Designs of lattice truss core sandwich structures with improved compressive strength and stiffness

Abstract

Lattice truss core sandwich composite (LTCSC) panels can exhibit high compressive performance until failure is caused by compressive fracture of the composite strut. Early failure of the core-facesheet and central nodes, as well as fiber misalignment, can hinder the full potential of an LTCSC. This study aimed at improving the compressive stiffness and strength of LTCSC panels through minimizing the fiber misalignment and fabrication issues, while strengthening the central and core-facesheet nodes. The lost-molding technique was used to fabricate LTCSC panels, which were then subjected to quasi-static flatwise compression testing. Relative positioning of neighboring composite struts, modification of the carbon fiber path, and strengthening of the core-facesheet node significantly improved the compressive performance of the panels. Based on the findings, compressive strength and stiffness of LTCSC panels can be improved about 100% and 300%, respectively, with minimal increase in weight. Fabricated LTCSC panels were found to demonstrate competitive specific compressive properties in comparison with conventional core materials.

Improved compressive performance of lattice truss core sandwich composites with modified Kagome topologies: An experimental and numerical study

“…This flaw is caused by the partially intersected composite struts, i.e., neighboring struts having a common volume near the central zone. Based on the results of our previous study, 20 the cross-sectional surface area of composite struts was reduced by about 30% at the central node, resulting higher carbon fiber volume fraction near the central node regions ( V f ≈11.3%) compared with the facesheet node regions ( V f ≈8.4%). The uneven surface of the facesheets due to the presence of carbon rovings between the plies may have a slight adverse effect on the compressive properties.…”

“…This method provides good reproducibility of the lattice truss cores with exactly the same geometric characteristics. 20 Based on our previous findings, 20 partially intersected channels were found to provide a fairly strong bond between neighboring struts and also provided sufficient room for carbon rovings. Figure 1(a) presents a schematic illustration of holes being created in the waxing blocks in accordance with the topology.…”