Geometrical nonlinearity of high aspect ratio wing and validation via videogrammetric measurement technique

The high aspect ratio (HAR) wing aircraft design has significant advantages due to its high lift characteristics with less-induced drag. However, its high flexibility leads to larger deformation and inexplicit geometrical nonlinear response. The nonlinear effects must be prudently determined to predict the behaviour of HAR wing. Despite the development of nonlinear geometrical model, HAR wing has been infrequently validated. Previous experimental studies mostly focused on the contact method and this technique is not reliable to HAR wing since it will alter the mass and stiffness of the structure. Addressing that, this study proposed a non-contact method using videogrammetric measurement technique to examine the geometrical nonlinearity effects. Ultrahigh-speed camera was used for motion capture and a novel approach using z-indicator was proposed to measure wing deformation. All experimental data were validated through the conventional finite element. A larger wing deflections were found proportionate with the longer wingspan. The high percentage difference between linear and nonlinear static analyses reaffirmed the significant need to consider geometrical nonlinear effects. Moreover, the comparison data recorded (low) percentage error of less than 10% for each aspect ratio. With that, the current study successfully developed an applicable novel technique for the measurement of HAR wing deflection.