Determination of minimum doubler length for tapered sandwich structures

Download

index.pdf

Date

2019

Author

Altun, Aslıhan

Metadata

Show full item record

This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Item Usage Stats

200
views

85
downloads

Sandwich structures are widely used in aerospace industry due to their structural efficiency. In order to connect the sandwich structures to the adjacent parts, monolithic region is necessary. Because of the design requirements and strength necessities, this monolithic region must be strengthened. This reinforcement is provided by doublers [26]. In order to retain the weight advantage of sandwich structures, doubler span length must be minimum that keeps the core flatwise tension stress below the core allowable. In this thesis sandwich structures with different materials and different geometries under bending load are analyzed and the geometry of the doubler is designated such that minimum weight of the sandwich structure is obtained. ABAQUS Standard solver is used for the analyses. In the first part of the study after the determination of the mesh size, the effects of the friction coefficient between the parts in contact and the value of tightening torque of the bolts that connects the sandwich structure to adjacent parts are investigated. The effects of geometric and material nonlinearity are also examined in this part. Second part of the thesis covers the finite element model verification done by using tests and analytical approaches. At the final phase of the thesis, failure types of the sandwich structures are investigated and minimum failure load among these failure criteria is determined. The effect of doubler geometry on the failure mechanism is studied for several sandwich structures with specified geometry and materials. Doubler geometry is specified by doing a parametric study. This parametric study is performed by running Python scripts in ABAQUS Standard.

Subject Keywords

Sandwich construction., Keywords: Sandwich Structures, Tapered Sandwich Structures, Honeycomb, Finite Element Analysis, Sandwich Panel Local Reinforcements.

URI

http://etd.lib.metu.edu.tr/upload/12624366/index.pdf
https://hdl.handle.net/11511/44670

Collections

Graduate School of Natural and Applied Sciences, Thesis

Suggestions

OpenMETU
Core

Development of an equivalent model of aluminum honeycomb sandwich structures subjected to transverse loads Yardımcı, Oza; Gürses, Ercan; Department of Aerospace Engineering (2019) Sandwich structures are commonly employed in aviation because of the weight and strength advantages they provided. This common application has turned the accurate finite element analyses of them into a critical issue. In this thesis, a genetic algorithm-based optimization method is employed for creating accurate two-dimensional layered shell models of the sandwich panels with honeycomb cores. Firstly, the sandwich panels subjected to transverse loads with hexagonal honeycomb cores having different face shee...
EVALUATION OF TRANSVERSE SHEAR MODULI OF COMPOSITE SANDWICH BEAMS THROUGH THREE-POINT BENDING TESTS Şener, Özgün; ATALAY, OĞUZ; ATASOY, MERT; Kayran, Altan (2018-11-15) Transverse shear moduli of the sandwich core and flexural stiffness of all-composite sandwich constructions are determined with three-point beam bending tests, and compared with the analytical and finite element analysis solutions. Additionally, Digital Image Correlation (DIC) system is employed to validate the experimental results by monitoring the displacements. The effect of orientation of the composite core material with respect to the beam axis on the shear modulus of the core material itself, flexural...
Investigation of wear behavior of aged and non-aged SiC-reinforced AlSi7Mg2 metal matrix composites in dry sliding conditions ÇELİK, YAHYA HIŞMAN; Demir, Mehmet Emin; KILIÇKAP, EROL; Kalkanlı, Ali (Springer Science and Business Media LLC, 2020-01-01) Metal matrix composites (MMCs) with their splendid mechanical properties have been specifically designed for use in fields such as aerospace and aviation. The presence of hard ceramic particles in MMC increases the hardness of the matrix product and decreases its coefficient of friction. Therefore, the wear resistance is improved. Moreover, the mechanical properties of these composite materials can be improved by applying heat treatments. In this study, AlSi7Mg2 MMCs with 15 wt% SiC reinforcement were produ...
Determination of cracking related properties of engineering cementitious composites Keskin, Süleyman Bahadır; Şahmaran, Mustafa; Yaman, İsmail Özgür (null; 2017-09-12) Engineered Cementitious Composites (ECC) are relatively new types of fiber reinforced cementitious materials with enhanced mechanical properties such as tensile strain hardening accompanying high tensile strain capacity. This is mainly attributed to close and multiple cracks with widths remaining under 60 µm which contributes to durability of ECC material. These properties are only achievable as a result of a micro-mechanical design that requires special ingredients that make ECC costly to be used alone, ho...
Design optimization of truss structures using genetic algorithms Ünalmış, Dilek; Kayran, Altan; Department of Aerospace Engineering (2012) Design optimization of truss structures is a popular topic in aerospace, mechanical, civil, and structural engineering due to benefits to industry. Common design problem for the structures is the weight minimization. Especially in aerospace engineering the minimization of the weight of the total structure gets the highest importance in the design. This study focuses on the design optimization of 2D and 3D truss structures. The objective function is the total mass of the structure which is subjected to stres...

Citation Formats

A. Altun, “Determination of minimum doubler length for tapered sandwich structures,” Thesis (M.S.) -- Graduate School of Natural and Applied Sciences. Aerospace Engineering., Middle East Technical University, 2019.