Accuracy Evaluation of PRBM for Predicting Kinetostatic Behavior of Flexible Segments in Compliant Mechanisms

Abstract

The pseudo-rigid-body model (PRBM) method has been widely accepted as one of the most important tools for synthesis and analysis of compliant mechanisms. However, the lack of quantitative study on the accuracy of PRBM for predicting the kinetostatic behavior of flexible members always makes users feel unconfident in the results achieved by PRBM. In this paper, a strain-energy-based approach is proposed for evaluating the accuracy of PRBM for predicting kinetostatic behavior of flexible segments, which compares the results of strain energy calculate using PRBM to those obtained using the derived closed-form solutions. The approach was used to evaluate the accuracy of the PRBM for flexible cantilever beams. It is proved that the PRBM is accurate for modeling segments subject to end-moment loads. A thorough comparison for segments subject to end-force loads is also presented. The results could be useful for PRBM users to assess the accuracy of the models for their compliant mechanism designs, or to choose appropriate values for the characteristic parameters. The results may also be used to improve the PRBM.