Malitckii Evgenii, Remes Heikki, Lehto Pauli, Bossuyt Sven
Department of Mechanical Engineering, Aalto University School of Engineering;
Department of Mechanical Engineering, Aalto University School of Engineering.
J Vis Exp. 2019 Jan 16(143). doi: 10.3791/59134.
A novel measurement approach is used to reveal the cumulative deformation field at a sub-grain level and to study the influence of microstructure on the growth of microstructurally small fatigue cracks. The proposed strain field analysis methodology is based on the use of a unique pattering technique with a characteristic speckle size of approximately 10 µm. The developed methodology is applied to study the small fatigue crack behavior in body centered cubic (bcc) Fe-Cr ferritic stainless steel with a relatively large grain size allowing a high spatial measurement accuracy at the sub-grain level. This methodology allows the measurement of small fatigue crack growth retardation events and associated intermittent shear strain localization zones ahead of the crack tip. In addition, this can be correlated with the grain orientation and size. Thus, the developed methodology can provide a deeper fundamental understanding of the small fatigue crack growth behavior, required for the development of robust theoretical models for the small fatigue crack propagation in polycrystalline materials.
一种新颖的测量方法被用于揭示亚晶粒水平的累积变形场，并研究微观结构对微观结构小疲劳裂纹扩展的影响。所提出的应变场分析方法基于一种独特的图案化技术，其特征散斑尺寸约为10微米。所开发的方法被应用于研究体心立方（bcc）Fe-Cr铁素体不锈钢中的小疲劳裂纹行为，该不锈钢具有相对较大的晶粒尺寸，从而允许在亚晶粒水平实现高空间测量精度。这种方法能够测量小疲劳裂纹扩展延迟事件以及裂纹尖端前方相关的间歇性剪切应变局部化区域。此外，这可以与晶粒取向和尺寸相关联。因此，所开发的方法能够对小疲劳裂纹扩展行为提供更深入的基本理解，这对于开发多晶材料中小疲劳裂纹扩展的稳健理论模型是必需的。
