Zero Poisson’s Ratio Structure And Geometric Nonlinear Analysis Of Fingertip Gyroscope Configuration

With the rapid development of modern information technology,variable polar distance capacitive sensors are widely used in various industries with their superior performance of high sensitivity and functional stability.The dielectric layer structure of the sensor is prone to horizontal strain under vertical loads when a variable polar distance capacitive sensor operates,resulting in certain strain losses and posing a threat to the accuracy of the sensor.Therefore,how to construct a dielectric layer structure with stable horizontal deformation and analyze the mechanical behavior of the structure during deformation is crucial for improving the comprehensive performance of variable pole distance capacitive sensors.Under vertical loads,zero Poisson’s ratio structures do not expand or contract horizontally during deformation.Based on the fingertip gyroscope of children’s toy,this thesis designs a porous metamaterial with zero Poisson’s ratio for fingertip gyroscope.Based on the basic assumption of linear elasticity,combining theoretical analysis,finite element simulation and experiment,the mechanical properties of the structure are analyzed by using energy method,the influence of geometric parameters of porous structure on the equivalent Poisson’s ratio and equivalent elastic modulus of the structure is explored,the influence of nonlinear factors on the performance of structural mechanics is studied,and the change law of structural mechanics characteristics is explored.The specific research content of this article is as follows:The strain loss of the dielectric layer structure in the vertical direction of the load threatens the measurement accuracy of the sensor.In order to solve the problem,this thesis designs a zero Poisson’s ratio porous metamaterial of the fingertip gyroscope.The deformation behavior of the structure was analyzed using the energy method,and the influence of geometric parameters on the equivalent Poisson’s ratio and equivalent elastic modulus of the structure was theoretically analyzed.It was found that there is a significant difference in the equivalent elastic modulus of the structure at the same size scale by adjusting the angle parameters of the structure.In order to investigate the influence of the number of rods and the outer convex angle on the equivalent mechanical performance of the structure,a new type of fingertip gyroscope structure was obtained by introducing rod and angle parameters based on the fingertip gyroscope structure.The equivalent Poisson’s ratio and equivalent elastic modulus were analyzed at both the theoretical and finite element levels.The numerical simulation results were highly consistent with the theoretical prediction results,confirming the scientific nature of the theoretical derivation.The prediction of actual deformation can be inaccurate when the nonlinear term in the theoretical formula of porous structures has been neglected.To solve the problem,this thesis proposes an improved variable step iteration method to study the nonlinear term in the theoretical formula of mechanical equivalent calculation models,which improves the nonlinear theoretical analysis of structures.The key to this method is to determine the displacement of the free end of the equivalent mechanical model,taking into account the nonlinear superposition of the rigid body motion of the member.On this basis,theoretical research on geometric nonlinearity was carried out for the new fingertip gyroscope structure,and analytical expressions for nonlinear equivalent Poisson’s ratio and equivalent elastic modulus were derived,accurately predicting the true deformation of the fingertip gyroscope structure.The necessity of considering nonlinear factors was concluded after co MParing the theoretical prediction results before and after considering nonlinear factors.The finite element simulation of a new fingertip gyroscope structure was conducted using ANSYS,and the simulation results revealed the necessity of considering nonlinear factors.In response to the influence of nonlinear factors on the equivalent Poisson’s ratio and equivalent elastic modulus of the structure during deformation,four sets of cell structures with different geometric parameters were prepared using 3D printing technology for quasi-static compression experiments.The equivalent Poisson’s ratio and equivalent elastic modulus of the structure during deformation were determined after experiments.The quasi-static compression experimental results are in good agreement with the nonlinear prediction results,and there is a significant difference between the experimental results and linear prediction results,revealing the necessity of considering nonlinear factors.Therefore,the true deformation of the structure can be grasped by considering the nonlinear factors of structural deformation,which helps to accurately control the vertical deformation of structural loads,promote the design of zero Poisson’s ratio dielectric layer structures,and improve the comprehensive performance of sensors.