Microstructural change in ice: I. Constant-deformation-rate tests under triaxial stress conditions

Abstract

Extensive damage to ice occurs during ice structure interaction by microcracking, recrystallization and melting. The objective of this work was to investigate this damage process under confined-stress conditions believed to be associated with impact zones that occur during ice–structure interaction. “Damage” refers to microstructural modification that causes deterioration of the mechanical properties. Prior experimental work has shown that a small amount of deformation causes permanent damage in ice, leading to enhanced creep rates during subsequent loading. To investigate this softening, freshwater granular ice was deformed under moderate confinement (20 MPa) at –10°C, at two rates which bracket ductile and brittle behavior (10−2 s−1 and 10−4 s−1). Samples were deformed to different levels of axial strain up to 28.8%. Thin sections were examined to assess the progressive changes in microstructure.Both grain-boundary and intra-granular cracking began at strains corresponding to the peak stress (1–2%) for tests at both strain rates. The peak stresses were 23.4 MPa for the tests at 10−2 s−1 and 9.8 MPa for the tests at 10−4 s−1. At strains of > 1–2%, dense clusters of intra-granular cracks began to develop in the samples tested at the higher rate. At the lower rate, dynamic recrystallization was apparently the dominant deformation mechanism beyond the peak stress. The average grain-size decreased strongly during the first few per cent strain and then maintained a relatively stable value.

The Dynamic Failure Behaviour of High-Pressure Zones during Medium-Scale Ice Indentation Tests

“…Tests using a spherical indenter provide valuable insight into the ice-crushing process, and the behaviour of a single hpz can be studied in detail using such tests. Failure within the hpzs is influenced by damage processes which typically include microcracking in zones of high shear and low confinement, as well as dynamic recrystallization and localized pressure melting in regions of high shear and high confinement [18][19][20]. Understanding how the hpzs scale is important in modelling the correlation of pressures during non-simultaneous failure of ice against different sizes of structures.…”

Laboratory Investigation on Mechanical Behavior of Artificial Ice under Triaxial Compression

“…The creep test is often used to investigate time-dependant deformation under any loading regime. An increase of compliance with an increase in confining pressure was reported in creep tests (Jones and Chew 1983;Melanson, et al, 1999;Barrette and Jordann, 2001). Due to time-dependant deformation mechanisms are thermally-activated, creep test can only be conducted at a temperature that is close to the melting point of the material, as is the case for most ice engineering applications.…”

Numerical Analysis of Iceberg Impact Interaction with Ship Stiffened Plates Considering Low-temperature Characteristics of Steel

“…Tsai-Wu 항복 함수 기반의 탄성-완전 소성 재료 모델을 제시하 였으며, 선측 및 선수부의 빙 충돌 해석을 통해 이 재료 모델의 유효성을 증명하였다. 이 외에도, Jia et al(2009), Gagnon(2011), Gao et al(2015) 최근의 구조물-빙 충격 상호작용의 수치적 연구 (Matsui et al, 2018;Yu et al, 2018;Zhu et al, 2018) 위해 Sammonds et al(1989), Gagnon and Gammon(1995), Melanson et al(1999) Gagnon and Gammon(1995)…”