Novel lattice structures based on continuous fibers: Fabrication and mechanical properties

Composite sandwich structures containing high-performance core materials based on composite lattice structures have been manufactured using a lost-mold technique. The structures were prepared by drilling holes at specific locations through a dissolvable mold block. Long carbon fiber strands were then inserted into each of the holes, ensuring that one continuous tow extended through all of the elements within a given core structure. Well-defined lattice structures based on what are termed BCC, BCCz, FCC and F₂BCC, Pyramid and Octet designs were produced. Following infusion with epoxy resin, using the VARTM manufacturing procedure, individual specimens were removed from the blocks in preparation for subsequent compression testing. The specific compression strengths were found superior to those of more traditional core materials. A number of failure mechanisms were also highlighted, including strut buckling, fracture at the strut-skin joints and debonding of reinforcing members at the central nodes. Finally, it is believed that the properties of these lattices can be further increased using higher fiber volume fractions.