Structural optimization strategies via different optimization and solver codes and aerospace applications

Ekren, Mustafa
In this thesis, structural optimization study is performed by using three different methods. In the first method, optimization is performed using MSC.NASTRAN Optimization Module, a commercial structural analysis program. In the second method, optimization is performed using the optimization code prepared in MATLAB and MSC.NASTRAN as the solver. As the third method, optimization is performed by using the optimization code prepared in MATLAB and analytical equations as the solver. All three methods provide certain advantages in the solution of optimization problems. Therefore, within the context of the thesis these methods are demonstrated and the interface codes specific to the programs used in this thesis are explained in detail. In order to compare the results obtained by the methods, the verification study has been performed on a cantilever beam with rectangular cross-section. In the verification study, the height and width of the cross-section of the beam are taken as the two design parameters. This way it has been possible to show the design space on the two dimensional graph, and it becomes easier to trace the progress of the optimization methods during each step. In the last section structural optimization of a multi-element wing torque box has been performed by the MSC.NASTRAN optimization module. In this section geometric property optimization has been performed for constant tip loading and variable loading along the wing span. In addition, within the context of shape optimization optimum rib placement problem has also been solved.


Semi analytical study of stress and deformation analysis of anisotropic shells of revolution including first order transverse shear deformation
Oygür, Özgür Sinan; Kayran, Altan; Department of Aerospace Engineering (2008)
In this study, anisotropic shells of revolution subject to symmetric and unsymmetrical static loads are analysed. In derivation of governing equations to be used in the solution, first order transverse shear effects are included in the formulation. The governing equations can be listed as kinematic equations, constitutive equations, and equations of motion. The equations of motion are derived from Hamilton’s principle, the constitutive equations are developed under the assumptions of the classical laminatio...
Nonlinear flutter calculations using finite elements in a direct Eulerian-Lagrangian formulation
Seber, Guclu; Bendiksen, Oddvar O. (American Institute of Aeronautics and Astronautics (AIAA), 2008-06-01)
A fully nonlinear aeroelastic formulation of the direct Eulerian-Lagrangian computational scheme is presented in which both structural and aerodynamic nonlinearities are treated without approximations. The method is direct in the sense that the calculations are done at the finite element level, both in the fluid and structural domains, and the fluid-structure system is time-marched as a single dynamic system using a multistage Runge-Kutta scheme. The exact nonlinear boundary condition at the fluid-structure...
Forced Response Prediction of Constrained and Unconstrained Structures Coupled Through Frictional Contacts
Ciğeroğlu, Ender; Menq, Chia-Hsiang (ASME International, 2009-03-01)
In this paper, a forced response prediction method for the analysis of constrained and unconstrained structures coupled through frictional contacts is presented. This type of frictional contact problem arises in vibration damping of turbine blades, in which dampers and blades constitute the unconstrained and constrained structures, respectively. The model of the unconstrained/free structure includes six rigid body modes and several elastic modes, the number of which depends on the excitation frequency. In o...
Development of de-icing and anti-icing solutions for aircraft on ground and analysis of their flow instability characteristics
Körpe, Durmuş Sinan; Özgen, Serkan; Department of Aerospace Engineering (2008)
In this thesis, development process of de-icing and anti-icing solutions and their flow instability characteristics are presented. In the beginning, the chemical additives in the solutions and their effects on the most critical physical properties of the solutions were investigated. Firstly, chemical additives were added to glycol and water mixtures at different weight ratios one by one in order to see their individual effects. Then, the changes in physical properties were observed when the chemicals were a...
Assessment of an iterative approach for solution of frequency domain linearized euler equations for noise propagation through turbofan jet flows
Dizemen, İlke Evrim; Yörükoğlu, Yusuf; Department of Aerospace Engineering (2007)
This study, explores the use of an iterative solution approach for the linearized Euler equations formulated in the frequency domain for fan tone noise propagation and radiation through bypass jets. The aim is to be able to simulate high frequency propagation and radiation phenomena with this code, without excessive computational resources. All computations are performed in parallel using MPI library routines on a computer cluster. The linearized Euler equations support the Kelvin-Helmholtz type convective ...
Citation Formats
M. Ekren, “Structural optimization strategies via different optimization and solver codes and aerospace applications,” M.S. - Master of Science, Middle East Technical University, 2008.