Aker Arctic has finished work on the new hull rules for the Finnish-Swedish Ice Class Rules

The final report for the HULLFEM projects has been published by the Winter Navigation Research Board. In these projects, a new direct calculation method for the hull part of the Finnish-Swedish Ice Class Rules (FSICR) was developed.

The project work included various tasks:

Research: The underlying basic research was carried out and a method was selected, leveraging the extensive research into linear and non-linear finite element analysis of ice strengthened vessels made earlier at Aker Arctic. More details in the article: Nonlinear analysis tool benefits high ice-class vessels

Calibration: Aker Arctic refined the method by a series of calibration studies, which were conducted to align the new rules so that they result in an equal level of strength as the current rules.

Testing: The new rules were extensively tested on a wide variety of vessel designs typical of Baltic Sea trade.

Finally, a rule draft was written based on the research findings and circulated within the Classification Societies and IACS Hull Panel. After receiving comments, the final rule draft was created and will be adopted into the next version of the FSICR as an alternative to the current prescriptive method.

The new rules are based on the use of the non-linear finite element method, which allows accurate assessment of the structure both before and after yielding. This allows for direct connection between the analysis criteria and the desired outcome, which is that the permanent deformations from ice navigation in normal service remain small, and that the structure has sufficient reserve capacity for ensuring safe behaviour in accidental overload scenarios.

Unlike the current rules, which have a strict set of requirements for structural arrangement (such as minimum thicknesses, use of brackets and lugs, etc.), the new rules allow much greater design freedom. This enables the designers and shipyards to achieve an equivalent level of safety with structures that are easier and more economical to build. In the best-case scenario, significant savings in material usage can be achieved.

The final report of the HULLFEM project, together with the draft of the new rules, can be downloaded from the Traficom website

There was a presentation on the new rules at Aker Arctic´s seminar on March 6. The presentation can be found here: Development of new finite element guidelines for hull design in the Finnish-Swedish Ice Class Rules