Two-axis flexure hinges with variable elliptical transverse cross-sections

Flexure hinges are fundamental elements of compliant mechanisms. Therefore, the development of novel primitive flexure hinges is of great value. In this study, the basic structures of notch-type flexure hinges were extended by focusing on their transverse cross-sections, that is, the cross-sections perpendicular to the central axis. A group of primitive flexure hinges with variable elliptical transverse cross-sections (ETC) was developed and investigated. Analytical models for ETC flexure hinges were developed and verified through finite element analyses and experiments. The anisotropic two-axis compliances of the ETC flexure hinges were evaluated using computational analyses. The differences and relations in compliances, rotational precisions, and stresses between the ETC and existing primitive flexure hinges are discussed. An application case of the ETC flexure hinges is presented, which improves the ETC-based compliant mechanisms that can achieve much higher actuation efficiency owing to the simultaneous increase in compliances and decrease in stress concentration. The ETC flexure hinges enhance the design space of the primitive flexure hinges, addressing the knowledge gap between flexure hinges with rectangular and circular transverse cross-sections.