Topological synthesis of fluidic pressure-actuated robust compliant mechanisms

TL;DR

This paper develops a robust topology optimization method for designing pressure-actuated compliant mechanisms that are resilient to manufacturing inaccuracies, using a density-based approach with multi-criteria objectives and finite element analysis.

Contribution

It introduces a novel robust density-based topology optimization framework incorporating pressure modeling and multi-criteria objectives for compliant mechanisms.

Findings

Successfully designed inverter, gripper, and contractor mechanisms.

Demonstrated robustness against manufacturing inaccuracies.

Identified limitations of linear elasticity at high pressures.

Abstract

This paper presents a robust density-based topology optimization approach for synthesizing pressure-actuated compliant mechanisms. To ensure functionality under manufacturing inaccuracies, the robust or three-field formulation is employed, involving dilated, intermediate and eroded realizations of the design. Darcy's law in conjunction with a conceptualized drainage term is used to model the pressure load as a function of the design vector. The consistent nodal loads are evaluated from the obtained pressure field using the standard finite element method. The objective and load sensitivities are obtained using the adjoint-variable approach. A multi-criteria objective involving both the stiffness and flexibility of the mechanism is employed in the robust formulation, and min-max optimization problems are solved to obtain pressure-actuated inverter, gripper, and contractor compliant mechanisms with different minimum feature sizes. Limitations of the linear elasticity assumptions while designing mechanisms are identified with high pressure loads. Challenges involved in designing finite deformable pressure-actuated compliant mechanisms are presented.