16. Processing and Opto-mechanical Characterization of Transparent Glass-Filled Epoxy Particulate Composites

A transparent glass-filled epoxy composite was developed by matching the refractive index of the filler and the matrix. This material was processed at varying volume fractions (V _f) from 0 to 15 % of filler with transparency being maintained at each V _f. Initial investigation included quasi-static three-point bending to determine the critical SIF (K _Icr) values. Improvement over the neat epoxy was seen in each case with a maximum improvement of approximately 30 %. Furthermore, this material was observed to exhibit birefringent properties, thus making mechanical characterization through photoelastic methods feasible. The samples were loaded using a symmetric four-point bending set up and isochromatics were observed using a dark-field polariscope. The stress intensity factors for each sample were evaluated at various loads and compared to those determined analytically. Experimental measurements closely matched analytically determined ones, thus validating the use of this method. This work-in-progress includes investigating the fracture behavior of these composites under low and high strain rate conditions.