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Vorrichtung zur beruehrungslosen Erfassung eines Rissstarts bei einer Bruchmechanikprobe

Device for the contactless detection of initial crack formation in a rupture mechanics sample
 
: Winkler, S.

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Frontpage ()

DE 1989-1608 U: 19890213
DE 1990-4004171 A: 19900211
DE 4004171 C2: 19930325
G01N0003
German
Patent, Electronic Publication
Fraunhofer IWM ()

Abstract
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.

: http://publica.fraunhofer.de/documents/PX-40834.html