Selective Amplification and Suppression of Strain in a Multi-Axis Force Sensor Using Topology Optimization

Abstract This paper proposes an innovative conceptual design of a wind tunnel balance axial section using topology optimization. A wind tunnel balance is a sensor that measures six force/moment components from a wind tunnel model. It is also a structural link between the wind tunnel model and supporting hardware. An axial section, one of the six measurement sections in the balance, is difficult to design because it is often required to resolve an axial force which is much smaller than other force components. Topology optimization is used in this paper to obtain a non-intuitive conceptual design of an axial section. To realize the design requirements, a new top-down symmetric design formulation is suggested to amplify the gauge reading under a small axial loading and to suppress the gauge reading under nonaxial loadings. The formulation assumes the use of a conventional full Wheatstone bridge circuit. The projection method is extensively used to consider manufacturing uncertainties. Then, a postprocessing strategy is used to generate a manufacturable geometry. The postprocessing leverages the Multi-Objective Genetic Algorithm function in ANSYS Workbench to ensure the design requirements of the balance structure are met while maintaining a smooth geometry profile. Satisfactory sensing performance is verified from the postprocessed model using commercial FEM software.