All flight vehicles are subject to aeroelastic effects and for many, their performance is limited by adverse aeroelastic interactions. Future aircraft design would benefit from a more comprehensive integration of both positive and negative aeroelastic effects (i.e., response of aircraft structure to aerodynamic loads). Computational simulation holds the promise of a more timely and cost effective method of investigating these phenomena than wind tunnel or flight testing. The challenge then becomes one of developing more accurate and robust computational models.

The CFD Research Branch of the Aeromechanics Division of AFRL currently maintains a code (FDL3DI) that addresses this challenge. It is based on a scheme that implicitly couples its fluids and structures solvers via Newton-like subiterations. In comparison to time-lagged strategies that solve the fluid and structural equations sequentially, this approach simultaneously yields higher order accuracy in time while reducing linearization and factorization error. The algorithmic framework represented by this code is sound, but the capabilities of the structural solver are limited to generalized displacement (modal) analyses, and so it is this specific area that has been targeted for improvement.

PROJECT OBJECTIVES

The objective of this project is to improve the FDL3DI structural capabilities by incorporating a 3D linear-elastic structural solver within the current framework. The structural solver will support the following element types: bar, triangular membrane, quadrilateral membrane, shear panel and shell including both membrane and bending behavior. The structural solver will have a direct solver based on Gaussian elimination, and an indirect solver based on the Conjugate Gradient Method.

DELIVERABLES

The deliverables for this project are a modular 3D linear-elastic structural solver and a collection of reusable visualization tools for examining data from multidisciplinary simulations.

CUSTOMERS

Customers include the following research scientists in the CFD Research Branch of the Aeromechanics Division of AFRL:

M. Visbal
R. Gordnier
R. Melville

Other end users will be scientist and researchers throughout government labs who require a modular and portable 3D structural solver for their programs. In addition, this solver can be used with PATRAN as a general purpose finite element code.

BENEFIT TO THE WARFIGHTER

This multidisciplinary project will help engineers design future aircraft with a more comprehensive understanding and consideration of aeroelastic interactions. This will improve the performance and survivability of aircraft and their pilots during combat. In addition, this software will help reduce prototyping (wind tunnel tests), thus reducing delivery time and cost for new aircraft development.

PROJECT DEPENDENCIES AND SCOPE This project depends on the collaboration of the CSM, CFD and Scientific Visualization community at ASC including:

D. O'Neal - CSM NCSA
D. Semeraro - Scientific Visualization NCSA
H. Thornburg - CFD MSU
M. Visbal, R. Gordnier, R. Melville - AFRL

RISK ELEMENT

The risk element of this project is relatively low. Defining software test methodology and analyzing the test results will require a substantial amount of time, and is critical for software certification.