Investigation of design and analyses principles of honeycomb structures

Download
2007
Aydıncak, İlke
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.

Suggestions

Design, analysis and optimization of thin walled semi-monocoque wing structures using different structural idealizations in the preliminary design phase
Dababneh, Odeh; Kayran, Altan; Department of Aerospace Engineering (2011)
This thesis gives a comprehensive study on the effect of using different structural idealizations on the design, analysis and optimization of thin walled semi-monocoque wing structures in the preliminary design phase. In the design part, wing structures are designed by employing two different structural idealizations that are typically used in the preliminary design phase. In the structural analysis part, finite element analysis of one of the designed wing configurations is performed using six different one...
NUMERICAL-SIMULATION OF 3-DIMENSIONAL SUPERSONIC FREE SHEAR LAYERS
Tuncer, İsmail Hakkı (American Institute of Aeronautics and Astronautics (AIAA), 1992-04-01)
The temporal stability and growth characteristics of three-dimensional supersonic shear layers are numerically investigated. An explicit time-marching scheme that is second-order accurate in time and fourth-order accurate in space is used to study this problem. The shear layer is excited by instability waves computed from a linear stability analysis and random initial disturbances. At low convective Mach numbers, organized vortical structures develop both for the random disturbance and the modal disturba...
Attitude estimation and magnetometer calibration using reconfigurable TRIAD plus filtering approach
Söken, Halil Ersin (Elsevier BV, 2020-04-01)
This paper proposes using TRIAD and Unscented Kalman Filter (UKF) algorithms in a sequential architecture as a part of a small satellite attitude estimation algorithm. This TRIAD+UKF approach can both provide accurate attitude estimates for the satellite and calibrate the magnetometers in real-time. A complete calibration model for the magnetometers, considering bias, scale factor, soft iron and nonorthogonality errors, is assumed. In the algorithm's first stage, the TRIAD uses the available vector measurem...
Theoretical investigation of charge accumulation layer on the Bi-induced InAs(111)-(2 x 2) surface
Ozkaya, S.; Usanmaz, D.; ÇAKMAK, MELEK; Alkan, B.; Ellialtıoğlu, Süleyman Şinasi (AIP Publishing, 2014-04-28)
Based on pseudopotential method and density functional theory, we have investigated the stability, atomic geometry, and detailed electronic structures for Bi adsorbates on the InAs(111)-(2 x 2) surface with three different sites: (i) T-4 (Bi trimer centered on T-4 site), (ii) H-3 (Bi trimer centered on H-3 site), and (iii) T-4-H-3 (which is formed by trimers with opposite orientations: one centered on a T-4 site and the other on a H-3). Our total energy calculations suggest that adsorption on the T-4-H-3 si...
FREE-VIBRATION ANALYSIS OF LAMINATED COMPOSITE TRUNCATED CIRCULAR CONICAL SHELLS
Kayran, Altan (1990-07-01)
An analysis is presented for the free vibration characteristics of isotropic and laminated composite truncated circular conical shells including transverse shear deformation. All components of translatory and rotatory inertia are included. The applicability of linear shell theory due to Reissner is assumed, and governing equations are solved for the natural frequencies and mode shapes by using a combination of modal iteration and transfer matrix approach for different boundary conditions. Natural frequencie...
Citation Formats
İ. Aydıncak, “Investigation of design and analyses principles of honeycomb structures,” M.S. - Master of Science, Middle East Technical University, 2007.