The fabrication and mechanical properties of novel composite lattice structures

Abstract

A range of lattice structures, based on a carbon fiber reinforced epoxy composite, have for the first time been manufactured using a lost-mold technique. Here, core structures for potential use in sandwich panels were prepared by drilling holes in a well-defined pattern through either a high quality wax block or a machined salt slab. Continuous carbon fiber strands were then inserted through each of the holes in the perforated array, ensuring that one continuous tow extended through all of the elements within a given core structure. Two threading techniques were used to prepare the composite columns. Initial attention focuses on vertical truss cores and this is then extended to consider more complex structures.Following infusion, using the VARTM manufacturing procedure, individual specimens were removed from the resulting sandwich panels in preparation for subsequent mechanical testing.Compression showed that the strength of individual struts and the corresponding cores increases with strut diameter and fiber volume fraction. Smaller diameter struts failed in buckling, whereas the larger diameter columns failed in a crushing mode involving high levels of energy absorption. Finally, the properties of the various lattice structures considered here were predicted using finite element modeling techniques.