Nonlinear Flexural Behavior and Moment Curvature Response of Epoxy Resin Using Digital Image Correlation Technique

Abstract

The effect of local strain and stress distribution in the polymeric material under out of plane loading is of interest in many applications. Flexural testing of the epoxy resins is necessary to evaluate their mechanical behavior. In this paper, the flexural response of epoxy resin Epon E 863 and hardener EPI-CURE 3290 has been investigated in three point bending (3PB) at different strain rates. Beam specimens with rectangular cross sections, different lengths and span to depth ratios were tested at their mid point. Samples had either a quarter deep notch or a groove at their mid points. Strain fields within the beam structure were determined using digital image correlation technique. Load deflection curves at different load speeds were obtained. Limit of proportionality (LOP), modulus of rupture (MOR), initial slope of the load-deflection curve, and slope of load deflection curve after the LOP point were extracted. The nonlinear moment curvature behavior has been obtained. The results show that a digital image correlation can accurately categorize the material response of an epoxy resin for flexural loading. Results clearly display the strain rate effects on the material response.