Impact damage response of natural stitched single lap-joint in composite structures

• To study the impact resistance of single lap-joints in composite structures.
• To improve the impact resistance of stitched single lap joints using natural Flax yarn.
• To investigate the effect of stitching on the damage process of composite materials.
• To develop FE techniques to model the impact process of composite structures using LSDYNA.

In this paper the damage behaviour of natural stitched composite single lap-joints are investigated under low velocity impact loading conditions. For this study, the laminated hybrid composite beams were pinned using Flax yarns before curing process. The Charpy impact test was chosen to study the energy absorbing capability of single lap composite joints. Composite beams were fabricated from combination of glass/epoxy and carbon/epoxy composites. It was shown that composite beams which are stitched through the thickness are able to absorb more energy in comparison with adhesive bonded composite joints in the hybrid composite beams. The Charpy impact test of stitched composite single lap joint was also simulated by finite element analysis using software LS-DYNA and the results verified with relevant experimental data.