Pages 173-174
A new surface mount system that is composed of many miniature manipulators has been proposed as a means of system down-sizing. The miniature manipulator consists of a molded pantograph mechanism, which has large deflective flexure hinges and links, both made of the same materials. A complex and dynamic force acts on each flexure hinge in the pantograph mechanism along with motion and vibration of the pantograph mechanism. Then, a dynamic stress state, a combination of bending, tensile, compressive, and shearing stress, is induced within the hinge. We set up a hypothesis that in these stresses, bending and tensile stress are the major factors in the fatigue damage of hinges. On this hypothesis, we carried out a reverse bend test under a static tensile load condition with a hinge specimen as a fatigue test. The hinge specimen is injection molded, and the material is polypropylene, polyethylene, polyamide, and polystyrene. From this test, we investigated the durability of a hinge, frequency relativity to the durability of the hinge, and the advance in damage inside of the hinge.
