Fabrication and mechanical properties of composite pyramidal truss core sandwich panels with novel reinforced frames

The novel composite pyramidal truss core sandwich panels with reinforced joints are manufactured by the water jet cut and interlocking assembly method. Here, the relative density of the carbon fiber composite pyramidal truss cores varies in the range 0.88-4.4%. The out-of-plane compression and shear performance of sandwich structures are investigated. Analytical estimates for sandwich panel strength are presented for possible competing failure modes. In general, the measured failure loads show good agreement with the analytical predictions. The measured quasi-static uniaxial compressive strength increases from 0.53 to 8.9MPa with increasing over the relative density range investigated here. The shear strength of lattice cores is improved by eliminating core-to-face sheet bond failures. The measured quasi-static shear strength varies between 0.78 and 1.75MPa. Compared with node non-reinforced composite pyramidal truss sandwich panels, under the relative density of 1.8%, the shear strength of node reinforced sandwich panels increases by 120%, and its shear modulus increases by 26.5%.