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

Abstract

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 E_W, the elastic stored energy E_ε, the dissipated heat energy E_H, and the dissipated acoustic emission energy E_AE using in-situ measurements. The elastic stored energy E_ε is derived from strain gage data, the dissipated heat energy E_H is estimated from the temperature field obtained from quantitative infrared thermography (IT) and surface mounted thermocouples, and the acoustic emission energy E_AE is approximated using two surface mounted piezoelectric transducers. The total input energy E_w, 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 E _W − E _ε − E _H − E _AE = 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.