Research On The Preparation And Basic Mechanical Properties Of Fiber Reinforced Composite Beetle Elytron Plate

Honeycomb sandwich plates have been widely used in aerospace,transportation,construction and other fields due to their advantages of light-weight,high-strength and well designable.Beetle forewing(or elytra)is also a kind of typical sandwich structure,which has the characteristics of light-weight,high-strength and high degree of optimization.Domestic and foreign scholars have carried out a lot of research on the structures of beetle forewing and proposed many biomimetic models.Our research group proposed a "trabecular-honeycomb" structure based on the 3D structures of the beetle forewing,proved the shared mechanism of the trabecular structure in beetle forewings,and verified that beetle elytron plate(BEP for abbreviation,a type of biological sandwich plate inspired by beetle elytra)with "hollow trabecularhoneycomb" core structure possesses prominent mechanical properties.However,how to prepare BEP with "hollow trabecular-honeycomb" core structure using fiber reinforced polymer has become a problem.At the same time,a biomimetic model with horizontal tubes in the core structure(hereinafter referred to as "horizontal tube model")based on the forewing of Cybister has been reported,and its compressive strength is 4.8 times that of honeycomb plate.So,it is necessary to find out the advantages and disadvantages of horizontal tube model and BEP and their intrinsic influence mechanism before carrying out further research on BEP.Therefore,the compressive performances of beetle elytron plate and horizontal tube model are analyzed by compression test and finite element simulation,and the biomimetic model of beetle forewing is determined for further study.Then,the preparation process of using chopped basalt fiber reinforced epoxy resin to prepare BEP is developed,BEP and honeycomb plate with equal core wall thickness are prepared.The mechanical properties of BEP using fiber reinforced polymer are investigated by flatwise compression.Also,the effect of material properties on the mechanical properties of BEP and their intrinsic influence mechanism are analyzed.(1)To compare the compressive performances of beetle elytron plate and horizontal tube model,a flatwise comparison experiment with a horizontal model with trabeculae,a pure-trabecular beetle elytron plate and a honeycomb plate,and the finite element flatwise simulation analysis of a horizontal tube model without trabeculae,an end-trabecular beetle elytron plate and a honeycomb plate are carried out.The results confirm that the beetle elytron plates with the structural characteristics of beetle forewing have better mechanical properties,and the artificially added horizontal tubes in the horizontal tube model will reduce the bearing capacity of the hollow trabeculae and cause material waste,resulting in the strength/mass ratio of horizontal tube is not even as good as that of honeycomb plate.According to this,it not only confirms the correctness of defining the horizontal tube model as a bionic "pseudo-proposition" according to the principle of structural bionics mentioned above,but also provides experimental and theoretical basis for the structural bionics’ principle and the conclusions in(1)above.This chapter strengthens and perfects the bionic system of the beetle forewing,and plays a positive role in preventing the occurrence of bionic "pseudo-propositions".(2)Based on the characteristics of BEP and fiber reinforced polymer,the preparation process of using chopped basalt fiber reinforced epoxy resin to prepare BEP is developed.The BEP and the honeycomb plate with equal core wall thickness are prepared.their compressive mechanical properties,damage morphology of the core structure and intrinsic influence mechanisms are investigated through flatwise compression experiment.The results show that the energy absorption capacity and specific strength of the BEP are increased by about 75.8% and 18.3% compared with those of the honeycomb plate,respectively.but the difference in compressive strength between them is small.For the former,in the initial stage of the failure of the hollow trabecula,its upper and lower parts can still form a relatively stable vertical bearing structure due to the existence of the hollow trabecular-honeycomb structure in BEP,so,the bearing capacity of the BEP decreases slowly after reaching the maximum bearing capacity and a better energy absorption capacity is obtained.For the latter,Since the overall damage of the two sandwich plates is caused by the material damage caused by the shear stress of the core wall,and 45° fracture cross sections are formed,the difference in compressive strength between them is small.When the core structure of BEP does not undergo buckling deformation,the damage of the core structure is determined by the strength of the material.Based on this,it is proved that if BEP which is a bionic real proposition is to fully exert its superiority,it is necessary to pay full attention to dimensions of the core structure and the properties of the preparation materials.Otherwise,the superiority of the biomimetic model may not be exerted.It laid a theoretical foundation for the correct implementation of structural bionics research.This will lay the theoretical foundation for the correct implementation of structural bionics research.