SUMMARYAn e cient ÿnite element formulation based on a ÿrst-order shear deformation theory (FSDT) is presented for the active control of functionally gradient material (FGM) plates with integrated piezoelectric sensor=actuator layers subjected to a thermal gradient; this is accomplished using both static and dynamic piezothermoelastic analyses. The formulation based on FSDT can be applied to a range of relatively thin-to-moderately thick plates. A constant displacement-cum-velocity feedback control algorithm coupling the direct and inverse piezoelectric e ects is applied to provide active feedback control of the integrated FGM plate in a self-monitoring and self-controlling system. Numerical results for the control of bending and torsional de ections and=or vibrations are presented for a FGM plate comprising zirconia and aluminium. The e ects of constituent volume fraction and the in uence of feedback control gain on the static and dynamic responses of the FGM plates are examined in detail.
SUMMARYIn this paper, a generic ÿnite element formulation is developed for the static and dynamic control of FGM (functionally graded material) shells with piezoelectric sensor and actuator layers. The properties of the FGM shell are graded in the thickness direction according to a volume fraction power-law distribution. The proposed ÿnite element model is based on variational principle and linear piezoelectricity theory. A constant displacement and velocity feedback control algorithm coupling the direct and inverse piezoelectric e ects is applied in a closed-loop system to provide feedback control of the integrated FGM shell structure. Both static and dynamic control of FGM shells are simulated to demonstrate the e ectiveness of the proposed active control scheme within a framework of ÿnite element discretization and piezoelectric integration.
The objective of treating the fractured bone is to achieve painless functioning of the bone and undisturbed healing at the fracture. Internal fixation by stiff bone-plate is one of the standard methods to achieve these objectives. Recently, there is considerable interest in the usage of compliant plates to enhance bone healing with reduced stress shielding. Herein, first an analytical solution is developed to determine screw forces in the bone-plate assembly that conforms the plate and the bone under bending load. Based on the analytical calculations, an optimal fixator plate selection criterion for necessary and sufficient stress shielding is proposed. Second, effectiveness of employing a non-homogeneous stiffness graded (SG) plate rather than a homogeneous stainless steel (SS) plate for stress shielding is investigated using a finite element method. It is found that stress shielding on bone by SG plate is less compared to SS plate.
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