Stiffness Compensation Through Matching Buckling Loads in a Compliant Four-Bar Mechanism

A. Numic, T. W.A. Blad*, F. van Keulen

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

3 Citations (Scopus)
8 Downloads (Pure)


In this paper, a novel alternative method of stiffness compensation in buckled mechanisms is investigated. This method involves the use of critical load matching, i.e., matching the first two buckling loads of a mechanism. An analytical simply supported five-bar linkage model consisting of three rigid links, a prismatic slider joint, and four torsion springs in the revolute joints is proposed for the analysis of this method. It is found that the first two buckling loads are exactly equal when the two grounded springs are three times stiffer than the two ungrounded springs. The force–deflection characteristic of this linkage architecture showed statically balanced behavior in both symmetric and asymmetric actuation. Using modal analysis, it was shown that the sum of the decomposed strain energy per buckling mode is constant throughout the motion range for this architecture. An equivalent lumped-compliant mechanism is designed; finite element and experimental analysis showed near-zero actuation forces, verifying that critical load matching may be used to achieve significant stiffness compensation in buckled mechanisms.

Original languageEnglish
Article number021007
Number of pages9
JournalJournal of Mechanisms and Robotics
Issue number2
Publication statusPublished - 2022

Bibliographical note

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  • Buckling
  • Compliant mechanisms
  • Mechanism design
  • Mechanism synthesis
  • Static balancing


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