The impact response of a Nomex® honeycomb core/E-glass/epoxy composite sandwich structure to increasing velocities: Experimental and numerical analysis

Abstract

The impact response of an E-glass fiber reinforced epoxy/Nomex® honeycomb core sandwich was investigated both experimentally and numerically at increasing velocities through concentrated quasi-static indentation force (CQIF), low velocity impact (LVI) and high velocity impact (HVI) tests. The composite face sheets and core were modelled using MAT_162 and MAT_026 homogenized material model in LS-DYNA, respectively. The experimental and numerical LVI test forces corresponding to core crushing and face sheet penetration were shown to be higher than those of the CQIF tests and increased as the impactor velocity increased. The increase of the impact forces at increasing velocities was largely ascribed to the inertia and the strain rate sensitive fracture strength of the composite sheets. The core shearing was detected in the CQIF and LVI tests both experimentally and numerically. It was also detected in the HVI tests at the velocities less than 20 m s−1. The deformation in the HVI tests at and above ∼ 29.4 m s−1 was highly localized in the impact area with no core shearing and a large delamination damage area at the front face sheet. The force enhancement due to the micro-inertia of the core deformation was shown to be not significant at the studied velocities.