Fluid-Structure Optimization of Small-Scale Hydraulic Conduits

Fluid-structure optimization is well-suited for reducing system weight and improving flow efficiency for small-scale hydraulic systems such as for wearable exoskeletons. While single-objective optimization algorithms exist, little work has been done to optimize flow channels under internal and external loads. This study constructed a computational pipeline that connects Open-Source Field Operation and Manipulation (OpenFOAM) to additional software applications to enable fluid-structure topology optimization using the continuous adjoint method. The pipeline was used to optimize the flow path and surrounding structure of small-scale hydraulic conduits with varying bends and external load conditions. We found that the optimized flow path balances path length with curvature to minimize pressure drop. For a non-optimized conduit with a sharp 45-deg bend, the pressure drop was 750 Pa, while the optimized conduit has a pressure drop reduction of 22.5%. Sharp bends create stress concentration points where structural supports are formed, while optimized flow paths reduce stress up to 42.5%, and further distribute support structures. Bending loads can be a restorative force for sharp bends and, therefore, reduce the maximum stress.