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The reduction method and robust H1 control for uncertain piezoelectric laminated plates with small interval parameters are investigated in this paper. The electromechanical coupling finite element equations of piezoelectric laminated plates are developed based on Hamilton principle. To reduce the high-order uncertain system with small interval parameters, a reduction method is presented by using the balanced model reduction, first-order Taylor expansion, and interval algorithm. Based on the reduction method, a new strategy of robust H1 control design is studied,which includesthe robustH1 controller designofareduceduncertain generalized plantandthe robustness analysisoftheclosedsystemcomposedofthecontrollerandtheoriginaluncertainsystem.Numericalexamplesshow that the reduction method is suitable for a high-order uncertain system with small interval parameters and that the robust H1 control strategy for the uncertain system is feasible and practical.

This paper presents a mixed piezothermoelastic finite element model for a special THUNDER (thin-layer unimorph ferroelectric driver) actuator’s structures. In the mixed piezothermoelastic model, an element includes four displacement nodes, eight temperature nodes, and two potential nodes. Dynamic analyses are implemented to investigate the thermal deformation during the cooling process, deflection caused by the repolarization in the repoling process, and the piezothermoelastic coupling effect in the actuating process. The relationships between these three types of dynamic behaviors are developed by using their initial displacements. Numerical examples are given to demonstrate the proposed model and method. The accuracy of the computational results obtained by using the mixed piezothermoelastic model is sufficient. The THUNDER actuator has good properties on both actuating deflection and resisting load. In engineering applications, thermal strains have a significant effect on dome height, although thermoelectric coupling is relative small but still noticeable. Numerical results show that piezothermoelastic dynamic analysis is necessary for a THUNDER actuator to be used more effectively and accurately.

The reliability-based optimization of active bars' placement and feedback gains of a closed-loop control system for stochastic intelligent truss structural active nonstationary random vibration control is presented. The optimal mathematical model with the reliability constraints on the mean square value of structural dynamic displacement and stress response are built based on the maximization of dissipation energy due to control action, where not only the structural physics parameters, geometric dimensions, and damping are considered as random variables, but also the applied forces are considered as nonstationary random excitation. The numerical characteristics of the nonstationary random responses of stochastic intelligent structure are developed by the random factor method. The rationality and validity of the presented model are demonstrated via an engineering example, and the effect of randomness of the structural parameters on the control performance is also examined.

A new method (random factor method) for the dynamic response analysis of linear stochastic frame structures under nonstationary random excitation is presented. From the expressions of structural random response of the frequency domain, the computational expressions of the mean value, variance, and variation coefficient of the mean square value of the structural nonstationary random displacement and stress response are developed by means of the random variable's functional moment method and the algebra synthesis method, in which the randomness of the structural physical parameters is considered. The influences of the randomness of the structural physical parameters on the randomness of the mean square value of the structural displacement and stress response are inspected via an engineering example.

The overset field-panel method presented solves the integral equation of the time-linearized transonic small disturbance equation by an overset field-panel scheme for rapid transonic aeroelastic applications of complex configurations. A block-tridiagonal approximation technique is developed to greatly improve the computational efficiency to solve the large size volume-cell influence coefficient matrix. Using the high-fidelity computational-fluid-dynamics solution as the steady background flow, the present method shows that simple theories based on the small disturbance approach can yield accurate unsteady transonic flow predictions. The aerodynamic influence coefficient matrix generated by the present method can be repeatedly used in a structural design loop, rendering the present method as an ideal tool for multidisciplinary optimization.

A nonlinear elastic boundary element method (NBEM) approach is developed as an innovative deforming mesh generator for computational aeroelastic simulation. The computational fluid dynamics (CFD) mesh is assumed to be embedded in an infinite nonlinear elastic medium of a hardening material, leading to the formulation of a pseudononlinear elastostatic problem. Whereas the CFD surface mesh is treated as a boundary element model and the CFD flowfield grid as domain sample points, the NBEM approach solves Navier's equations using a particular solution scheme that removes the requirement of the domain integral in the conventional NBEM formulation. The NBEM approach has a unified feature that is applicable to all mesh systems, including unstructured, multiblock structured, and overset grids. An optimization strategy is employed to determine the optimum hardening material properties by minimizing the mesh distortion in the viscous region where grid orthogonality must be preserved. Three test cases are performed to demonstrate the robustness and effectiveness of the NBEM approach for deforming mesh generation.