Abstract

The main goal of this work is to develop a comprehensive methodology for predicting wear in planar mechanical systems with multiple clearance joints and investigating the interaction between the joint clearance, driving condition, and wear. In the process, an effective contact surface discretization method together with the Lagrangian method are used to establish the dynamic equation of the multibody system. Considering the change of the contact surface, an improved nonlinear contact force model suitable for the complicated contact conditions is utilized to evaluate the intrajoint forces, and the friction effects between the interconnecting bodies are discussed using the LuGre model. Next, the contact forces developed are integrated into the Archard model to compute the wear depth caused by the relative sliding and the geometry of the bearing is updated. Then, a crank slider mechanism with multiple clearance joints is employed to perform numerical simulations in order to demonstrate the efficiency of the dynamic procedures adopted throughout this work. The correctness of the proposed method is verified by comparing with other literature and simulation results. The results show that the wear is sensitive to different initial conditions, and the evolving contact boundary makes the dynamics of mechanical system and the joint wear prediction more complex. This study is helpful for predicting joint wear of mechanical systems with clearance and optimizing the mechanism’s design.

Highlights

  • The previous research on wear is mainly focused on how to embed the wear model into the dynamic equations of the multibody system, which mainly involves the calculation of contact stresses, the determination of the incremental wear amount and the updating of geometry

  • In view of this a modified nonlinear continuous contact force model based on the Flores model [51] and an improved Winkler elastic foundation mode [54] is utilized to evaluate the impact force developed in the clearance joint, which is suitable for complex contact conditions

  • The method consists of two parts: dynamic analysis and wear prediction

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Summary

Introduction

Different components are connected by elements like hinges to allow them to rotate with respect to each other. The complex and variable contact surface between two contact bodies due to wear will make it difficult to establish and solve the dynamic model of revolute joint with clearance accurately, which will aggravate the nonlinear characteristics of multibody system and make it more likely to exhibit chaotic behavior. It is necessary to investigate the coupling between the dynamic characteristics and wear process of multi-body system with clearance, and to calculate the impact force under the nonstandard contact surface using the appropriate contact force model. The wear process and the developed contact forces can be integrated into the equation of motion of the system to observe how the worn surface will affect the wear volume of the bearing profile, and further parameterize the joint wear in the mechanical system, which helps optimizing the mechanism in the design stage for prolonging its life and performance.

Description of revolute joint with clearance
New modeling methods for nonstandard contact surface
Contact force model and friction model
Dynamical model of crank-slide mechanism with one clearance
Dynamical model of crank-slide mechanism with two clearances
Crank slider mechanism with one clearance
Crank slider mechanism with two clearance joints
Simulation verification
Conclusions
Full Text
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