A comparative overview of strain actuated surfaces' design

In this paper two different approaches to design of strain actuated lifting surfaces are compared with each other and with a classical aeroelastic tailoring method. Piezoelectric actuation is accomplished by piezo-patches embedded in the wing's composite lay-up and piezoelectric ribs (piezo-ribs) placed spanwise. If the piezoelectric patches are isotropic in their plane they can not directly induce any twist effect in the wing. Thus, in this case, the wing can undergo twisting only as an effect of the coupling (due to tailoring and wing sweep angle) between bending and twisting torques. When piezoelectric patches are used, this configuration is not yet the most effective one. In fact, the largest electromechanical coupling coefficient, which is the one in the direction of the applied electric field, is not thoroughly exploited. On the other hand, piezo-ribs are able to induce not only bending but also pure twisting deformation and exploit the largest electromechanic coupling effect so they may provide the designer with a higher control authority. However, this kind of control involves larger weight. In this paper, aeroelastic wing performance for these different configurations is analyzed. Moreover, the comparison is also made in terms of energy consumption. Numerical examples complete the work.