A continuous contact force model of planar revolute joint based on fitting method

Yuntao Li,Zhonghong Li,Zongquan Deng,Qiquan Quan,Dewei Tang

doi:10.1177/1687814017690477

Yuntao Li, Zhonghong Li + Show 3 more

Open Access

https://doi.org/10.1177/1687814017690477

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Abstract

Both the process of eliminating the clearance in joints and the contact–impact process involve movement of a clearance mechanism, which may reduce transmission accuracy and lengthen the response time. An appropriate continuous contact force model is able to describe the contact phenomena of a joint with clearance in a facile manner. However, two main problems still should be solved in building the continuous contact force model. First, the elastic force parts in previous continuous contact force models for a revolute joint were established by amending the force exponent of the Hertz spherical contact model or by the modified Winkler contact model. Nevertheless, the force exponent is usually given by experience, and the thickness of the elastic layer in the Winkler theory is difficult to determine. Second, for the previous damping force parts of a revolute joint, the hysteretic damping coefficients were obtained by substituting the stiffness coefficient with the contact stiffness of revolute joint directly instead of using the energy conservation method for the complicated form of elastic force model. A feasible continuous contact force model based on a fitting method was proposed to avoid these problems. According to the experimental results, the continuous contact force model can be used to predict the contact characteristics of a planar revolute joint in a facile manner.

Highlights

Because of the existence of clearances, the phenomena of contact and separation occur in the joints of a mechanism inevitably, resulting in the following two processes: the eliminating clearance process and the contact–impact process
The contact–impact process may generate a great contact force, which intensifies the instability of the moving mechanism.[1,2,3,4,5]
An appropriate static contact force model based on the elastic half-space theory and the geometric constraint is used as the elastic force portion of the CCF model for a planar revolute joint

Summary

Introduction

Because of the existence of clearances, the phenomena of contact and separation occur in the joints of a mechanism inevitably, resulting in the following two processes: the eliminating clearance process and the contact–impact process. The contact–impact process may generate a great contact force, which intensifies the instability of the moving mechanism.[1,2,3,4,5] The contact–impact force model plays key roles in predicting the contact characteristics of the joints with clearances and reducing the negative influences of clearance joints on the dynamic behavior of the mechanism.[6,7,8,9]. The contact bodies are all considered as truly rigid bodies in the piecewise contact models.[10,11,12]

Objectives

Conclusion