Effects of the loading direction on high strain rate behavior of woven graphite/epoxy composites

Effects of the loading direction on high strain rate behavior of cylindrical woven graphite/epoxy composites are presented. Compressive split Hopkinson pressure bar (SHPB) was used for high strain rate experiments. Cylindrical specimens were loaded diametrically and transversely at the impact energies of 67 J, 163 J, and 263 J. Micro Laser Raman spectroscopy and scanning electron microscopy (SEM) were used for surface characterization. It is observed that diametrically loaded specimens show permanent plastic deformation with high ductility resulting in a catastrophic failure while transversely loaded specimens exhibit viscoplastic deformation with some recoverable damage. As a result of this, Raman peak shifted to higher values for the diametrically loaded fibers whereas almost no change was observed in the Raman shift of transversely loaded fibers