  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.
