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Carlos E. S. Cesnik
Visiting Associate Professor
of Aeronautics and Astronautics
from the University of Michigan

With the increasing complexity of aerospace systems, the engineer has fewer opportunities to gain experience and insight from previous projects. Therefore, computer simulation is a major avenue for training and decision-making support in the design of future aerospace structural concepts. Those structures will most likely be nonhomogeneous, anisotropic, and composed of passive and active materials. New approaches will have to address the complexities inherent to the actual structure while providing the computational characteristics necessary for their integration in a multidisciplinary environment. With this in mind, Professor Cesnik's main research interests are in the general field of structural mechanics, structural dynamics, and aeroelasticity, with emphasis on design-oriented methodologies, as reflected in the following activities.

Wing Structural Modeling:
Development of high-fidelity models of built-up wing structures for structural dynamics/aeroelastic applications. Aeroelastic analysis is an essential part of any aircraft
multidisciplinary design. The structural model used to discretize the wing and other components of the aircraft is usually a combination of plates, membranes, rods, shear panels, etc. However, this type of discretization, while accounting for some details of the aircraft component, results in high mesh preparation time and high computational costs. A new plate-like finite element is envisioned that will asymptotically characterize the behavior of the original three-dimensional built-up cell with fewer degrees of freedom and much simpler topology. At the end, relations are sought for stress/strain recovery at any point of the original structure.

Aeroelastic Model for Control Design:
High-fidelity low-order aeroelastic models are pursued to provide the ideal representation of the aircraft for robust control design. The perfect match between the structural and aerodynamic models allows for a reduced order model while preserving the fidelity required to characterize the aircraft plant.

Active Helicopter Blade Modeling:
Modeling of beam- and plate-like nonhomogeneous, anisotropic structures with the presence of active materials as sensors and actuators. The use of active materials embedded in a composite structure provides a means of actively controlling its behavior, though increasing the complexity of its analysis even more. Since most aircraft structural components have one (beam-like) or two (plate-like) dominant dimensions, specialized theories can be developed to systematically account for all the important three-dimensional (3-D) effects present on those structures. The designer would not have to bear either the cost of 3-D finite element discretization or the loss of accuracy inherent in any simplified representation of the actual structure. Examples of such application are vibration reduction and control augmentation of helicopter rotor blades.

Aeroelastic Interface:
Development of finite-element-like approaches for data interface. In the area of Computational Aeroelasticity, there is the issue of data communication between disciplines. The growing use of Computational Fluid Dynamics (CFD) codes coupled with Computational Structural Mechanics (CSM) ones requires accurate data transfer between the corresponding grid and mesh. The transformation method should be flexible to rapidly model complex interface geometries. Studies have shown that this could be accomplished by a finite-element-like approach.

Also pursuing reseach in:
Automatic mesh generation and graphical user interface for finite-element models; low-cost structural concepts for General Aviation applications; manufacturing cost
models for composite structures and their role in the structural design.