Author(s): R. Gagnon; B. Quinton; S. L. Andrade
Linked Author(s):
Keywords: Ice impacts; Pressure sensing; Double-pendulum apparatus; Impact panel; Ice/liquid slurry layer
Abstract:
A series of ice impact experiments have been conducted using a large double-pendulum apparatus, and the results from one of the experiments are presented here. In former tests the apparatus was outfitted with novel high spatial and temporal resolution pressure-sensing technology, where a high-speed camera captured the pressure-distribution data at 500 images/s. In the present tests an array of five plug-type piezoelectric pressure sensors, mounted to a nominally-rigid impact panel, was used to capture pressure data from the central region of the ice contact area at an effective rate of 10,000 samples/s for each sensor. Consequently, the sensor array enabled temporal, and spatial (to a relatively-limited extent), tracking of ice spallation formation and hard-zone evolution with finer time-series resolution than previously. Single and multiple-sensor arrays of small pressure sensors have been incorporated into various moderate displacement-rate (centimeters per second) ice-indentation apparatus and higher rate (meters per second) ice impact apparatus in the past. The present tests are the first where an array of imbedded pressure sensors was used for impact tests where the loads generated were in the range associated with damage to real ship grillages. Pressure and load data from the former and present experiment are compared and discussed, and found to be generally in agreement. An unexpected result from the test was the observation, in the high-speed imaging record, of a thin plate of refrozen ice/liquid slurry following its formation and ejection from, along with other ice ejecta, the ice/panel contact zone. The slurry layer, which has been previously observed at smaller scales, is thought to be an important component of ice/structure interaction at various scales, and this observation is the first direct visual evidence of the layer at this intermediate scale.
Year: 2024