Vorrichtung zur beruehrungslosen Erfassung eines Rissstarts bei einer Bruchmechanikprobe

A device for the contactless detection of initial crack formation (5) in a rupture mechanics sample (2) has a measuring device in which the sample (2) can be subjected to a load test by a loading element and a sensor (6, 10, 12) arranged at a predefined distance from the sample (2); the sensor can be connected to an analysis circuit (19). The sensor (6, 10, 12) comprises at least one capacitive sensor plate (7, 7') connected to an impedance converter (12) located in the direct vicinity of the sensor plate (7, 7'). One capacitive sensor plate (7) is connected to the complementary sensor plate (7') or tied to ground via a drainage resistor (10). The electric fields (8) emitted by the sample (2), when initial crack formation (5) occurs or by an existing crack (4) is expanded, are recorded by the sensor plate and transferred to an analyzer (19) via the impedance converter (12). It is therefore possible to detect fracturing and deformation of all fracture samples (2) reliably and to a high degree of sensitivity irrespective of material.