Design And Analysis Of The Flexible Ejection Structure Of Lizardoids

Lizards ejecting their soft tongues towards prey for capture is a biological phenomenon characterized by high speed,accuracy and flexibility.This characteristic has great potential for application in bionic special equipment,military science and technology,aerospace and other fields.However,the existing ejection mechanical structure mainly adopts rigid structure,which has defects such as large mass,slow speed response and destructiveness.Based on this,a bionic flexible ejection structure is designed inspired by the tongue-ejection mechanism of lizards.The structure is composed of flexible rubber material,and its intrinsic model is determined by super-elastomer theory,tensile test and finite element simulation;the kinematic equations of the bionic flexible ejection structure are established,and the kinematic analysis is carried out;on this basis,the ejection process of the bionic flexible ejection structure is analyzed by using a high-precision finite element model,and the effects of initial displacement and initial rotation angle on the velocity response time,range,and motion trajectory.The main research works are as follows.(1)A new flexible ejection structure imitating lizard animals was designed based on the inspiration of tongue ejection mechanism of lizard animals.Firstly,the component materials of this new type of flexible ejection structure were selected,and the new flexible ejection structure was determined to be composed of flexible hyperelastic rubber material based on the motion characteristics of large flexibility and fast velocity response.Secondly,because the Yeoh model simulates large deformation and tensile deformation with high accuracy and meets the deformation characteristics of large deformation and tensile deformation of the new flexible ejection structure,and the Yeoh model can be fitted by uniaxial tensile test data with few unknown parameters and has the highest solution efficiency;therefore,the Yeoh model is selected as the hyperelastic intrinsic model of the rubber material.Finally,the Yeoh intrinsic model parameters were determined as C₁₀=0.35?C₂₀=0.25 based on the fitting of tensile test data.(2)The motion model of the new flexible ejection structure is established by using the Lagrange method with the assumption of rigid body motion of the ejecta,and the motion characteristics of the new ejection structure are analyzed.Based on the assumption of rigid body motion of the projectile,the ejection process is divided into three stages:energy storage ejection,unconstrained motion and limiting motion,and a kinematic model of the flexible ejection structure of the mimic lizard animal is established for each stage of ejection motion,and the kinematic analysis is carried out to elucidate the fast ejection mechanism of the mimic flexible ejection structure;based on the physiological structure and ejection mechanism of the lizard animal,a model is designed to satisfy the velocity response.A new flexible ejection structure with fast,flexible and accurate kinematic characteristics was designed based on the physiological structure and ejection mechanism of the lizard,and the kinematic characteristics of the new ejection structure were analyzed by combining with finite element simulation.(3)A high-precision finite element model is further established to analyze the ejection characteristics of the new flexible ejection structure,and the influence of initial displacement on the ejection characteristics such as velocity response time,range and trajectory is studied in depth.Firstly,the accurate ejection model was established in the finite element simulation software using Standard&Explicit model and the nonlinear dynamics explicit finite element analysis was performed.According to the finite element analysis results,the ejection of the bionic ejection structure was completed within 10ms under the initial displacement of 9cm,the ejection velocity of the ejected object reached 80m/s,the eccentric distance of the ejected object was less than 0.5 mm,and the deformation and expansion ratio of the ejection structure is greater than 10,which verifies the characteristics of fast speed response and accuracy of the bionic ejection structure.Secondly,the parametric analysis of the new flexible ejection structure was carried out based on finite element analysis,and the effects of initial displacement on the ejection characteristics such as velocity response time,range and trajectory were studied in depth,and the variation curves of each ejection characteristic parameter with respect to time at different initial displacements were obtained,and the ejection laws of the lizard-like animal flexible ejection structure under different initial conditions were obtained through data fitting.