Dynamic design of ships

Research Project, 2017 – 2018

In order to develop ships for more efficient transport at sea, with reduced specific fuel consumption and emissions, the tendency is to design larger ships (IMO 2015). There is a big potential to develop ships for more efficient transport at sea by optimize the construction to reduce weight and steel to lower the cost for building and operate the ship. In this process it is of first importance to ensure that any changes in the construction is done in a secure way. The effect of less steel and changed construction on the ships damage tolerance against wind and wave loads, and the dynamic response of those external forces, has to be evaluated.

According to a study from IMO (IMO2009) the potential is a 2-20% reduction in greenhouse gases for an optimized hull construction and reduced weight. 

To ensure that legislations are fulfilled with respect to structural strength, seakeeping characteristics, environmental requirements and safety at sea more knowledge is required to understand how requirements and solutions affect the complex construction of the ship. Today there is a lack of guidelines and regulations which accounts for the dynamic loads on the ship when it is operating in wind and waves. Studies reports that ships of different types have increased problem due to wave loads leading to resonance (springing) or fading vibrations(whipping) in the hull beam. This has led to that ships have cracked and constructions have broken due to a combination of fatigue and exceedance of global longitudinal strength. A lack of basic understanding may lead to the opposite effect, i.e. the ships are designed to be oversized leading to higher weight and larger displacement, leading to unnecessarily high fuel consumption and increased environmental impact.

The project aims to conduct joint research and development of refined methods for dynamic design of ships, to increase the knowledge about how dynamic loads on ships affects the structural response.

The goals in this application are to:

· Develop a combined method and model testing setup in order to evaluate the response of the hull beam for a ship hull in waves.

· Evaluation of numerical methods for simulation of global and local structural response

· Validate model tests and numerical simulations against full scale sea trial and measurements

In this application partial funding is applied for the project. The project participators has the intention to apply for further funding in a joint application to Energimyndigheten this spring.

The development of methods and simulation models is essential together with the model tests and full scale sea trials to evaluate the validity of the quasistatic and dynamic analysis. The project will contribute to the international research at the leading edge led by the ISSC-ITTC committee (see the section “tidigare erfarenhet”) by proposing a rational and reliable methodology applicable when designing new ships and retrofitting.

By developing model test setup for testing of structural response in waves and refined simulation models the hope is that lighter, more energy efficient hull can be constructed, which reduces environmental impact and enhances the competitiveness of ship owners, shipyards and ship.

For the participants in the project knowledge will be accumulated that will strengthen national capacities in the field of dynamic design of ships, which is a strategically important area in the future, acknowledged by the international organizations ITTC and ISSC.