Study of Equivalent Mechanical Properties and Energy Absorption of Composite Honeycomb Structures

In this study, an analytical model based on classical laminate theory (CLT) is proposed to predict the equivalent mechanical characteristics of three-dimensional (3D) printed fiber-reinforced polylactic acid (PLA) honeycomb structures. Higher rigidity and strength in comparison with the structures made of pure isotropic materials are presented by employing fiber-reinforced PLA. Tensile tests and finite elements studies are conducted to verify the developed analytical relationships. A good agreement is found between the experimental, numerical, and analytical results. Consequently, the mechanical characteristics of the aforementioned structures can be properly predicted using the presented analytical relationships. Moreover, the study examines the impact of using commingled yarn instead of single yarn as a fiberglass strut and finds higher ultimate tensile strength. Compression tests are also conducted to examine the energy absorption capacity of polyurethane foam-filled and hollow honeycomb structures. Finally, a parametric study is conducted to evaluate the effects of geometry on the elastic modulus and Poisson's ratio of the honeycomb structures.