An investigation of the strength and stiffness of weight-saving sandwich beams with CFRP face sheets and seven 3D printed cores

Abstract

Although sandwich panels are widely used in the industry, the limitations in the cores’ structure designs and materials restrain their use in stiffness- or strength-critical applications without increasing the sandwich beams’ dimensions. The use of additive manufacturing over conventional fabrication methods enabled us to tune the cores’ design according to the stiffness and strength requirements without increasing the beams’ overall dimensions. Seven core structures were 3D printed of Nylon PA12 using powder bed fusion and were tested for their strength and stiffness using three-point bending test. The novel 3D printed core structures were combined, for the first time in the literature, with thin CFRP face sheets. The small Re-entrant and Gyroid structures achieved the highest strength and stiffness values respectively, while the 3D printed conventional honeycomb structures performed the poorest among all other core structures. The stiffness and strength values were normalised using the samples weights and the gyroid structure recorded the highest specific stiffness and strength, making it ideal for supporting weight-critical applications such as motorsport and aerospace.