Foam core sandwich structures made of two stiff and strong composite face sheets separated by a lightweight closed cell foam core, such as PMI foams, have a high potential to be integrated in a primary aircraft structure. Using resin infusion processes for the manufacturing of sandwich panels could reduce the production costs compared to honeycomb sandwich manufacturing. Moreover, sandwich structures exhibit high specific stiffness and strength compared to traditional with stringer stiffened composite shells, which could reduce the part count and makes the production more efficient. In addition closed cell foam cores overcome the issue of moisture take up and the resulted material degradation. All these benefits make this core material interesting for integration in primary aircraft structures. However foam core sandwich are prone to external localised loads, like low velocity impact in case of tool drop or foreign object impact, which could lead to serious structure damages like face sheet rupture or shear cracks that lead to the degradation of the load bearing capacity of the structure.
In order to overcome the issue of crack propagation owing to impact loading and to improve the fracture toughness of foam core sandwich, dry fibre bundles are inserted in the foam material under a specific inclination angel and pattern. The pins improve the stiffness and the strength of the foam core, stop the initiated cracks and maintain the integrity of the structure.
In this work, the impact behaviour of pin-reinforced foam core sandwich panels was simulated. The model was developed in ABAQUS/explicit code. With the aim to increase the accuracy of the simulation results, the building block approach and the multi-scale modelling technique were used. The face sheet and foam material models were validated separately. The pin-reinforced foam core was modelled with 8-nodes brick elements with homogenized material properties. The impact model was then validated by comparing the load-displacement curves and the failure modes from the simulation with that obtained from experimental investigations. It was concluded that developed model predicts the impact behaviour and failure modes accurately.