, multi-phase materials, inelasticity, time dependency and creep, thermal effects, fracture and crushing, and multi-scale effects. The paper points towards the use of advanced methods like ALE formulations, mesh-less methods, particle methods, XFEM, and multi-domain formulations in order to deal with these challenges. Some examples involving numerical simulation of interaction and loads between level sea ice and offshore structures are presented. It is concluded that computational mechanics may prove to become a very useful tool for analysing structures in ice; however, much research is still needed to achieve satisfactory reliability and versatility of these methods.

Design of a prismatic pressure vessel with internal X-beam structures for application in ships

ABSTRACT This research proposed a prismatic pressure vessel for gas-fuel storage on a gas-fuelled ship. The prismatic pressure vessel consisted of flat-plated shells, stiffeners, and beam structures. According to the design principle of pressure vessels, the beam structures were designed to receive tensile stresses generated from the internal pressure. International regulations and a finite element analysis were considered for the design, strength calculations, fatigue assessments, plastic collapse, and thermal effects. A case study in which the prismatic pressure vessel was applied as a gas-fuel tank to provide ship propulsion on a crude-oil tanker was performed. Nine per cent nickel steel was used to be applicable for cryogenic service. Several design loadings were considered to evaluate the design feasibility of the pressure vessel. The computational analysis results indicated that the prismatic pressure vessel satisfied the design regulations and should be applicable for use as a gas-fuel storage tank for ships.