Electromagnetic Emission Signal Generated by a Moving Crack in Solids

Electromagnetic Emission Signal Generated by a Moving Crack in Solids

Paper in proceedings (conference paper)

When a stress is applied to the solids (rocks or tiles) cracks creation can be detected by signals of an acoustic and electromagnetic emission. The experimental study has been performed on rock samples. Two metallic layers have covered the tested devices to create metal-insulator-metal structure. During the process of the crack generation the electric charges appeared at the faces of the cracks. The electric dipole system is a source of voltage induced on metal electrodes. Using Shockley-Ramo theorem, the differential equation for induced voltage is derived. We found that voltage on measuring capacitor is directly proportional to the dipole width and its active area. The recorded electric signal is superposition of crack walls "self" vibration given by crack length and vibration due to an ultrasonic wave given by sample dimensions. The electromagnetic signal precedes the acoustic emission response and time delay corresponds to the difference of propagation velocities of sound and electromagnetic radiation in the sample. The simultaneous investigation of acoustic and electromagnetic emission signals enable us to localise the crack position in solids.

When a stress is applied to the solids (rocks or tiles) cracks creation can be detected by signals of an acoustic and electromagnetic emission. The experimental study has been performed on rock samples. Two metallic layers have covered the tested devices to create metal-insulator-metal structure. During the process of the crack generation the electric charges appeared at the faces of the cracks. The electric dipole system is a source of voltage induced on metal electrodes. Using Shockley-Ramo theorem, the differential equation for induced voltage is derived. We found that voltage on measuring capacitor is directly proportional to the dipole width and its active area. The recorded electric signal is superposition of crack walls "self" vibration given by crack length and vibration due to an ultrasonic wave given by sample dimensions. The electromagnetic signal precedes the acoustic emission response and time delay corresponds to the difference of propagation velocities of sound and electromagnetic radiation in the sample. The simultaneous investigation of acoustic and electromagnetic emission signals enable us to localise the crack position in solids.

Electromagnetic Emission, Acoustic Emission, Crack

Electromagnetic Emission, Acoustic Emission, Crack

KOKTAVÝ, P.; ŠIKULA, J.; KOKTAVÝ, B.

2011

01.01.2002

Ing. Zdeněk Novotný, CSc.

Brno

80-238-9094-8

Noise and Non-linearity Testing of Modern Electronic Components

134

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