Study On Static And Dynamic Mechanical Properties Of Re-entrant Negative Poisson's Ratio Honeycomb

Negative Poisson's honeycomb material which has special mechanical properties: higher relative stiffness,strength and efficient energy absorption capacity,has unique advantages in shear resistance,buckling resistance,hardness improvement and fatigue resistance.In automobiles,aircraft,medical equipment and military equipment,it has a great application prospect.It is worth noting that the negative Poisson's ratio honeycomb material is often defective and non-uniform,and susceptible to multi-axial action in actual working conditions.Therefore,it is very important to study the multi-axial and non-uniform mechanical properties of negative Poisson's ratio honeycomb materials.Based on the re-entrant negative Poisson's ratio honeycomb structure,the re-entrant negative Poisson's ratio honeycomb structure with different irregularities is establi shed by coordinate disturbance.By the finite element analysis software ABAQUS,the quasi-static compression,in-plane dynamic mechanical behavior and in-plane dynamic mechanical behavior of density gradient honeycomb about the regular re-entrant honeycomb and the re-entrant honeycomb with irregular degree were simulated and analyzed by finite element method.The specific research contents are as follows:(1)First,uniaxial quasi-static compression was carried out on the regular model in both X and Y directions to obtain the elastic modulus and Poisson's ratio of the studied structu re.The results of finite element simulation analysis and theoretical calculation were verified to verify the validity and correctness of the model established in this paper and the data processing method.After the disturbance,the model was subjected to uniaxial quasi-static compression in the same two directions,and the effects of relative density,irregularity and anisotropy on the uniaxial quasi-static compression performance of the structure were analyzed.Meanwhile,the effects of different degrees of disturbance on the mechanical properties of the structure,such as elastic modulus and Poisson's ratio,were also studied.(2)For regular re-entrant honeycomb and disturbed honeycomb with different regularity,under different impact velocities,uniaxial impact in X and Y direction in plane and equal biaxial impact under XY composite loading were simulated and analyzed in terms of deformation mode,dynamic response curve and energy absorption capacity of the structure.The deformation trend of the structure at different strain times is analyzed,and the platform stresses in X and Y directions are compared under uniaxial and biaxial impact.The influence of the introduction of irregularity on the in-plane dynamic impact performance of the re-entrant negative Poisson's ratio honeycomb structure is also analyzed.(3)Two density gradient structures of re-entrant negative Poisson's ratio honeycomb structures with different irregularities were studied.Under uniaxial impact,the top-down positive gradient honeycomb structure was studied,while under biaxial impact,the "back" type positive and negative density gradient honeycomb structure was studied from outside to inside and from inside to outside.Under different impact velocities,their in-plane dynamic mechanical properties were studied in terms of deformation mode,dynamic response and energy absorption.The effect of the introduction of irregularity on the mechanical properties of density gradient honeycomb structure is also analyzed.