By utilizing a damping perturbation method, the present g-method includes a e rst-order damping term in the e utter equation that is rigorously derived from the Laplace-domain aerodynamics. The g-method generalizes the K-method and the P ‐K method for reliable damping prediction. It is valid in the entire reduced frequency domain and up to the e rst order of damping. The g-method utilizes a reduced-frequency sweep technique to search for the roots of the e utter solution and a predictor-corrector scheme to ensure the robustness of the sweep technique. The solution algorithm of the g-method is proven to be efe cient and robust and can obtain an unlimited number of aerodynamic lag roots, as demonstrated by the results of the selected test cases.

Damping Perturbation Method for Flutter Solution: The g-Method

Active flutter suppression, which is a part of the group of flight vehicle technologies known as active controls, is an important contributor to the effective solution of aeroelastic instability pr...

https://arc.aiaa.org/doi/pdf/10.2514/1.C034442

Aircraft Active Flutter Suppression: State of the Art and Technology Maturation Needs

The interactions of lightweight flexible airframe structures, steady and unsteady aerodynamics, and wide-bandwidth active controls on modern airplanes lead to considerable multidisciplinary design challenges. More than 25 years of mathematical and numerical methods' development, numerous basic research studies, simulations and wind-tunnel tests of simple models, wind-tunnel tests of complex models of real airplanes, as well as flight tests of actively controlled airplanes, have all contributed to the accumulation of a substantial body of knowledge in the area of aeroservoelasticity. A number of analysis codes, with the capabilities to model real airplane systems under the assumptions of linearity, have been developed. Many tests have been conducted, and results were correlated with analytical predictions. A selective sample of references covering aeroservoelastic testing programs from the 1960s to the early 1980s, as well as more recent wind-tunnel test programs of real or realistic configurations, are included in the References section of this paper. An examination of references 20-29 will reveal that in the course of development (or later modification), of almost every modern airplane with a high authority active control system, there arose a need to face aeroservoelastic problems and aeroservoelastic design challenges.

Integrated Aeroservoelastic Optimization: Status and Direction

Flutter and post-flutter constraints in aircraft design optimization

The synthesis of actively controlled composite wings is formulated as a multidisciplinary optimization problem. A unique integration of analysis techniques spanning the disciplines of structures, aerodynamics, and controls is described. A rich variety of behavior constraints can be treated including stress, displacement, control surface travel and hinge moment, natural frequency, aeroservoelastic stability, gust response, and handling quality constraints, as well as performance measures in terms of drag/lift coefficients, drag polar shape, required load factor or roll rate, and wing mass. The design space includes a simultaneous treatment of structural, aerodynamic, and control system design variables. The paper sets the stage for multidisciplinary wing optimization by describing the capabilities and discussing the accuracy of the analysis and related behavior sensitivity analysis. Applicability of approximation concepts to the multidisciplinary optimization problem is examined by studying typical aeroservoelastic stability, gust response, and performance-related constraints. The computational efficiency of the combined analysis and sensitivity as well as the quality of key behavior constraint approximations indicate that single-level optimization of composite, actively controlled practical wings is within reach.

W. P. Rodden

Papers

Aerodynamic lag functions, divergence, and the British flutter method