An Analytical Approach in Dynamic Calibration of Strain Gauge Balances for Aerodynamic Measurements

Strain gauge balances (SGBs) are efficient and accurate means of static force measurement. However, due to their inherent elastic characteristics, they lack desired performance when used in dynamic loading conditions. In this paper, a novel technique is presented that remedies their inherent weakness in measuring dynamic periodic forces. The proposed method produces a correction factor to compensate the measured loading in dynamic situations. For this purpose, first an analytical investigation is performed to determine the structural dynamic behavior of a typical SGB system via the modal approach. This analytical investigation leads to identification of the structural interference effects that occurs on the SGB output in dynamic scenarios and renders the desired validated dynamic correction factor for periodic loading correction. The proposed methodology allows for extraction of the true SGB signal and/or loading out of the complex erroneous SGB output. As a case study, a periodic loading is measured via two different balances and the results are compared with and without taking into account the correction factor. The result of this investigation demonstrates that the introduced correction factor plays a crucial role in dynamic force estimation, especially when the loading frequency approaches the natural frequencies of the balancing system structure.