Compression and shear behavior of epoxy SA 80 bulk adhesive over wide ranges of strain rate

This paper deals with the experimental characterization of a bulk adhesive fracture in the quasi-static range using a conventional machine and at high strain rates using the Hopkinson bar technique. For very high strain rates, the direct impact Hopkinson bar technique is used. The studied adhesive is a toughened epoxy which can be used for impact resistance in bonded assemblies. It is worth studying the adhesive sensitivity to strain rate as a bulk material in order to distinguish between its response within a structure when used to bond substrates and its response as pure material. Experiments were carried out under compression and shear loadings. A special grip was conceived to mount the specimen for shear tests. In both loading types, this adhesive was found to be highly strain-rate-sensitive. The adhesive strength increases with strain rate until reaching a maximum value then it drops for very high strain rates. Although this behavior is uncommon, it has been reported already in three previous works.