航空

发动机--核心机的压气机、燃烧室、高低压涡轮交界处的损坏；航空发动机工作在高温、高压、高速的环境中，因此高温、高压、高速部件也会发生疲劳损坏和失效，这些部件不易拆卸，无法直接目视检查。因此，这些部件的检测和监控必须依靠内窥镜检测技术。(叶片的裂缝和损坏、叶片与机壳之间的间隙大小等）。

Case
Blade cracks usually appear as jagged, thin, black lines with sharp ends. The shape of the cracks will not change when the light intensity or angle is changed, and they will show characteristics such as depth and shadow. The continuous expansion of the cracks will eventually lead to the fracture of the components due to aging.

Notch A sharp surface depression at a corner or end caused by pressure or impact from a sharp-edged foreign object. Notches can cause stress concentration and lead to cracking. Usually, notches on compressor blades can cause blade fracture.

A depression in a smooth surface caused by pressure or impact from a blunt, smooth external object.

Bending refers to a change in the shape or profile of a blade, usually as a result of forces acting on one side.