Research On Strength Assessment Of Polar Ship Under Ice Load

According to the American National Snow and Ice Data Center,Arctic sea ice extent has been shrinking at a rate of3.5%per decade. And25%of undiscovered petroleum resources are assumed in the Arctic areas.Driven by soaring oil price and increasing oil consumption, oilexplorations in the Arctic and subarctic areas become more frequent inrecent years. Furthermore, the shrinking of Arctic sea ice extent hasprovided an enhanced opportunity in the creation of new routes forcommercial shipping. As a result, more and more large ice-going ships ofnovel designs enter the region with harsh environment where the industryhas limited experience, which presents new challenges for designers,operators and regulators. This thesis mainly deals with the ice loadcalculation and polar ship strength assessment under ice load, and themain content of this thesis is listed as follows:1. The properties of sea ice and the influence of sea ice on polarships are introduced, then the theories and methods to calculate ice loadare concluded; 2. With the help of commercial software MATLAB, ice load iscalculated by using limit energy mechanism, and the ice load of one Articship is calculated under different ice shapes;3. Since the allowable plastic deformation of ship structure isdifferent in different ice class rules, this thesis uses the limit load conceptto assess the structural safety of polar ships, and then proposes a suitablelimit load criterion for polar ships;4. Since nonlinear finite element analysis needs a lot of calculationtime, plastic formulation is introduced to reduce the need to use nonlinearfinite element analysis. Combining plastic formulation and the suitablelimit load criterion, a rapid assessment procedure of polar ship structureunder ice load is proposed.