Over-constraint is an important concern in mechanism design because it can lead to a loss in desired mobility. In distributed-compliance flexure mechanisms, this problem is alleviated due to the phenomenon of elastic averaging, thus enabling performance-enhancing geometric arrangements that are otherwise unrealizable. The principle of elastic averaging is illustrated in this paper by means of a multi-beam parallelogram flexure mechanism. In a lumped-compliance configuration, this mechanism is… CONTINUE READING
Figures 5 through 7 provide a comparison between the closed-form analysis predications (indicated by solid lines) and FEA results (indicated by circles). The two analyses are found to be in generally good agreement. Fig.5 presents stiffness variation with α, for different degrees of distributed compliance at y=0. Not only is the nominal stiffness greater for small ao, the rate of quadratic increase with α is also higher. For a larger primary displacement, y=0.08, the stiffness variation with α are plotted in Fig.6. This figure illustrates the role of the elastokinematic effect in reliving the stiffness caused by geometric imperfection α. Since the elastokinematic effects are more prominent in distributed compliance topologies, the stiffness is restored to a greater extent in these cases as compared to lumped-compliance topologies. The effect of the non-linear elastokinematic behavior is further illustrated in Fig.7. For a given geometric error, α = 0.008, the primary stiffness drops with increasing primary displacement because the axial or constraint direction compliance of each beam increases.