Compliant mechanism synthesis for shape-change applications: preliminary results

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Compliant mechanism synthesis for shape-change applications: preliminary results

Lu, K.J. / Kota, S.

Most aircraft wings are optimized to produce minimum drag under one particular flying speed, while the flying speed actually varies continuously throughout flight. Although conventional hinged mechanisms can change the wing shape in response to the change in flying speed, the connecting hinges create discontinuities over the wing surface, leading to earlier airflow separation. In this paper, we propose a systematic approach to synthesize compliant mechanisms that can deform an initial curve into a target shape with a smooth boundary. As opposed to the two-step synthesis that separates the interrelated topology and dimensional aspects of a compliant mechanism, we propose an optimization model using a mixed-variable formulation that addresses both aspects simultaneously. The effectiveness of the shape change is evaluated using Fourier descriptors (FDs), which capture the pure 'shape' differences between curves. Due to the discrete nature in the design variables, a genetic algorithm (GA) is employed to find the optimal solution. The preliminary results demonstrate the feasibility of simultaneously addressing the topology and dimensional aspects. They also indicate that the reference shape used for curve description can significantly affect the optimal solutions. This suggests that a more refined objective function is necessary to improve the effectiveness of the results.