Effects of prestrain on the ductile-to-brittle transition of ice

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• 作者：Scott A. Snyder ; ^{scott.snyder@dartmouth.edu" class="auth_mail" title="E-mail the corresponding author} ; Erland M. Schulson ; Carl E. Renshaw
• 关键词：Ice ; Brittle-to-ductile transition ; Creep ; Crack propagation ; Mechanical behavior
• 刊名：Acta Materialia
• 出版年：2016
• 出版时间：15 April 2016
• 年：2016
• 卷：108
• 期：Complete
• 页码：110-127
• 全文大小：4277 K

文摘

The ductile-to-brittle transition was investigated in prestrained columnar ice at −10 °C. Laboratory-grown specimens of freshwater and saline ice were prestrained under uniaxial across-column compression (to levels from ε_p = 0.003 to ε_p = 0.20, at constant strain rates in the ductile regime) and likewise reloaded (at rates from 1 × 10⁻⁶s⁻¹ to 3 × 10⁻²s⁻¹). Prestrain caused solid-state recrystallization as well as damage in the form of non-propagating microcracks. The ductile-to-brittle transition strain rate ${\dot{\epsilon }}_{\text{D}/\text{B}}$ increased by a factor of 3–10 after prestrain of ε_p = 0.035 in both freshwater and saline ice, compared to that of initially undamaged ice of the same type. Additional prestrain had little further effect on ${\dot{\epsilon }}_{\text{D}/\text{B}}$. The results are interpreted within the framework of a model (proposed by Schulson, 1990, and Renshaw and Schulson, 2001) that predicts the transition strain rate based on the micromechanical boundary between creep and fracture processes. Model parameters primarily affected by prestrain were the power-law creep coefficient B (more so than the creep exponent n), Young's modulus E and, by extension, the fracture toughness K_Ic.