Hybrid lightweight composite pyramidal truss sandwich panels with high damping and stiffness efficiency

Hybrid composite pyramidal truss sandwich panels combined with multiple damping configurations are fabricated in this work. Modal and quasi-static compressive tests are carried out to investigate the damping and stiffness efficiency of the candidate structures. Experimental results show that such structures combined with damping materials would significantly improve the damping loss efficiency but decrease simultaneously the stiffness efficiency in varying degrees compared with the bare hybrid sandwich panels. In order to evaluate the compatible effect of total damping and stiffness efficiency of the present sandwich structures, a synthetic evaluation criterion is developed, which shows that bare sandwich panels filled with hard polyurethane foam (B-II-HPF) and soft polyurethane foam (B-II-SPF) can yield the best performance up to 2-4 times higher than the base hybrid sandwich panels. It is also shown that multiple patch damping treatments based on the finite element-modal strain energy (FE-MSE) approach are suitable and effective to further improve the total damping efficiency.