Design and performance comparison of double-series and triple-series flexure hinges

The flexible hinge is one of the most important components in lamina emergent mechanisms (LEMs), so the design of a new type of lamina emergent torsional (LET) joint can play a key role in its movement performance. This paper presents double- and triple-series LET flexure hinges, designs the structure of the two hinges, and derives the calculation formula for their bending equivalent stiffnesses. Through theoretical and finite element analyses of the design example, verifies the correctness of the calculation formula for equivalent stiffness. By comparing the bending, tension, and compression performances of the double-and triple-series LET flexure hinges with those of the outside LET flexure hinge, which shares the same outline dimensions of the former, it can be concluded that the triple-series LET flexure hinge can greatly enhance bending performance without any obvious decrease in its tension and compression performances.