Purpose
– The purpose of this paper is to introduce a novel method for developing static aeroelastic models based on rapid prototyping for wind tunnel testing.
Design/methodology/approach
– A metal ...frame and resin covers are applied to a static aeroelastic wind tunnel model, which uses the difference of metal and resin to achieve desired stiffness distribution by the stiffness similarity principle. The metal frame is made by traditional machining, and resin covers are formed by stereolithgraphy. As demonstrated by wind tunnel testing and stiffness measurement, the novel method of design and fabrication of the static aeroelastic model based on stereolithgraphy is practical and feasible, and, compared with that of the traditional static elastic model, is prospective due to its lower costs and shorter period for its design and production, as well as avoiding additional stiffness caused by outer filler.
Findings
– This method for developing static aeroelastic wind tunnel model with a metal frame and resin covers is feasible, especially for aeroelastic wind tunnel models with complex external aerodynamic shape, which could be accurately constructed based on rapid prototypes in a shorter time with a much lower cost. The developed static aeroelastic aircraft model with a high aspect ratio shows its stiffness distribution in agreement with the design goals, and it is kept in a good condition through the wind tunnel testing at a Mach number ranging from 0.4 to 0.65.
Research limitations/implications
– The contact stiffness between the metal frame and resin covers is difficult to calculate accurately even by using finite element analysis; in addition, the manufacturing errors have some effects on the stiffness distribution of aeroelastic models, especially for small-size models.
Originality/value
– The design, fabrication and ground testing of aircraft static aeroelastic models presented here provide accurate stiffness and shape stimulation in a cheaper and sooner way compared with that of traditional aeroelastic models. The ground stiffness measurement uses the photogrammetry, which can provide quick, and precise, evaluation of the actual stiffness distribution of a static aeroelastic model. This study, therefore, expands the applications of rapid prototyping on wind tunnel model fabrication, especially for the practical static aeroelastic wind tunnel tests.
•An integrated plastic shell structure, made of Additive Manufacturing, that contributes partial stiffness, is proposed in the paper. The structure can make the model have better performance in ...geometrical similarity and stiffness similarity.•The stiffness design of the model is formulated as a constrained single-objective optimization problem, based on which an aeroelastic model with an integrated resin shell is designed, calibrated, and tested on the ground and in the wind tunnel.
The wind tunnel test of static aeroelastics is a basic method to study the static aeroelastic phenomena of aircraft and other similar structures. As the test objects, the static models need to meet similar requirements, such as geometric similarity and stiffness similarity. The traditional models adopt a spar-frame-skin hybrid structure. The multiple frame segments (skins) of the models are separated from each other, and it is difficult to ensure the geometrical similarity of the aerodynamic shapes of the models during the tests. The overall stiffness of the models with this structure is borne by the metal spars, which makes it difficult to design and manufacture the models. Replacing the segmented frame/skins in the hybrid structure, an integrated shell structure made of additive manufacturing technology (AM) that contributes partial stiffness is proposed in this paper. Based on the structure, a static aeroelastic model is designed in two phases: the similarity design and stiffness design. The stiffness design is formulated as a constrained single-objective optimization problem, and the gradient-based optimization algorithm is adopted to implement the optimization to obtained structural dimensions of the model in the hybrid structure. The errors of the stiffness design are checked and the contribution of integrated shell to the overall stiffness is discussed. A large-aspect-ratio aircraft is chosen as the prototype and a static aeroelastic model with the integrated resin shell is designed, calibrated, and tested in this paper. The results show that the static aeroelastic model with the proposed AM integrated shell is feasible and can be used to study the static aeroelastics reliably and efficiently.
