Analysis of laboratory growler impact tests

Growler impact tests have been performed in IOT's lee Tank facility. Free-floating parallelepiped-shaped growlers (small glacial ice masses) were impacted with a heavy apparatus (i.e. impact plate) designed to simulate a ship bow. Impacts were conducted at speeds ranging from 0.2 to 3.0 m/s, at three growler orientations, and at impact plate angles of 45degrees, 30degrees, and 15degrees. The impact plate measured forces and incorporated a new panel for pressure measurements. Peak loads increased linearly with impactor speed, and increased with impact plate angle. Growler orientation affected peak impact loads, where the greatest values occurred when the long axis of the growler was normal to the impact plate surface. The duration of the impacts for a particular growler was approximately constant regardless of the test parameters. Thin sections of ice from the zones of impact showed the ice to be relatively intact. Data and thin section observations from a few crushing tests in an MTS machine on samples of the same iceberg ice corroborated with pressure data and thin sections from the growler impact tests. The growlers appeared to be resilient to impacts and could withstand many impacts without significant damage to the bulk ice. (C) 2003 Elsevier B.V. All rights reserved.