Fracture Related Electromagnetic Emission Measurement and Excess Noise Analysis of Reinforced Composites

Electrical properties of several types of reinforced composites were investigated. AC and DC resistivities were measured, and the frequency behavior along with parasitic components was put together in order to create equivalent electrical circuit. It was used for electrical noise measurement corrections. It turns out that samples produces high level Johnson-Nyquist noise and 1/f noise when current bias is applied. We have discovered that electrical contact metallization affects directly the 1/f noise and the bulk material is responsible for white-like Johnson-Nyquist noise. We managed to get information about the suitability of the various metals in view of noise generation and the silver conductive pint seems to be proper chose. Finally, the electromagnetic emission signal, which in turn depends on cracks, was measured and comparison with conventional acoustic emission was put forward.