A large double-pendulum device to study load, pressure distribution and structure damage during ice impact tests in the lab

• Main Authors: Gagnon, Robert, Daley, Claude, Colbourne, Bruce
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2015
• Subjects: Arctic
• Online Access: https://nrc-publications.canada.ca/eng/view/accepted/?id=8ab2ac1f-fd6f-49c1-9691-4f3003654309; https://nrc-publications.canada.ca/eng/view/object/?id=8ab2ac1f-fd6f-49c1-9691-4f3003654309; https://nrc-publications.canada.ca/fra/voir/objet/?id=8ab2ac1f-fd6f-49c1-9691-4f3003654309

The design and functioning of a new impact device is described, where its eventual intended use is the study of damage associated with pressure distributions arising from ice impacts on ships. The large apparatus is a double-pendulum type device that is capable of achieving fairly high impact energies and velocities while remaining relatively ‘compact’ with respect to the confines of the laboratory space that is available. For example, at a drop angle of 35o from vertical for each pendulum the impact energy and relative velocity are ~ 31 kJ and 5.32 m/s respectively. Conical-shaped ice samples, one meter in diameter are held in a cylindrical ice holder that attaches to one arm of the double pendulum. For one type of test a unique instrumented panel (Impact Module), that records load and high spatial resolution pressure distribution during impacts, attaches to the opposite pendulum arm. For another test type the Impact Module is replaced by ship grillage (full-scale or reduced scale) so that ice impact tests can be performed that cause damage to the grillage. The pendulum arms are designed in a manner such that no rotation of the colliding masses occurs during tests. The effective masses of the colliding objects can be adjusted by adding or removing heavy metal plates. Similarly, the drop angles of the pendulum arms can be adjusted to achieve a range of impact velocities. These two adjustable features enable a variety of impact velocities and energies to be obtainable and allow for some degree of parameter-based study where either velocity or energy is fixed while the other is varied. To date a number of tests have been performed involving ice impacts on the Impact Module. Some representative sensor data that includes a few examples of the ice pressure distribution from one test are presented. Peer reviewed: Yes NRC publication: Yes