Abstract Large scale laboratory experiments on size and rate effects on the fracture of warm columnar freshwater ice have been conducted with floating edge-cracked rectangular plates loaded at the crack mouth. The largest test plate size had dimensions of 19.5m x 36m. The overall crack-parallel dimension covered a size range of 1 : 39 , possibly the largest for ice tested under laboratory conditions. The loading rates applied led to test durations from fewer than 2 seconds to more than 1000 seconds, leading to an elastic response at the highest rates to a viscoelastic response at the lower rates. Methods for both the linear elastic fracture mechanics (LEFM) and a non-linear viscoelastic fictitious crack model (VFCM) were derived to analyze the data and calculate values for the apparent fracture toughness, crack opening displacement, stress-separation curve, fracture energy, and size of the process zone near a crack tip. Issues of notch sensitivity and minimum size requirements for polycrystalline homogeneity were addressed. Both size and rate effects were observed, as well as how these two factors are interrelated in the fracture of columnar freshwater ice. There was a size effect at low rates but no size effect at high rates. There was a rate effect for the larger test sizes but a weaker or no rate effect for the smallest test size.

中文翻译：

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温暖的 S2 柱状淡水冰的破裂：尺寸和速率效应

摘要 对暖柱状淡水冰破裂的尺寸和速率效应进行了大规模实验室实验，在裂缝口处加载浮动边缘裂纹矩形板。最大的测试板尺寸为 19.5mx 36m。整体裂纹平行尺寸覆盖的尺寸范围为 1:39，可能是在实验室条件下测试的冰的最大尺寸。施加的加载速率导致测试持续时间从少于 2 秒到超过 1000 秒，导致最高速率下的弹性响应到较低速率下的粘弹性响应。推导出线性弹性断裂力学 (LEFM) 和非线性粘弹性虚拟裂纹模型 (VFCM) 的方法来分析数据并计算表观断裂韧性、裂纹张开位移、应力-分离曲线、断裂能和裂纹尖端附近加工区的大小。解决了多晶同质性的缺口敏感性和最小尺寸要求的问题。观察到尺寸和速率效应，以及这两个因素在柱状淡水冰的破裂中如何相互关联。在低利率下有规模效应，但在高利率下没有规模效应。较大的测试规模有速率效应，但最小测试规模的速率效应较弱或没有。在低利率下有规模效应，但在高利率下没有规模效应。较大的测试规模有速率效应，但最小测试规模的速率效应较弱或没有。在低利率下有规模效应，但在高利率下没有规模效应。较大的测试规模有速率效应，但最小测试规模的速率效应较弱或没有。