This work presents a new ultrasonic fatigue testing device for studying the initiation and propagation mechanisms of internal microstructurally short fatigue cracks using in situ synchrotron tomography. Its principle is described as well as the method used for automatically detecting crack initiation and its subsequent growth. To promote internal crack initiation, specimens containing internal casting defects were tested between the high cycle and very high cycle fatigue regimes (107-109 cycles). Preliminary results show the ability of this new device to initiate an internal microstructurally short crack in a reasonable testing time and monitor its growth.

中文翻译：

---

用于内部裂纹萌生和扩展的 3D 表征的原位同步加速器超声疲劳测试装置

这项工作提出了一种新的超声疲劳测试设备，用于使用原位同步辐射断层扫描研究内部微观结构短疲劳裂纹的萌生和扩展机制。描述了其原理以及用于自动检测裂纹萌生及其后续扩展的方法。为了促进内部裂纹萌生，在高周疲劳状态和极高周疲劳状态（107-109 次循环）之间测试了含有内部铸造缺陷的试样。初步结果表明，这种新装置能够在合理的测试时间内引发内部微观结构短裂纹并监测其生长。