Design of 3D printed cores to improve radial compression behaviour of pultruded composite tubes

Abstract

E-glass/vinylester composite crash structures manufactured by ultraviolet (UV) pultrusion process have shown high values of especific energy absorption (SEA). However, comparing the radial compression behaviour of the tubular structures with the axial crushing behaviour, it has been noticed that the stiffness and the strength of the structures to radial compression is too low. In order to improve the radial compression behaviour of the structures manufactured by UV pultrusion, different cores have been designed and manufactured by 3D printing using FDM (Fused Deposition Modeling) technology. On the one hand, an hexagonal core consit on a thin external skin made with ABS and filled with 3D printing support material has been analyzed. Otherwise, an hexagonal core designed following the honeycomb concept has been printed and tested. The composite structures with the cores have been tested in radial compression in quasi-static conditions and they have shown higher stiffness and strengh due to the 3D printed internal cores. The composite structure with the hexagonal ABS skin core and support material has improved the stiffness of the composite tubular structure 9 times while the strength has increased 5 times. In the case of the honecomb ABS core, the stiffness of the structure has increased from 1.15 kN/mm to 22 kN/mm (19 times more). Meanwhile, the strenght values using the ABS honeycomb core has been 17 times higher than the empty composite structure.