A review of various analytical methods and experimental results of supersonic and hypersonic panel flutter is presented. The analytical methods are categorized into two main methods. The first category is the classical methods, which include Galerkin in conjunction with numerical integration, harmonic balance and perturbation methods. The second category is the finite element methods in either the frequency domain (eigensolution) or the time domain (numerical integration). A review of the experimental literature is given. The effects of different parameters on the flutter behavior are described. The parameters considered include inplane forces, thermal loading, flow direction, and initial curvature. Active control of composite panels at supersonic speeds and elevated temperatures is also considered. This review article cites 84 references.

A novel concept is proposed: the use of shape memory alloy (SMA) to reduce panel thermal deflection and flutter responses. SMA has a unique ability to recover large pre-strains completely when the alloy is heated above the austenite finish temperature Af. The transformation austenite start temperature As for nitinol can be anywhere between -60 °F (-50 °C) and +340 °F (+170 °C) by varying the nickel content. During the recovery process, a large tensile recovery stress occurs if the SMA is restrained. The shape memory effect phenomenon is attributed to a change in crystal structure known as a reversible austenite to martensite phase transformation. This solid-solid phase transformation also gives a large increase in Young's modulus and yield stress. In this paper, a panel subject to the combined aerodynamic and thermal loading is investigated. A nonlinear finite element model based on the von Karman strain-displacement relation is utilized to study the effectiveness of an SMA-embedded panel on the flutter boundary, critical buckling temperature, post-buckling deflection and free vibration. The study is performed on an isotropic panel with embedded SMA. The aerodynamic model is based on the first-order quasi-steady piston theory. The dynamic pressure effect on the buckling and post-buckling behaviour of the panel is investigated by introducing the aerodynamic stiffness term, which changes the critical buckling temperature. Panels with SMA embedded in either the longer or shorter direction and either fully or partially embedded are investigated for post-buckling behaviour. Similarly, the influence of temperature elevation on the flutter boundary and vibration frequencies is investigated.

No abstract

No abstract

The anisoparametric three-node MIN6 shallow shell element is extended for modeling Macro-Fiber Composite/Active Fiber Composites (MFCTM/AFC) actuators for active vibration and acoustic control of curved and flat panels. The recently developed MFCTM/AFC actuators exhibit enhanced performance, they are anisotropic and highly conformable as compared to the traditional monolithic isotropic piezoceramic actuators. The extended MIN6 shell element includes embedded or surface bonded MFCTM/AFC laminae. The fully coupled electrical-structural formulation is general and it is able to handle arbitrary doubly curved laminated composite and isotropic shell structures. A square and a triangular cantilever isotropic plates are modeled using the MIN6 elements to demonstrate the anisotropic actuation of a surface bonded MFCTM actuator for coupled bending and twisting plate motions. Steady state modal bending and twisting amplitudes of the cantilever square and triangular plates with MFCTM actuator are compared with the plate’s steady state modal amplitudes with traditional PZT 5A actuator for different angle orientations. Frequency Response Functions (FRF) for the square plate with MFCTM and PZT 5A actuators are also obtained and their actuation performance is compared. The actuation performance of the MFCTM at different locations is also investigated.