Masuda Kenichi, Ishihara Sotomi, Oguma Noriyasu
Department of Mechanical Engineering, University of Toyama, Gofuku 3190, Toyama 930-8555, Japan.
National Institute of Technology, Toyama College, Toyama 939-8630, Japan.
Materials (Basel). 2021 Jan 31;14(3):664. doi: 10.3390/ma14030664.
Fatigue crack growth experiments are performed using A7075-T6 compact tension (CT) specimens with various thicknesses (1-21 mm). The stress intensity factor at the crack opening level K is measured, and the effects of and the stress intensity factor range ΔK on K are investigated. In addition, the change in K value due to specimen surface removal is investigated. Furthermore, we clarify that the radius of curvature of the leading edge of the fatigue crack decreases as becomes thinner. Using the three-dimensional elastoplastic finite element method, the amount of plastic lateral contraction (depression depth ) at the crack tip after fatigue loading is calculated quantitatively. The following main experimental results are obtained: In the region where ΔK is 5 MPam or higher, the rate of fatigue crack growth da/dN at a constant ΔK value increases as increases from 1 to 11 mm. The da/dN between = 11 and 21 mm is the same. Meanwhile, in the region where ΔK is less than 5 MPam, the effect of on da/dN is not observed. The effects of and ΔK on the da/dN-ΔK relationship are considered physically and quantitatively based on .
使用不同厚度（1 - 21毫米）的A7075 - T6紧凑拉伸（CT）试样进行疲劳裂纹扩展实验。测量裂纹开口水平K处的应力强度因子，并研究 和应力强度因子范围ΔK对K的影响。此外，研究了由于试样表面去除导致的K值变化。此外，我们阐明了疲劳裂纹前缘的曲率半径随着 变薄而减小。使用三维弹塑性有限元方法，定量计算了疲劳加载后裂纹尖端处的塑性横向收缩量（凹陷深度 ）。获得了以下主要实验结果：在ΔK为5 MPam或更高的区域中，在恒定ΔK值下，疲劳裂纹扩展速率da/dN随着 从1毫米增加到11毫米而增加。 = 11毫米和21毫米之间的da/dN相同。同时，在ΔK小于5 MPam的区域中，未观察到 对da/dN的影响。基于 从物理和定量角度考虑了 和ΔK对da/dN - ΔK关系的影响。
