Optimal design of sandwich beams with lightweight cores in three-point bending

Being widely used in engineering, the optimization of sandwich beams to achieve greater stiffness-to-weight ratio is of great research interest. In this paper, the optimization process was carried to obtain minimum weight designs in three-point bending based on prescribed stiffness index. Results indicate that honeycomb-cored sandwich beams possess smaller minimum weight index in comparison with metal foam-cored beams. In addition, failure mechanisms of the optimized designs were also investigated to reveal that the sandwich-cored beams were more prone to face wrinkling than metal foam-cored beams. In the optimization process, five different core topologies and four different parent materials were investigated under a given load index. It was found for low prescribed load values where bending is dominant, unidirectional lattice composite sandwich beams bear loads more efficiently than steel cored beams. However, the primary mode of failure for high prescribed load index is core shear, thus implying no significant advantage in lattice composite sandwich beams over other materials. Comparing the different materials, that laminate lattice composite sandwich beams possess the best bending performance for varying levels of prescribed load index, making it suitable for applications in the aerospace field.