The nanoscale crack propagation behavior in the presence of nonlinear disturbance strains is studied by using the phase-field-crystal method. The influences of amplitude A and frequency ω on fracture mode and crack growth are discussed. The simulation results suggest that the disturbance strains can make fracture mode change between brittle fracture and ductile fracture. When amplitude A is large, increasing frequency ω will lead to the brittle-to-ductile transition (BDT). Further increasing ω can make ductile-to-brittle transition (DBT) happen. Meanwhile, the value of A can influence the critical frequencies for BDT and DBT. Crack growth is also affected by the disturbance strains. When ω is small, increasing ω or A can accelerate crack growth. When ω is large enough, increasing A will retard it. Through this work, we provide a new way to effectively explore the nanoscale mechanism and behavior of crack propagation.

中文翻译：

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非线性扰动应变下纳米二维晶格裂纹扩展行为的相场晶体研究

采用相-场-晶体方法研究了非线性扰动应变下的纳米级裂纹扩展行为。讨论了振幅A和频率ω对断裂模式和裂纹扩展的影响。模拟结果表明，扰动应变可以使断裂模式在脆性断裂和韧性断裂之间发生变化。当振幅A较大时，增加频率ω将导致脆韧转变（BDT）。进一步增加ω可以使韧性到脆性转变 (DBT) 发生。同时，A的值可以影响 BDT 和 DBT 的临界频率。裂纹扩展也受扰动应变的影响。当ω较小时，增大ω或A可以加速裂纹扩展。当ω足够大时，增加A会延迟它。通过这项工作，我们提供了一种有效探索裂纹扩展的纳米级机制和行为的新方法。