Research On Structure Design And Properties Of Honeycomb Based On 3D-printed Fiber Reinforced Composites

Under the background of "Made in China 2025",3D printing is one of the research hotspots at present.Especially,fused deposition modeling(FDM)shows great advantages in3 D printing of fiber reinforced composite parts.Negative Poisson's ratio honeycomb has many applications in automobile and other fields because of its excellent energy absorption,shock resistance and earthquake resistance capacities.However,the deformation of negative Poisson's honeycombs are usually irrerecoverability and can not be used repeatedly.Concerning on this problem,the aim of current work focus on the compression performance of negative Poisson's ratio honeycomb.Based on the performance,the structural design and improvement are proposed to achieve programmable rebound-selflocking compression behavior.The specific research contents are as follows:(1)The mechanical properties of e-PA,e-PA/CF,PEEK and PEEK/CF printing filaments were studied by tensile test.The negative Poisson's ratio honeycomb forming was established and manufactured by FDM technology.The influences of different material characteristics on the deformation mode,mechanical properties,energy absorption and resilience of negative Poisson's ratio honeycomb were studied through in-plane quasi-static compression tests.The experimental values were compared with the theoretical values.The results showed that the e PA/CF possessed relative strong tensile strength and Young's modulus.The deformation mode of negative Poisson's honeycomb was "layer upon layer collapse",and the corresponding platform stage presented fluctuation change.The maximum compression strength,compression modulus and specific energy absorption were e-PA/CF honeycomb,and they showed high resilience,and thus e-PA/CF was selected as the research object in the following chapters.(2)Based on the study of negative Poisson's ratio honeycomb structure,an improved negative stiffness honeycomb structure was proposed and manufactured by FDM.The deformation mode,mechanical properties,energy absorption and springback of these two kinds of honeycombs were compared by compression tests.The results showed that the negative Poisson's ratio honeycomb showed the instability and unrecoverability of the vertical beam,while the improved negative stiffness honeycomb exhibited the buckling deformation of the inclined beam,and the deformation was recoverable after releasing the compression force.At the same compressive displacement,the energy absorption capacity of negative Poisson's honeycomb was greater than that of negative stiffness honeycomb,but the resilience was less than that of negative stiffness honeycomb.(3)Using e-PA/CF as printing filaments,the effects of structural parameters of negative stiffness honeycomb(including included angle,beam wall thickness,vertical beam wall thickness and inclined beam wall thickness)on compressive performances(including deformation mode,mechanical properties,energy absorption and resilience)were studied.The results showed that the deformation mode of the negative stiffness honeycomb was mainly manifested as the "floor by floor buckling" deformation of the inclined beam or the buckling deformation of the local diagonal diagonal beam.The thickness of the inclined beam was relatively small to realize the self-locking of the inclined beam easily,while the vertical beam almost does not deform.The beam can enhance the stiffness of the honeycomb and limit the transverse deformation.The energy absorption of the honeycomb increases non-linearly with the increase of the included Angle and wall thickness,and the responses of the included angle and wall thickness to the energy absorption of the honeycomb were different.By adjusting the structural parameters,the change of honeycomb from springback to self-locking can be realized.In this paper,the in-plane quasi-static compression performance of negative Poisson's ratio honeycomb prepared by different FDM materials is investigated,which provides a reference for energy absorption and collision avoidance structure.By designing the negative stiffness honeycomb structure,the rebound-selflocking compressive behavior is programmable realized,suggesting great potentials in energy absorption devices,buffer devices,vibration isolation and noise reduction.