Ice crushing tests with variable structural flexibility

To learn more on ice crushing phenomena against a compliant stiffened plate structure, near full-scale ice crushing tests were conducted in Aker Arctic test basin with a 1:3 scaled model. The dimensions of the to be crushed ice sheet and the stiffened plate were chosen to present a full size ship or offshore structure steel plating which are designed to withstand the crushing loads of 60 cm thick level ice. A major difference to the crushing tests published earlier in literature was that the compliance of one stiffener could be adjusted. The instrumentation in the plate included both strain gauges for load paths from the plate to the stiffeners and a large tactile sensor for detailed direct crushing pressure distribution measurement. In order to have repeatable and homogeneous model ice properties the ice blocks were manufactured by snow ice technique with low salinity water impregnation under vacuum in the mould. Altogether 22 ice blocks were crushed with different ice velocities and plate compliancy. The well-known line like contact prevailed in continuous crushing. The test data indicates that the crushing load distribution is independent from the underlying plate stiffness distribution and no higher crushing pressure at the location of stiffeners was found.

Research Highlights
► Model tests in 1:3 scale provided new understanding on ice crushing behaviour.
► Snow impregnated with water under vacuum produced repeatable homogenous model ice.
► Crushing pressure distribution on plate was independent of stiffeners or their flexibility.
► Line like contact prevailed in continuous crushing with mountain ridge shape solid ice edge.
► Solid ice stress build up phase is mainly ductile in continuous brittle crushing.