How does ultrasound work in crack detection?

Ultrasound works in crack detection by emitting high-frequency sound waves into a material. These waves travel through the material and reflect off internal features, including cracks or voids. When a crack is present, it causes a change in the velocity and amplitude of the reflected waves, which can be detected and analyzed. By interpreting these reflections, technicians can assess the size and location of the cracks within the material.