Dynamic damage initiation of composite beams subjected to axial impact

The dynamic damage behavior of carbon-epoxy laminated beams, having initial geometric imperfections, subject to an axial impulse was investigated numerically and experimentally. The study focused on investigating the damage initiation and damage mechanism in the beams impacted axially by a moving mass. The dynamic equilibrium equations were developed based on the Timoshenko beam assumption with the consideration of beamʹs transverse inertia, transverse shear deformation and the cross sectionʹs rotational inertia effects. The Higher-Order Shear Deformation Theory was adopted to model the nonlinear distributed shear strain across the beam thickness. The von-Karman Strain–Displacement nonlinear relationship was used to model the deformation of the beam. Hashinʹs failure criteria was used to predict the damage of beams. The experiments were conducted using a horizontal linear bearing impact setup. Scanning Electron Microscopy results showed that delamination and matrix crack were the primary damage mechanisms in the beams. Effect of fiber angle, lay-up sequence and initial geometric imperfection on critical energy of damage initiation was also investigated.