Simulation of the Temperature Distribution in Ship Structures for the Determination of Temperature- Dependent Material Properties

Several Arctic waters are no longer ice-covered throughout the year. As a result, the Northern Sea Routes are getting into the focus of the maritime industry [1]. In addition less ice coverage in other sea areas such as the Baltic Sea leads to increased shipping traffic in the winter season. This repeatedly leads to damages to ships when sailing in ice-covered waters, but also when colliding with ice floes and icebergs but also with ships, such as icebreakers, in convoys [2, 3]. It is of great importance for the structural simulation of these events to model the material properties of the ship structure under consideration of the environmental conditions. These material properties such as yield strength and tensile strength as well as fracture strain, however, are strongly influenced by the material temperature [4]. Therefore the question arises how cold a ship structure can actually become in winter and in arctic waters and how this affects the structural response in the event of a collision. In the rules and guidelines of the classification societies -60 °C can be found as the lowest temperature for material tests on steels used in shipbuilding [5]. This value corresponds well with different temperature measurements where extreme values below -50 °C were measured in the area of the Northern Sea Route [6, 7]. In contrast, liquid seawater cannot become colder than -2 °C [8]. If the interaction with ice is considered, the structural temperature in the waterline area is of particular interest. It is influenced by both water and air temperature. Therefore, the structure temperature is estimated by thermal simulations in order to determine suitable temperature depended material curves and to predict the influence on the structural response in the collision scenario.