Development of wing deflection assessment methods through experimental ground tests and finite element analysis

A set of experimental studies are carried out on a wing of a training aircraft by subjecting it to the static loading and measuring the resulted deflections. The experimental ground tests are initiated by selecting some appropriate points on the lower wing skin in order to apply the loadings. The corresponding points on the upper skin are assigned for the deflection measurements. Through the application of the loadings on a single-point, double-point or triple-point, the deflections of each point on the upper skin are recorded. The ground test results are implemented in the development process of two different techniques for the evaluation of the wing deflections. One technique is based on the Castigliano's theorem, whilst the regression technique is used for the other one. A set of independent deflection equations that can handle all practical flight conditions is proposed by any given technique. In a parallel attempt, the finite element analysis is also carried out and the results are utilized to develop similar wing deflection equations based on the Castigliano's theorem. The outputs of the developed equations are the deflections of the wing based on the independent variables, which in this case are the applied loadings. Eventually, the outputs of the obtained equations are compared for some different loading conditions for the validation purposes. The deflection equations can now be used to calculate the wing deflection distributions for any arbitrary values assigned to the input parameters.