Nonlinear Dynamic Behaviour of The Mechanisms Having Clearance and Compliant Joints

In this paper, the rigid four-bar linkage with clearance joint has been examined. The effects of design parameters have been analyzed separately. Considering chaotic behaviour and undesirable vibrations of the system induced by joint clearance, it has been suggested to use compliant joints for improving these undesirable behaviours. Therefore, rigid four-bar linkage with clearance joint and compliant joint is investigated by pseudo-rigid-body model. Subsequently, the nonlinear behaviour of the compliant mechanism is examined, using fast Fourier transform analysis, Poincare sections, and bifurcation diagram. Comparative analysis of results clearly shows that using appropriate compliant joints causes notable improvements in the behaviour of the system, reduction of sudden impacts, and lower accelerations. 6 cycles simulations of mechanisms demonstrate the decreasing 207 impacts to 33 impacts using compliant joint. Moreover, the results report 87% decrease in follower top acceleration and 64% in clearance joint top contact force. Although using the compliant joint makes limitations in the workspace, but the appropriate and optimized design of the compliant joint results in good improvement in the performance of the system.