Dynamic Modeling, Response, and Chaos Analysis of 2-DOF Hybrid Mechanism with Revolute Clearances

Abstract

Due to the errors arising from machining or assembly, the deformation during movement, and the wear of movement pairs, the clearance will be generated at the kinematic pair of the mechanism, and the service life or working accuracy of the mechanism is reduced. At present, most of the researches are in a simple mechanism with a single clearance, and there are few papers on the complex mechanism, such as the high-speed mechanism which contains multiple clearances. In order to give a computational methodology for the dynamic modeling and analysis of the planar multilink mechanism with multiple degrees of freedom and multiple clearances and master the dynamic characteristics of the planar multilink mechanism, the nonlinear dynamic models of the multiclearance hybrid seven-bar mechanism under different clearance numbers, different clearance values, different clearance positions, and different driving velocities are established and analyzed. The dynamic output response comparison diagram of the mechanism and the collision force diagrams and center trajectory diagrams of the mechanism at the clearance are given. Then, nonlinear dynamics of the mechanism is studied by different clearance values and driving speeds. The corresponding trajectory phase diagrams, Poincare maps, and bifurcation diagrams are given. The above research results provide an effective theoretical basis for the study about the nonlinear dynamic characteristics of the planar link mechanism with clearance and how to compensate or control the clearances.

Research on dynamic characteristics of transient deployment mechanism with translational clearance joint under large eccentric load

“…As shown in formula (13), the nonlinear contact stiffness coefficient analyzed in this paper is not constant, and the most important factor is the elastic modulus of the contact member. Therefore, the contact stiffness can be changed by changing the elastic modulus of the slider and the guide rail.…”

“…In this paper, on the basis of literature [21], based on formula (13) and the L-N contact force model, a new improved normal nonlinear impact force model is proposed, and its expression is as follows:…”