Stability Analysis for Compliant Constant-Force Compression Mechanisms

Stability analysis in compliant mechanism (CM) design is of utmostimportance. From a practical point of view, a CM that is unstable is of nosignificance (has no practical value). Three useful plots were considered in theevaluation of each of the dynamic models of nine configurations of compliantconstant-force compression mechanisms (CCFCMs) for their stabilitycharacteristics, which includes the polar plot based on the Routh-Hurwitzstability criterion, the Bode plot, and the Nyquist diagram which considersstability in the real frequency domain. Frequency-domain stability criterion isvery useful for determining suitable approaches to adjusting the CCFCMparameters in order to increase its relative stability. The results obtained showthat the CCFCMs investigated do exhibit higher relative stability for highervalues of damping ratio, and for zero damping ratio, all the CCFCMsinvestigated were unstable. The result also show that for the CCFCMsinvestigated to be stable, damping ratio must be greater than 0.03 (ξ > 0.03)and depending on what attributes are most desirable, the CCFCM parameterscan be optimized to achieve the desired results. Nyquist criterion provides uswith suitable information concerning the absolute stability and furthermore,can be utilized to define and ascertain the relative stability of a system.