Topology optimization method for wind tunnel balance considering suppression of measurement interference

The strain gauge balance is the core device for accurately measuring aerodynamic loads acting on aircraft models in wind tunnel tests. As a special type of six-component force sensor, its design faces greater challenges due to the constrainted design space, extreme mismatch in load magnitudes across the measured components, and harsh testing conditions. For sting-type balances, the measurement accuracy of the axial force component is inherently limited, as the measuring elements are prone to nonlinear deformation and torsional interference within the restricted design space – problems that are further exacerbated under high load-ratio conditions (e.g., when subjected to large longitudinal loads). To address the interference susceptibility and low accuracy of low-magnitude components under high load-ratios, as well as the limitations of conventional design methods, a topology optimization method considering measurement interference suppression was developed for wind tunnel balances. Based on the interference patterns of axial force measurement, two optimization models- “minimum compliance” and “minimum interference” —were proposed, and a numerical optimization framework integrating the SIMP model, the MMA algorithm, and filtering/projection techniques was established. Multiple design cases were studied using mirrored and non-mirrored design domains strategies, and a prototype was fabricated and calibrated through ground loading tests. Results show that the proposed method yields clear and manufacturable topological configurations; the “minimum interference” model produces simpler and more reliable layouts; the non-mirrored strategy expands the design space but increases manufacturing complexity and computational cost. The fabricated balance exhibits high sensitivity in the target component F_x, with a maximum interference output below 2.3% when other loads are individually applied. The proposed method significantly enhances the anti-interference capability and measurement accuracy of the wind tunnel balance, providing a new approach for the design of high-precision balances and multi-component force sensors.