A comparative analysis of joint clearance effects on articulated and partly compliant mechanisms

Clearance is inevitable in the articulated mechanisms due primarily to the design, manufacturing and assembly processes or a wear effect. This phenomenon affects the kinematic and dynamic performances of mechanism negatively. Compliant mechanism, which consists of at least one flexible member along with the conventional rigid links, becomes a favorable choice to decrease the number of movable joints and also their clearance effects. In this study, conventional and compliant slider-crank mechanisms having joints with clearance are used to investigate and compare the effects of joint clearance. Pseudo-rigid-body model of compliant mechanism is constituted. For the case of different clearance sizes and running speeds, kinematic and dynamic performances of mechanisms are compared to each other. The results show that the joint clearance leads to chaotic behavior on kinematic and dynamic outputs of mechanism. The flexibility of small-length flexural pivot, that is, pseudo-joint, has clear suspension effects to decrease the undesired reflections of joints clearance on the system outputs. Also, this pseudo-joint constitutes a force-closed kinematic pair behavior between journal and bearing in joint having clearance. This leads to continuous contact mode by preventing the separation of journal and bearing parts.