Dynamics analysis of 2-DOF complex planar mechanical system with joint clearance and flexible links

Tang

2020

Self Cite

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.

“…where α � 50 and β � 50 are the stability coefficients and _ Φ � dΦ/dt. According to the literature [7], a stable dynamic equation is obtained and can be expressed as…”

Section: Shock and Vibrationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

Tang

2020

Self Cite

“…Nine-Bar Mechanism with Mixed Clearances e 2-DOF nine-bar mechanism is assembled of frame, cranks 1 and 4, links 2, 3, 6, and 8, triangular member 7, and slider 9. Link 5 is frame [43]. Crank 1 and link 2 are linked by a revolute clearance pair A. Crank 4 and link 3 are linked by a revolute clearance pair B. Translational clearance is directly related with the slider, which is denoted by C. erefore, clearances at A, B, and C can better reflect impact of clearances on dynamic response.…”

Section: Establishment Of Dynamics Model Of 2-dofmentioning

confidence: 99%

Dynamic Responses of Planar Multilink Mechanism considering Mixed Clearances

Jiang

Deng

2020

Self Cite

Translational and revolute joints are the main kinds of joints in planar multilink mechanisms. Translational and revolute clearance joints have great influence on dynamical responses of planar mechanisms. Most research studies mainly focused upon revolute clearance of planar mechanisms based upon the modified Coulomb friction model, some studies investigated clearance of the pinslot joint, and few studies researched mixed clearances (considering both translational clearance and revolute clearance) based on the LuGre friction model. Dynamic response of the 2-DOF nine-bar mechanism considering mixed clearances based on the LuGre model is investigated in this work. e dynamic model with mixed clearances is built by the Lagrange multipliers. Dynamic responses including motion output of the slider, driving torques, contact forces, shaft center trajectories at revolute clearance pairs, and slider trajectory inside the guide are analyzed, respectively. Influences of different friction models on dynamic responses are studied, such as LuGre and modified Coulomb's friction models. Effects of different clearance values and different driving speeds on dynamic responses with mixed clearances are both analyzed. Virtual prototype model considering mixed clearances is carried out through ADAMS to verify correctness.

“…A 2-DOF nine-bar mechanism is taken as a research object, which consists of the frame, crank 1, rod 2, rod 3, crank 4, rod 6, triangular panel 7, rod 8, and slider 9. Rod 5 is frame [15]. Two cranks are driven by the motors, and the DOF of mechanism is 2.…”

Section: Dynamic Model Of 2-dof Nine-bar Mechanism Considering Revolumentioning

confidence: 99%

“…rough utilizing Poincaré maps, periodic responses and chaotic responses for the four-bar mechanism were both observed. Chen et al [15] developed the nonlinear dynamic model for 2-DOF nine-bar mechanism containing clearance and flexibility rods through using the Lagrange equation and FEM. Yaqubi et al [16] analyzed dynamics behavior of a crank-slider mechanism containing clearance pairs and investigated nonlinear dynamic by Poincaré maps and bifurcation diagrams.…”

Section: Introductionmentioning

confidence: 99%

Dynamic Response Analysis of Planar Multilink Mechanism considering Wear in Clearances

Jiang

Deng

2019

Self Cite

Clearance wear is one of the factors that affects dynamics for mechanical systems. A numerical methodology suitable for modeling and calculation of wear at multiple revolute clearance pairs in the field of the planar multilink mechanism is proposed. In this paper, the 2-DOF nine-bar mechanism considering two revolute clearance joints is regarded as the study object. Normal contact force and friction force models of revolute clearance joints used Lankarani–Nikravesh (L-N) and LuGre models, respectively. The iterative wear prediction process based upon Archard’s model has been applied to calculate wear characteristics. The wear prediction procedure is integrated with multibody dynamics, wear depths at revolute clearance joints are calculated, and the surface of shaft and bearing is reconstructed twice. The dynamic responses of mechanism considering two nonregular revolute clearances caused by wear are studied in depth. The nonlinear characteristics of the mechanism after wear are studied by the phase diagram and Poincaré map. Influences of different initial constant clearance values and different driving speeds on wear of two revolute joints are also researched. The results show that it is necessary to consider the factor of irregular clearances caused by wear in analysis of dynamics of precision mechanisms. Initial constant clearance values and driving speeds have some influence on wear phenomenon. This research provides a theoretical basis for studying dynamics of the planar multilink mechanism considering wear in multiple clearances.