Determination of Crack Surface Orientation in Carbon Fibre Reinforced Polymers by Measuring Electromagnetic Emission

Abstract

Electromagnetic emission (EME) generated by fracture of carbon fibre reinforced polymers (CFRP) is studied. The fracture is induced to cross-ply CFRP by mechanical loading in a three-point bending configuration. An EME acquisition setup operating on the principle of capacitive coupling is used to measure the low frequency (kHz-MHz range) electric field whose generation is attributed to the charge redistribution accompanying the fracture processes. Multiple, differently oriented EME sensors, for the simultaneous EME measurement with different source-sensor orientations, were applied to account for the directionality of the EME sources and their generated electric fields. A method to deduce the crack orientation based on the emitted EME field's directionality is proposed. A comparison between the angles of the EME sources obtained by this method and the actual crack surface orientations as determined by computed tomography is made.

Influence of alkali-activated materials placement during curing on their dynamic parameters

“…The acoustic bond may be formed by a thin layer of a suitable binder. [17] We used plasticine as a binding agent for our measurements. The time of passage through the layer of acoustic bonding material and the through the probe is called dead time.…”

A review on deformation-induced electromagnetic radiation detection: history and current status of the technique

“…Photoemissions (in some cases electron emissions) were detected before, during and after fracture. It was observed that photoemissions are prevalent for the weak bonds which fail due to adhesive failure, whereas strong bonds have cohesive failure with less photon emissions [198,199]. Dickinson and co-workers have found that during fracture adhesive bonds and peeling pressure-sensitive adhesives involve large amounts of charge separation and the emission of charged particles, excited neutrals, light and radio waves.…”

“…To understand the crack surface orientation using electromagnetic emissions different source to sensor orientations and distances of antenna have been used. Consequently, a method has been developed in which crack orientation can be known based on the directionality of electromagnetic fields [199]. Langford et al have investigated the photon emissions from fracture of epoxy and have proposed a method to probe fractal surface of the epoxy through the accompanying photoemissions.…”

“…Further increase in the deformation builds up the stress in the remaining fibre lengths leading to fracture and the process is again repeated [198]. Gade et al have also considered the formation of dipoles on the surface of crack as the possible source of electromagnetic emissions and have modelled the electromagnetic source as electrical dipole like sources [199].…”

Диагностика Разрушения Армированного Бетона В Условиях Изгиба По Параметрам Электрического Отклика На Ударное Воздействие

“…В настоящее время предложено большое количество методов, которые позволяют определять повреждения в бетоне. Среди них метод акустической эмиссии [5,6], электрической и электромагнитной эмиссии [7][8][9], импакт-эхо методы [10,11], ультразвуковые и лазерные методы [12][13][14][15], импедансные методы [16,17] и др. Наряду с этими методами разрабатывается метод оценки повреждения бетона, основанный на характеристиках электрического отклика, возникающего в бетоне в результате импульсного механического воздействия [18][19][20][21].…”