Investigation of design and analyses principles of honeycomb structures

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Tezin Türü: Yüksek Lisans

Tezin Yürütüldüğü Kurum: Orta Doğu Teknik Üniversitesi, Mühendislik Fakültesi, Havacılık ve Uzay Mühendisliği Bölümü, Türkiye

Tezin Onay Tarihi: 2007

Öğrenci: İLKE AYDINCAK

Danışman: ALTAN KAYRAN

Özet:

In this thesis, design and analyses of honeycomb structures are investigated. Primary goal is to develop an equivalent orthotropic material model that is a good substitute for the actual honeycomb core. By replacing the actual honeycomb structure with the orthotropic model, during the finite element analyses, substantial advantages can be obtained with regard to ease of modeling and model modification, solution time and hardware resources . To figure out the best equivalent model among the approximate analytical models that can be found in the literature, a comparison is made. First sandwich beams with four different honeycomb cores are modeled in detail and these are accepted as reference models. Then a set of equivalent models with the same dimensions is generated. The material properties of the equivalent models are taken from different studies performed in the literature. Both models are analyzed under the same loading and the boundary conditions. In finite element analyses, ANSYS finite element program is used. The results are compared to find out the best performing equivalent model. After three major analyses loops, decision on the equivalent model is made. The differences between the total reaction forces calculated by the equivalent model and the actual honeycomb model are all found to be within 10%. The equivalent model gives stress results at the macro-scale, and the local stresses and the strains can not be determined. Therefore it is deemed that for stress analysis, equivalent model can be used during the preliminary design phase. However, the equivalent model can be used reliably for deflection analysis, modal analysis, stiffness determination and aero-elastic analysis.