Fatigue testing of flexure hinges for the purpose of the development of a high-precision micro manipulator

Abstract. An approach was initially proposed for the estimation of the maximum von Mises stress in flexure hinges. It relied on recognizing relevant stress factors that were calculated from empirical functions set up by using the finite element method. Afterwards, a fatigue test bench was designed and realized for the examination of flexure hinge specimens. As functional failure occurred before fracture, crack initiation and propagation were observed permanently with the help of a monitoring system and sporadically by means of scanning electron microscopy. On the basis of results obtained thereby, where varying the maximum rotation angle, the operating frequency and the quality of the notch surfaces, a correlation was established between the stress limit and the number of cycles up to functional failure. This was utilized for the optimal dimensioning of flexure hinges within the framework of the development of a high-precision micro manipulator.