Abstract. Procedure for designing the wind tunnel model of a high aspect ratio (HAR) wing containing geometric nonlinearities is described in this paper. The design process begins with identification of basic features of the HAR wing as well as its design constraints. This enables the design space to be narrowed down and consequently, brings ease of convergence towards the design solution. Parametric studies in terms of the spar thickness, the span length and the store diameter are performed using finite element analysis for both undeformed and deformed cases, which respectively demonstrate the linear and nonlinear conditions. Two main criteria are accounted for in the selection of the wing design: the static deflections due to gravitational loading should be within the allowable margin of the size of the wind tunnel test section and the flutter speed of the wing should be much below the maximum speed of the wind tunnel. The findings show that the wing experiences a stiffness hardening effect under the nonlinear static solution and the presence of the store enables significant reduction in linear flutter speed.
Procedure of conducting an experimental modal analysis (EMA) of roving hammer test for high aspect ratio (HAR) wing containing geometric nonlinearities is presented along with consideration of various tip store sizes. Two sets of test setups of vertical and horizontal arrangements have been considered, which respectively demonstrates the undeformed and deformed cases. Modal properties in terms of natural frequency and mode shape were experimentally measured using the LMS Test.Lab package and the results were then compared between the undeformed and its corresponding deformed configuration. From the finding, it confirms that the chordwise and torsional modes of the undeformed configurations has respectively turned into chordwise-torsion and torsion-chordwise modes as they are in deformed configuration. Meanwhile, the impact related to bending modes is insignificant. Hence, this may result in inaccurate prediction if conventional aeroelastic solution is employed for HAR wing configuration.
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