The existence of clearance causes contact-impact forces in joints, which lead to surface wear and incessant material loss of the joint surface during the motion of mechanisms. In this work, the wear characteristics of dry revolute clearance joints in planar mechanisms are studied using a computational methodology. The normal contact force model and the tangential friction force model are established to describe the contact-impact in clearance joints. Then, the dynamic wear model based on the Archard’s wear model is established to predict the wear characteristics of clearance joints in mechanisms. The dynamic wear depths of clearance joints are obtained in two steps. The first step is the dynamics analysis of mechanisms to obtain the contact and sliding characteristics between the bearing and journal in the clearance joint. The second step is the dynamic wear depth analysis of clearance joints based on dynamic Archard’s wear model. Finally, a planar slider-crank mechanism with two revolute clearance joints between the connecting rod and its adjacent links is used as the implement example. Different case studies are performed to investigate the wear characteristics of clearance joints in mechanical systems.

Due to assembly, wear and manufacturing errors and clearance in the joints are inevitable. When the clearance is introduced into a mechanical system, the impact force in the clearance joint will cause undesirable vibration of the system. In this paper, the dynamic responses of the mechanical system with two revolute clearance joints are studied using computational and experimental methodology. The clearance joint is considered as force constraint. The normal contact force and tangential friction force between the journal and bearing in a clearance joint are modeled using a nonlinear contact force model considering energy loss and a modified Coulomb friction model considering a dynamic friction coefficient, respectively. A planar slider‐crank mechanism with two revolute clearance joints is used to implement the study. The dynamic responses obtained from numerical simulation are compared with the experimental test. Numerical simulations and experimental tests for different clearance sizes and crank speeds are presented and discussed, respectively. The simulation results agree quite well with those of the experiment for different cases, which proves the accuracy and efficiency of the computational method for dynamics analysis of the mechanical system with two revolute clearance joints in this study. The investigation indicates that the clearances in revolute joints significantly affect the dynamic characteristics of mechanical systems, which must be considered in the precision analysis, design, and control of multibody systems, especially for high‐speed machinery.

Clearances in joints are unavoidable due to assemblage, manufacturing errors and wear, which will lead to poor dynamic performances and undesirable vibrations due to impact forces in clearance joints. In dynamics analysis of planar mechanical system, it is usually assumed that the revolute joint is planar joint with radial clearance. However, the axial clearance in the revolute joint and the clearance in the translational joint are ignored. In fact, even planar mechanical systems may exhibit out-of-plane motion due to misalignments. In this work, a planar slider-crank mechanism is used as the example to investigate the effects of mixed clearances on the dynamic responses of planar mechanical system considering radial and axial clearances in spatial revolute joint due to axis misalignment as well as clearance in planar translational joint. The dynamic responses of the planar slider-crank mechanism system with two spatial revolute clearance joints and a planar translation clearance joint are investigated using computational and experimental methodology. The mathematic model of the spatial revolute clearance joint and the planar translational clearance joint are presented. The clearance joints are considered as force constraints and the joint components of an imperfect joint with clearance are modeled as contact bodies. The normal contact force model of clearance joint is established using continuous contact force model. The friction effect is considered using modified Coulomb friction model. Different case studies are presented and discussed to investigate the effects of the mixed clearances on the dynamic responses of the planar slider-crank mechanism.

In the dynamic modeling and simulation of mechanical system with revolute clearance joint, it is usually assumed that the revolute joint is planar joint with radial clearance, but the axial clearance is ignored. In this article, the dynamic responses of a mechanical system considering both radial and axial clearances in 3D revolute clearance joint are investigated using a computational methodology. First, the mathematic model of 3D revolute clearance joint is established considering the radial and axial clearances. The definitions of the radial and axial clearances, the potential contact modes, contact conditions, and contact detection for 3D revolute clearance joint are presented. Furthermore, the normal and tangential contact force models are established to describe the contact phenomenon and determine the contact forces in revolute clearance joints. Finally, two demonstrative application examples are presented to illustrate the dynamic characteristics of mechanical systems considering both radial and axial clearances in revolute clearance joints. A slider-crank mechanism with planar motion and a double pendulum with spatial motion are investigated. Different cases are presented to analyze the dynamic characteristics of a mechanical system considering radial and axial clearances in 3D revolute clearance joints.