Stress relaxation insensitive designs for metal compliant mechanism threshold accelerometers

Abstract

a b s t r a c tWe present two designs for metal compliant mechanisms for use as threshold accelerometers which require zero external power. Both designs rely on long, thin flexures positioned orthogonally to a flat body. The first design involves cutting or stamping a thin spring-steel sheet and then bending elements to form the necessary thin flexors. The second design uses precut spring-steel flexure elements mounted into a mold which is then filled with molten tin to form a bimetallic device. Accelerations necessary to switch the devices between bistable states were measured using a centrifuge. Both designs showed very little variation in threshold acceleration due to stress relaxation over a period of several weeks. Relatively large variations in threshold acceleration were observed for devices of the same design, most likely due to variations in the angle of the flexor elements relative to the main body of the devices.

Low frequency Vibration Energy Harvester using Compliant Mechanism driven Rosen-type Piezoelectric Transformer

“…The tuned 3D model is now being used in Comsol Multiphysics to examine the structure's frequency driven dynamic behaviour. The exterior body of the present structure has been tested with three different materials (acrylic plastic [16], structural steel [17], and Aluminium alloy AL 6061 T6 [7].…”