Method and device for determining fracture depths by means of ultrasound

摘要

The invention relates to a method and a device for determining the depth of fractures in workpieces, components, installations, apparatuses and other objects, ultrasonic pulses being introduced into the object to be tested and being received, converted, amplified and evaluated after reaction with the fracture. In order to be able to determine the fracture depth by means of ultrasound even when the shape, width and inclination of the fracture are not known, and when an unknown medium is present in the fracture, both on the inside and on the outside and on nonaccessible sites, according to the invention the acoustic irradiation of the fracture is performed using a specific type of wave, and from the fracture display obtained the transfer function is determined as a function of the frequency by setting up an amplitude spectrum from which a determination is made of the transition frequency f@ (from reflection to scattering) from which the fracture depth is calculated with the aid of the sound velocity and a constant which depends on the selected type of wave. In the device, there is connected downstream of the receiver test head a receiving unit which consists of a demodulator fed by the transmitter, a narrow-band filter having a peak value meter, and two separate memories and a comparator connected to these.