A generalized approach for compliant mechanism design using the synthesis with compliance method, with experimental validation

Compliant mechanisms offer numerous advantages over their rigid-body counterparts. The synthesis with compliance technique synthesizes compliant mechanisms for conventional rigid-body synthesis tasks with energy/torque specifications at precision positions. In spite of its usefulness, the method suffers from some limitations/problems. The purpose of this work is to investigate these sensitivities with the synthesis with compliance technique and improve upon existing method. A new, simple but efficient, method for synthesis with compliance using an optimization approach is proposed, and its usefulness and simplicity demonstrated over the existing method. The strongly and weakly coupled system of kinematic and energy/torque equations in the existing method has been studied, and the new method is made simple by removing the strong coupling between these sets of equations. All synthesis cases are solved by treating them as though they are governed by weakly coupled systems of equations. Representative examples of different synthesis tasks are presented. The results are verified with finite element analysis software ABAQUS® and ANSYS® by means of coupler curve/precision position comparisons, and stored energy comparisons. An experimental setup has been devised to perform experiments on compliant mechanisms for validation purposes. The results obtained using the Pseudo-Rigid-Body Model (PRBM) for compliant mechanism synthesis match closely with experimental and finite element analysis (FEA) results, and hence reinforce the utility of the synthesis with compliance method using the PRBM in compliant mechanism synthesis --Abstract, page iii

On a Generalized Approach for Design of Compliant Mechanisms Using the Pseudo-Rigid-Body Model Concept

This paper provides a generalized approach for the design of compliant mechanisms. The paper discusses the implicit uncoupling, between the kinematic and energy/torque equations, enabled by the pseudo-rigid-body model concept, and utilizes it for designing a variety of compliant mechanism types for a wide-range of user specifications. Pseudo-rigid-body four-bar mechanisms, with one to four torsional springs located at the revolute joints, are considered to demonstrate the design methodology. Mechanisms are designed for conventional tasks, such as function, path and motion generation, and path generation with prescribed timing, with energy/torque specified at the precision-positions. State-of-the-art rigid-body synthesis techniques are applied to the pseudo-rigid-body model to satisfy the kinematic requirements. Energy/torque equations are then used to account for the necessary compliance according to the user specifications. The approach utilizes a conventional, simple yet efficient optimization formulation to solve energy/torque equations that allow a designer to i) achieve realistic solutions, ii) specify appropriate energy/torque values, and iii) reduce the sensitivities associated with the \u27synthesis with compliance\u27 approach. A variety of examples are presented to demonstrate the applicability and effectiveness of the approach. All of the examples are verified with the finite element software ANSYS®

On a Compliant Mechanism Design Methodology using the Synthesis with Compliance Approach for Coupled and Uncoupled Systems

Compliant mechanisms are defined as those that gain some or all of their mobility from the flexibility of their members. Suitable use of pseudo-rigid-body models for compliant segments, and state-of-the-art knowledge of rigid-body mechanism synthesis types, greatly simplifies the design of compliant mechanisms. Starting with a pseudo-rigid-body four-bar mechanism, with one to four torsional springs located at the revolute joints to represent mechanism characteristic compliance, a simple, heuristic approach is provided to develop various compliant mechanism types. The synthesis with compliance method is used for three, four and five precision positions, with consideration of one to four torsional springs, to develop design tables for standard mechanism synthesis types. These tables reflect the mechanism compliance by specification of either energy or torque. The approach, while providing credible solutions, experiences some limitations. The method is not yet robust, and research is continuing to further improve it. Examples are presented to demonstrate the use of weakly or strongly coupled sets of kinematic and energy/torque equations, as well as different compliant mechanism types in obtaining solutions