Test methodA modified short beam shear specimen for characterization of interfacial strength in nanocomposites

Analysis and design of a modified short beam shear (MSBS) specimen for interfacial strength characterization of nanocomposites was investigated using finite element analysis and testing. The MSBS specimen is a sandwich beam which consists of two relatively thick aluminum beams bonded to a thin core made of the nanocomposite material under test. To examine the specimen experimentally, polymer nanocomposites consisting of a thermosetting vinylester resin reinforced with multi-walled carbon nanotubes (MWCNTs), with and without chemical functionalization, were tested using the MSBS specimen. The failure mode observed for these nanocomposites is a result of a combination of shear and normal stresses, mainly due to the high brittleness of the vinylester matrix. Although the stress state existing in the nanocomposite is not pure shear, the mechanical strength measured by the MSBS specimen is sensitive to the chemical functionalization of MWCNTs.