Fatigue Crack Imaging of V-Notched Specimen using X-Ray Tomography

The aim of this research is to investigate fatigue damage in a V-notched specimen machined from ZK60-T5 magnesium extrusion. V-notched Specimens were loaded at different stress amplitude to cover life range between 17×10^3 and 13×10^6 cycles. One sample was selected for x-ray tomographic analysis, therefore, the test on this sample was interrupted 14 times to perform x-ray imaging. Segmentation analysis of these images suggests an exponential crack area growth with cycling. Strain energy density approach was used successfully to consolidate fatigue life data of un-notched and V-notched specimens in a single narrow scatter band.本研究旨在探究由ZK60-T5镁合金挤压材加工而成的V形缺口试样（V-notched specimen）的疲劳损伤特性。实验对该类V形缺口试样施加不同应力幅的循环载荷，以覆盖17×10³至13×10⁶次循环的寿命区间。选取其中一个试样开展X射线断层扫描分析（X-ray tomographic analysis），因此该试样的测试被中断14次以完成X射线成像。对所得图像的分割分析表明，裂纹面积随循环加载次数呈指数级增长。本研究采用应变能密度方法（strain energy density approach），成功将无缺口试样与V形缺口试样的疲劳寿命数据整合至单一窄离散带中。