Design methodology of a six-component balance for measuring forces and moments in water tunnel tests

Abstract

This article describes the methodology used in the design and evaluation of a new, six-component balance. This balance is used to measure the forces and moments in model tests conducted in the water tunnel at the Iran University of Science & Technology (IUST). To design the structural parameters of the balance, were used derived equations as well as the finite element method in an iterative process. At every step in this process, the dimensions obtained from the derived equations were determined by considering the nominal strain. The finite element method was used to demonstrate the manner in which the strain was distributed and the reliability of the quantities obtained from the derived equations. To evaluate the designed balance, the strain distribution, linearity, stiffness, and the balance’s ability to produce separate component outputs were investigated. The results that were obtained indicating that the designed structure satisfied all the design criteria. A first-order model was used to calibrate the balance. The evaluation of the sensitivity matrix showed that the error that resulted from the effects of the non-linearity associated with the applied loads was less than 0.05%.