Analysis of aircraft structures are mainly performed by assuming that the structure behaves
linearly. In linear finite element analysis, it is assumed that deformations are small, thus
geometric nonlinearity can be neglected. In addition, linear analysis assumes that linear constitutive
laws applicable, implying that material nonlinearity can also be neglected. One very
common type of nonlinearity is associated with the boundary conditions. Contact between
two deformable bodies or between a deformable and rigid body are typical examples of nonlinearity
associated with boundary conditions. Linear structural analysis, in general, does
not include contact analysis. Simplicity of linear analysis in terms modeling, interpreting the
results and solution time makes the linear analysis approach very convenient in preliminary
design and analysis stage of aircraft structures. However, simplicity of linear analysis may
result in unconservative results which may occur due to neglecting the true nonlinear behavior
of the structure. In this thesis, one such nonlinear eect called prying load eect on the
tensile connections is studied. The eect of prying load on structures are initially described
by referencing the analytical approaches presented in the literature. Finite element models of
typical bolted connections such as L and T type are generated for various combinations of the
chosen design parameters such as bolt diameter, flange thickness, washer diameter and edge
distances. Parametric modeling approach is used to perform the high number of finite element analysis which involve contact for the purpose of calculating the prying load. Comparative
study of the eect of prying load is then conducted by also including the results presented
in the literature. Comparisons of the prying load are done with the experimental results presented
in the literature. Series of finite element analyses are preformed for various cases such
that eect of geometrical variables and bolt preload on prying ratio can be understood. According
to the results obtained, it is concluded that main factors eecting the prying ratio are
the distance of bolt center to the clip web, flange thickness of the clip and preload on the bolt
where the eect of edge distance of the bolt is insignificant.
| Identifer | oai:union.ndltd.org:METU/oai:etd.lib.metu.edu.tr:http://etd.lib.metu.edu.tr/upload/12614163/index.pdf |
| Date | 01 February 2012 |
| Creators | Atasoy, Mert |
| Contributors | Kayran, Altan |
| Publisher | METU |
| Source Sets | Middle East Technical Univ. |
| Language | English |
| Detected Language | English |
| Type | M.S. Thesis |
| Format | text/pdf |
| Rights | Access forbidden for 1 year |
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