Analýza vzniku mikrotrhlin v mechanicky zatěžovaných kompozitních materiálech

Analysis of mechanical load induced micro-crack generation in composites

conference paper

Czech

The formation of a crack is accompanied by the generation electromagnetic field, whose fundamental parameters were evaluated for a dipole model of the respective source. A differential equation was developed and solved to describe the transformation of the field parameters into an electric signal, provided capacitive and inductive sensors are used. In the next stage, an analysis of spurious external electromagnetic and acoustic fields was carried out and measures to suppress their effects were designed. The issue of amplifying extremely low electromagnetic signals generated during the crack formation was dealt with, too. The mentioned analyses resulted in the design of a method to detect and evaluate electromagnetic emission (EME) signals and acoustic emission (AE) signals, which accompany mechanical stressing of materials and structures. Based on the results of such analyses, an automated double-channel measuring apparatus for both signal data acquisition, saving and processing. The operation of the apparatus was successfully tested by processing a large set of measurement results obtained from a composite material called "EXTREN". Our experiment results confirmed the correctness of both the EME and AE measurement method and measuring apparatus design. Our measurement results make it possible to track the behaviour of cracks, localize them and evaluate some of their basic parameters.

The formation of a crack is accompanied by the generation electromagnetic field, whose fundamental parameters were evaluated for a dipole model of the respective source. A differential equation was developed and solved to describe the transformation of the field parameters into an electric signal, provided capacitive and inductive sensors are used. In the next stage, an analysis of spurious external electromagnetic and acoustic fields was carried out and measures to suppress their effects were designed. The issue of amplifying extremely low electromagnetic signals generated during the crack formation was dealt with, too. The mentioned analyses resulted in the design of a method to detect and evaluate electromagnetic emission (EME) signals and acoustic emission (AE) signals, which accompany mechanical stressing of materials and structures. Based on the results of such analyses, an automated double-channel measuring apparatus for both signal data acquisition, saving and processing. The operation of the apparatus was successfully tested by processing a large set of measurement results obtained from a composite material called "EXTREN". Our experiment results confirmed the correctness of both the EME and AE measurement method and measuring apparatus design. Our measurement results make it possible to track the behaviour of cracks, localize them and evaluate some of their basic parameters.

composite, crack, electromagnetic emission, acoustic emission, electic charge

KOKTAVÝ, P., KOKTAVÝ, B.

2005

1. 1. 2005

Brno University of Technology

Brno

80-214-3053-2

Defektoskopie 2005, Sborník příspěvků

97

105

9