A four-node composite facet-shell element is developed, accounting for electromechanical coupling of Macrofiber Composite (MFC) and conventional PZT patches. Further a warping correction is included in order to capture correctly the induced strain of conformable MFC, surface bonded on a cylindrical shell. The element performance to model the relations between in-plane electric field to normal strains is examined with the help of experiment and ANSYS analysis. In ANSYS, a simple modeling scheme is proposed for MFC using a parallel capacitors concept. The independent modal space control technique has been revisited to address the control of combination resonances through a selective modal space control scheme, where two or more modes can be combined to form the vibrating system or plant in modal domain. The developed control schemes are implemented in a digital processor using DS1104 and the closed-loop vibration control experiments are conducted on a CFRP shell structure. The influence of directionally induced actuation of MFC actuators on elastic couplings of composite shell is studied theoretically and is subsequently demonstrated in experiments. MFC actuators provide the much needed optimization domain for achieving the vibration control of combination resonances of elastically coupled deep-shell structure. 1. Introduction Active control techniques are becoming more popular in recent years due to the emergence of a field called “Smart Materials and Structure.” Smart materials such as piezoelectric, shape memory alloys, and magnetostrictive have got multi functional behaviors, namely, actuation, sensing, and load carrying. Among these, the electromechanically coupled piezoelectric materials possess immense potentials because of its dynamic characteristics (wider frequency band, large force) and their availability in different forms (bar, patch, composite, stack, etc.). Piezoelectric patches and composites such as Macrofibre Composite (MFC), Active Fibre Composite (AFC) are increasingly considered as actuators by research communities to address various vibration control-related problems in recent years [1–7]. Shell structures are commonly adopted in aerospace vehicles [8]. The wing panels, fuselage outer skins, tail panels, and so forth are constructed with shell structural elements using aluminum and composite materials. Light weight aerospace, naval and civil engineering structures usually employ shell configurations to attain structural efficiencies such as improved stiffness, desired shape, optimal weight, and aeroelastic characteristics. Although
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