Design and Analysis of Displacement amplifier in compliant Mechanism using topology optimization

Author(s): P. Gopal, Azhagiri Pon

Abstract: The thesis deals with Displacement-amplifying Compliant Mechanisms (DaCMs), which use the input displacement applied at a point to a give amplified output displacement at another point with a single elastic continuum. We developed a spring-mass-lever model to capture the static and dynamic behaviour of DaCMs. We used this model for evaluating the topologies of DaCMs for sensor applications based on several criteria, and used a combined figure of merit for selection. When none of the DaCM topologies in the database are able to meet all the requirements of a new sensor, we synthesize a new DaCM using topology optimization. This involves nonlinear constraints that were linearized to incorporate them into the optimality criteria method, which is used to solve the topology optimization problem. Two applications of DaCMs, namely, a bulk micro machined high-resolution accelerometer and a minute mechanical force sensor are pursued in this work. The addition of a DaCM to a micro machined accelerometer increases the sensitivity along the intended axis by an order of magnitude or more. But it has the undesirable side-effect of increasing the cross-axis sensitivity. We overcame this problem by a structural modification, and topology optimization that includes a constraint on the cross-axis sensitivity.