Mechanical Performance Of Rapid Prototyping Plastic Honeycomb Sandwich Structure

Composite sandwich structures are attractive for various applications,such as aerospace,transport,civil,military applications etc.And they have many advantages,such as lightweight and high stiffness/strength-to-weight ratio properties.In this paper,we design and manufacture different plastic cores with 3D printing technology,and the material of the core is PLA.The mechanical performance of the sandwich structures with 3D printed cores were analyzed.In order to determine the mechanical properties of the core material,solid cylindrical and dumbbell-like specimens were printed and tested.The results indicate,the tensile strength of the Nature WorksTM PLA Polymer 6202D is very similar to our samples.The open-cell cores of the sandwich structures were designed using 3D designing software.Various grids are well-designed such as Bi-grid,Tri-grid,Quadri-grid and Kagome-grid.The effects of different open-core structures on the mechanical properties of the sandwich structure were investigated.In this paper,the bending performance of Nomex honeycomb sandwich structure was also tested,the loading capacity was lower than that of printed core sandwich structures.Combining the results of finite element analysis and three-point bending test,the failure modes of Bi-grid sandwich structure was the interfacial de-bonding between the core and face sheet.While the failure modes of the Tri-grid,Quadri-grid and Kagome-grid were core shear.The mechanical performance of Quadri-grid sandwich structure was the best.Then,the Bi-grid,Tri-grid,Quadri-grid and Kagome-grid closed-cell cores were designed and fabricated using 3D printing technology.Mechanical performances of the sandwich structures were characterized using finite element analysis and three-point bending test.Results indicate,the failure mechanism of closed-cell cores were very similar to open-cell cores,and the toughness of the Bi-grid honeycomb core has increased.With the weight increase,the specific strength of the closed-cell core has been significantly improved.To further explore the energy absorption of hierarchical structures,mechanical performances of the Regular Honeycomb,1st Order Hierarchy and 2nd Order Hierarchy were characterized using finite element analysis,three-point bending test,edgewise compression and compression after impact properties.The results indicate,hierarchical honeycomb structure was not suitable for bending,shear requirements of the larger environment,but the energy absorption and compression performance has greatly improved.