Experimental Validation of the Energy Balance Equation in the Presence of Acoustic Emission

This study attempts to experimentally validate the energy balance equation during a quasi-static loading of polymer composites with explicit consideration of the energy dissipated through acoustic emission (AE). The experimental protocol estimates the various terms of the energy balance equation, namely the external work done EW, the elastic stored energy Ee, the dissipated heat energy EH, and the dissipated acoustic emission energy EAE using in-situ measurements. The elastic stored energy Ee is derived from strain gage data, the dissipated heat energy EH is estimated from the temperature field obtained from quantitative infrared thermography (IT) and surface mounted thermocouples, and the acoustic emission energy EAE is approximated using two surface mounted piezoelectric transducers. The total input energy Ew, i.e. the external work done by the loading system is calculated from the cross-head displacement. The energy balance equation, ignoring inertial forces, is written as EW − Ee − EH − EAE = Constant. The energy approach presented herein may be used to quantify the level of material degradation as well as remaining useful life in primary load carrying structures.