Life Prediction And Influencing Parameter Analysis Of Flexspline Of Harmonic Reducer

Harmonic reducer is a key component in intelligent robots.It has the advantages of high transmission accuracy,small size and light weight,so it is widely used.The harmonic reducer based on the double-arc tooth profile has excellent performance and good application prospects.This paper takes the double-arc harmonic reducer as the research object,combines with the needs of enterprises,uses numerical simulation and fatigue theory to study the stress,deformation and life prediction of the flexspline,and analyzes the influence of related parameters on the life of the flexspline.The main content of this article is as follows.First,according to the needs of the enterprise,combined with the double-arc tooth profile,a cup-shaped harmonic reducer for intelligent robots was designed,including flexspline,rigid gear and cam design,and flexible bearing selection.The transmission relationship of the harmonic reducer is analyzed by the method of mechanism kinematics,and the calculation formula of the harmonic transmission ratio is summarized.The check formula is used to complete the wear resistance check,fatigue strength check and torsional stability check of the flexible wheel,and the rationality of the harmonic reducer design is determined.The model is used as the basis for further research.Secondly,a set of finite element analysis methods for harmonic reducers are provided.Study the relationship between the parts of the harmonic reducer,and use Hypermesh to complete the meshing of the model.Aiming at the difficulty of simulation convergence caused by the initial interference,contact nonlinearity and geometric nonlinearity of the harmonic reducer,the cam is divided into two and the flexspline is first opened in Abaqus and then the rigid gear and flexspline contact is established.The stress in the static state of the flexspline and the stress in the dynamic state are studied.It is found that the maximum Mises stress in the dynamic analysis of the flexspline is increased by 27.5% compared with the maximum Mises stress in the statics.Therefore,it is more reliable to use the dynamic results to evaluate the structural safety.In addition,the neutral layer displacements of the front,middle and rear ends of the flexspline are extracted,and it is found that the displacement changes of each section basically satisfy the periodicity and the amplitude of the displacement change of the front section is the largest.Then,on the basis of simulation,through the transmission ratio relationship between the wave generator and the flexspline,a method of synthesizing the stress of one circle of the flexspline into the periodic stress spectrum of the flexspline is proposed.The stress spectrum of the flexspline is counted by rain,combined with the modified P-S-N curve,the life of the flexspline is calculated using the linear fatigue theory.In order to be convenient to use,this article uses the powerful development function of Matlab to compile the life prediction method of the flexspline into an software.Finally,the influence of the installation distance of the wave generator on the life of the flexspline is studied.The installation range of the wave generator is divided equidistantly,and combined with the finite element simulation method and the fatigue prediction method of the flexspline in this paper.It is found that as the distance between the end face of the wave generator and the front end of the flexspline increases,the life span of the flexspline increases.The optimal installation distance of the wave generator is 1.5mm.In addition,the influence of the length-diameter ratio of the flexspline on the life of the flexspline is also analyzed,and it is found that the larger the length-diameter ratio,the longer the life of the flexspline is within the range of the obtained length-diameter ratio.The above results have certain guiding significance for the structural design of the flexspline.