Experimentální studium mikrotrhlin v kompozitních materiálech při mechanickém zatěžování

Experimental Study of Micro-cracks in Composites under Mechanical Stress

Paper in proceedings (conference paper)

Mechanical stress of specimens results in generation of micro-cracks whose walls bear electric charges of opposite sign. The crack walls are executing damped oscillations thus giving rise to electric charge oscillations. The charge movement induces electric potentials in electrodes, which are applied to the specimen. These electric potentials are amplified to be subsequently processed in a PC. An acoustic emission signal, which is due to the crack generation, is measured at the same time. The acoustic and electromagnetic signals are shifted in time against each other in consequence of the different wave propagation velocities. The time shift is also influenced by the acoustic sensor’s distance from the crack location. Our measurements were carried out in EXTREN composite, a building industry material. The measurement results are in a good agreement with the current theory of electromagnetic emission from mechanically stressed materials.

Mechanical stress of specimens results in generation of micro-cracks whose walls bear electric charges of opposite sign. The crack walls are executing damped oscillations thus giving rise to electric charge oscillations. The charge movement induces electric potentials in electrodes, which are applied to the specimen. These electric potentials are amplified to be subsequently processed in a PC. An acoustic emission signal, which is due to the crack generation, is measured at the same time. The acoustic and electromagnetic signals are shifted in time against each other in consequence of the different wave propagation velocities. The time shift is also influenced by the acoustic sensor’s distance from the crack location. Our measurements were carried out in EXTREN composite, a building industry material. The measurement results are in a good agreement with the current theory of electromagnetic emission from mechanically stressed materials.

Kompozitní materiál, Mikrotrhliny, Elektrický náboj

Composites, Micro-cracks, Electric Charge

KOKTAVÝ, B., KOKTAVÝ, P., TOMEČEK, K.

2011

01.01.2004

Fakulta stavební VUT v Brně

Brno

80-7204-354-4

EXPERIMENT '04

209

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