A Tensile Split Hopkinson Bar for Testing Particulate Polymer Composites Under Elevated Rates of Loading

Abstract

A tensile split Hopkinson bar apparatus is developed for testing high strain rate behavior of glass-filled epoxy. The apparatus uses a specimen gripping configuration which does not require fastening and/or gluing and can be readily used for castable materials. Details of the experimental setup, design of grips and specimen, specimen preparation method, benchmark experiments, and tensile responses are reported. Also, the effects of filler volume fraction (0–30%) and particle size (11–42 μm) are examined under high rates of loading and the results are compared with the ones obtained from quasi-static loading conditions. The results indicate that the increase in the loading rate contributes to a stiffer and brittle material response. In the dynamic case lower ultimate stresses are seen with higher volume fractions of filler whereas in the corresponding quasi-static cases an opposite trend exists. However, the absorbed specific energy values show a decreasing trend in both situations. The results are also evaluated relative to the existing micromechanical models. The tensile response for different filler sizes at a constant volume fraction (10%) is also reported. Larger size filler particles cause a reduction in specimen failure stress and specific energy absorbed under elevated rates of loading. In the quasi-static case, however, the ultimate stress is minimally affected by the filler size.