Design Of A Fully-Compliant Hinge With Large Rotation Angel And Small Axis Drift Of XIDIAN UNIVERSITY

With the continuous development of miniaturization,precision,and high speed in the field of machine manufacturing,traditional rigid mechanisms and rigid hinges cannot satisfy the needs due to friction,wear,and lubrication problems associated with assembly and structure.The emergence of flexible mechanisms and flexible hinges solves these problems better.Compliant mechanism is a kind of mechanism that utilizes its partial or its entire elasticmember to store energy and release energy and in this process it obtains the mechanical force,displacement or motion according to the design requirements.Because this type of mechanism is easy to be formed,no need to assembleand has excellenct features,such as no friction,no lag,no abrasion and lubrication,easy maintenance,compact structure,non-moving clearance,small volume size,and high resolution,the flexure hinges are widely used in many fields,such as precision machines,instruments,micron and nanometer technology,despite their rotational angle is limited.Firstly,this thesis introduces the concept of compliant mechanisms and several major application areas of compliant mechanisms and summarizes the researches on the compliant mechanisms of the domestic and international in recent years.And secondly this thesis illustrates four flexible hinges.According to the structural features and rotational degree of freedom of the hinges,they are divided into single-axis—cross-spring flexible hinge,biaxial—universal flexible hinge,and three-axis—two kinds of three degree of freedom flexible hinges.First,the finite element analysis software is used to simulate the rotational stiffness,axis drift and rotation range of the cross-spring flexible hinge.The influence of the thickness of the spring on the rotational stiffness is established by the quadratic fitting equation.This thesis compares the rotational stiffness from FEA with the rotational stiffness,which is tested by setting up the experimental platform.Second,the stiffness of the universal flexible hinge is analyzed and the force diagram is used to establish the equation,and the mathematical formula of the axis drift is deduced.Finally the load-angular displacement characteristic curve and the overall deformation diagram are obtained.Two kinds of three-axis hinges based on cross-spring flexible hinge are simulated and the advantages and disadvantages of the two kinds of hinges are compared.