Analysis Of The Kinematic Accuracy Reliability Of Mechanism With Joint Clearances And Flexibilitycoupling

Clearances and elastic deformation of flexible bodies are inevitable in practical mechanisms. However, in nature, the existence of these clearances causes impact forces, creating increasing vibration amplitude. Meanwhile, the elastic deformation of flexible bodies leads to the decline in kinematic accuracy. Besides, the coupling effect between clearances and flexible component elastic deformation further has a significant influence on kinematic and dynamic characteristics of mechanism, and the coupling effect not only reduces stability, working accuracy and reliability of mechanical system, but also increases wear rate rapidly. Therefore, taking account of the coupling effect in joints of mechanical system inevitably, this paper researched on the coupling dynamic characteristics and kinematic accuracy reliability of mechanism with joint clearances and flexibility, which can provide theoretical guidance for further analysis of friction, wear and reliability of mechanism with joint clearances and flexibility.Considering joint clearances of mechanism, the vector model and mathematical model of joint clearance are constructed initially in this study, and the normal collision force model and tangential friction force model are derived and analyzed subsequently. Then, the two force models are introduced to the flexible multi-body dynamics model based on multi-body dynamics theory. Hereby, the coupling dynamics model of mechanism with clearance and flexible component is established. According to the coupling dynamics model, the Monte Carlo method is used for reliability model of the kinematic accuracy of the mechanism, which laies a foundation for the following research of coupling dynamic characteristics and reliability analysis.Next, considering the slider-crank mechanism with clearances, the virtual prototype model of planar slider-crank with two joint clearances is constructed through the software of ADAMS. Then, the dynamic characteristics and kinematic accuracy of mechanism with joint clearances are studied and analyzed with the case of different clearance sizes, quantity and crank velocities. Furthermore, based on the research above, the dynamic characteristics are analyzed quantitatively by using dimensionless root mean square error effect index which is proposed in this study.In addition, a flexible dynamic model is derived, in which flexible linkage is taken into account. And then a finite element model of flexible linkage is given to obtain each natural frequency and mode shape with the finite element analysis software of ANSYS. Hereby, the elastic deformation law is studied reasonably by analyzing the effect of crank velocities and Elastic Modulus on the flexib le linkage. According to the research above, the dynamic characteristics and kinematic accuracy of the rigid-flexible coupling mechanism are analyzed.Finally, based on the research above, an experimental planar slider-crank mechanism with two clearances and flexible link has been set up, which is used to obtain some experimental data in order to verify and validate the coupling dynamic model and reliability model of the mechanical system. From the experimental and simulation dynamic characteristic outcomes reported in this paper, the dynamic characteristics are studied quantitatively and kinematic accuracy reliability of mechanism is analyzed properly based on the models established. It is concluded that the coupling dynamics model and kinematic accuracy reliability model of mechanism with clearance and flexible component are verified and validated through experiment and simulation.