Flutter Analysis of Aerostructures Test Wing with Test Validated Structural Dynamic Model

Fluid-Structure Modeling and Simulation of a Modified KC-135 Icing Tanker Boom

“…It is important to stay within the ±3% error military specification 8,9 for cases involving flutter where a small error in mode frequency can drastically alter the flutter boundary. 10 Owing to the geometric and material nonlinearities in the AIT boom system, this modal model does not meet that specification for all configurations, but is sufficient for simulations where the goal is not to simulate divergence or flutter-like phenomena of the boom. In order to confirm that the modal vectors from the FE model are in good agreement with those measured from the GVT, a modal assurance criteria (MAC) was used.…”

Creating a Test-Validated Finite-Element Model of the X-56A Aircraft Structure

“…(15) and (16), were performance indices instead of using a single norm value of off-diagonal terms as in Eq. (17), which was used in the previous version of the modeltuning tool [2,16]. With the extended version, it was much easier to improve each off-diagonal term element as opposed to the previous version.…”

“…This tuning and adaption procedure has become an accepted and necessary step in making models more reliable; however, it cannot handle or eliminate all uncertainties in a finite-element (FE) model. To minimize the uncertainties in aeroelastic as well as aeroservoelastic response computations, the structural dynamic model, the unsteady aerodynamic model, and the actuator model should be validated with respect to the corresponding test data [2,3]. Small modeling errors in an FE model will eventually induce errors in the structural flexibility and mass, thus propagating into unpredictable errors in the unsteady aerodynamics and the control law design.…”

“…Supporting the ARMD guidelines, NASA AFRC has developed a computer code for FE model tuning [2,16] using the object-oriented optimization (O 3 ) tool [17] together with Nastran [18], an FE analysis computer software program. Three optimizer algorithms have been incorporated into the O 3 tool: design optimization tools (DOTs) [19], based on a gradient-based algorithm; the genetic algorithm (GA) [20], which is a class of stochastic and global optimization; and bigbang-big-crunch algorithms [21][22][23][24].…”

“…Based on the validated model, flutter boundaries are computed again and compared with results obtained from the nonvalidated model. The secondary objective of this study is to improve and extend the previously developed structural dynamic FE model-tuning tool [2] and demonstrate this tool using the X-56A aircraft as a sample case.…”