The compressive response of octet lattice structures with carbon fiber composite hollow struts

Abstract

Octet lattice structures were designed with carbon fiber reinforced polymer (CFRP) composite hollow cylindrical struts to improve the specific compressive strength and stiffness of these lightweight structures. A joint connector was designed and manufactured from balanced [0/90] CFRP laminates to assemble the designed octet lattice structures. The compressive modulus and strength of CFRP cylindrical tube-based octet lattice structures were measured under quasi-static compression. Two competing failure mechanisms were observed. The fiber fracture of CFRP hollow struts dominated the failure of lattice structures with a relative density (ρ-) of 2.17%. In contrast, lattice structures with lower relative densities (ρ-= 1.33% and 0.85%) failed by Euler buckling of the CFRP hollow struts. To gain further insight of the compressive behavior of the lattice structures, an analytical model and a series of finite element (FE) models were developed. The predictions showed good agreement with experimental observations of both the compressive properties and failure behaviors. The results demonstrate that CFRP tube-based octet lattice structures exhibited significantly higher relative strength and stiffness than CFRP laminated strut-based counterparts. These superior properties of CFRP tube-based octet lattice structure show a strong potential in high performance lightweight load-bearing application.