Design of a crab-like bistable mechanism for nearly equal switching forces in forward and backward directions

A compliant bistable mechanism with a crab-like structure for nearly equal switching forces in the forward and backward directions is developed. It consists of four crab-leg-like beams and a shuttle mass. The crab-leg like beam gives more design freedom than straight beam or curved beam seen in the traditional bistable mechanisms. This design flexibility is exploited here for the design of a bistable mechanism with nearly equal switching forces in the forward and backward directions. Key parameters affect the force-displacement characteristics of the bistable mechanism are identified. The performance of the mechanism is confirmed by experiments. Such a mechanism can be applied in nonvolatile memory devices with two logical levels “1” and “0” assigned to the two stable states which are separated by nearly equal switching forces in back and forth directions.