Analysis of the compression behaviour of different composite lattice designs

Four all-composite lattice designs were produced using a lost-mould procedure that involved inserting carbon fibre tows through holes in a core. Following resin infusion and curing, samples were heated to melt the core, leaving well-defined lattice structures based on what are termed BCC, BCCz, FCC and F₂BCC designs. Analytical and numerical models for predicting the mechanical properties of the four designs are presented and these results are compared with the experimental data from the quasi-static compression tests. Compression tests on the four lattice structures indicated that the F₂BCC lattice offered the highest compression strength, although when normalized by relative density, the BCCz lattice structure out-performed other structures. Similarly, the specific compression strengths were found to be 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 fibre volume fractions.