Reliable flutter analysis of aircraft structures is a major requirement to determine
safe flight envelops. Dynamically equivalent finite element model of an aircraft
structure correlating well with experimental modal is a major requirement for a
reliable flutter analysis. Currently available model updating techniques require
enormous time and engineering work to achieve appropriate finite element models
of aircraft structures. The method developed within the scope of this thesis work
aims to remove important disadvantages of common model updating procedures. In
doing this, the method starts with a simple finite element mesh obtained by
connecting measurement points, used in the Ground Vibration Test of an aircraft
structure, with 3 D Euler-Bernoulli beam elements. Initial estimates of the geometric
and material properties are determined by solving structural identification equations
derived from the mass and stiffness orthogonality of experimental modes. By using
those initial estimates, an initial finite element model is constructed. Starting from
this initial finite element model, structural identification equations are updated and
solved iteratively by using experimental natural frequencies and eigenvectors of the
v
updated finite element model representing the same mode shapes with measured
normal modes. Iterations are continued until eigen solution of the updated finite
element model closely correlates with experimental modal data.
The applicability of the method is illustrated on a scaled aircraft model and a real
aircraft structure. The results are quite satisfactory but the method requires further
improvements to achieve a much better correlation level in case of real aircraft
structures.
| Identifer | oai:union.ndltd.org:METU/oai:etd.lib.metu.edu.tr:http://etd.lib.metu.edu.tr/upload/12612522/index.pdf |
| Date | 01 September 2010 |
| Creators | Karaagacli, Taylan |
| Contributors | Ozguven, Nevzat Hasan |
| Publisher | METU |
| Source Sets | Middle East Technical Univ. |
| Language | English |
| Detected Language | English |
| Type | M.S. Thesis |
| Format | text/pdf |
| Rights | To liberate the content for public access |
Page generated in 0.0019 seconds