Experimental investigation of dynamic delamination in curved composite laminates

Download

index.pdf

Date

2014

Author

Uyar, İmren

Metadata

Show full item record

Item Usage Stats

191
views

100
downloads

In the aerospace industry, high demand for lightweight structures is fostering the use of composite laminates in a wide variety of shapes, as primary load carrying elements. However, once a composite laminate takes a highly curved shape, such as an L-shape, high interlaminar stresses induced in the curved region causes dynamic delamination formation. This thesis discusses the experimental investigation of delamination in L-shaped CFRP composite laminates under quasi-static shear loading. An experimental setup is designed to apply pure quasi-static shear loading. Three lay-up configurations are investigated: [0/90] fabric, uni-directional [0] and cross-ply [90/0] CFRP composite laminates. The effect of material lay-up, inner radius and thickness on the failure process is studied. The load displacement curves are recorded and the subsequent dynamic delamination is captured with a million fps high-speed camera. The failed specimens are analyzed under a microscope. A single delamination is found to grow in a single load drop for [0/90] fabric laminate. Multiple delaminations in a single load drop are observed in the failure of the unidirectional laminate whereas a sequential delamination at each discrete load drop is seen in the cross-ply laminate. The geometrical constraints such as the thickness and the inner radius are also found to be affecting the failure process. Delamination in all cases is observed to be propagating in the arms at the intersonic speed of 2200 m/s. This study presents the first known experimental evidence of intersonic delamination in composite laminates.

Subject Keywords

Composite materials., Fracture mechanics., Materials, Deformations (Mechanics).

URI

http://etd.lib.metu.edu.tr/upload/12618074/index.pdf
https://hdl.handle.net/11511/24093

Collections

Graduate School of Natural and Applied Sciences, Thesis

Suggestions

OpenMETU
Core

Dynamic failure of curved CFRP composite laminates under quasi static loading Çöker, Demirkan (null; 2015-04-15) In aerospace and wind energy industries, new advances in composite manufacturing technology and high demand for lightweight structures are fostering the use of composite laminates in a wide variety of shapes as primary load carrying elements. However, once a moderately thick laminate takes highly curved shape, such as an L-shape, Interlaminar Normal Stresses (ILNS) are induced together with typical Interlaminar Shear Stresses (ILSS) on the interfaces between the laminas. The development of ILNS promotes mod...
INVESTIGATION OF INTERSONIC FRACTURE IN HIGLY CURVED COMPOSITE LAMINATES UNDER QUASI-STATIC LOADING Gozluklu, B.; Uyar, I; Çöker, Demirkan (2014-07-25) In wind energy and aerospace industries, new advances in composite manufacturing technology enable to produce primary load carrying elements as composite materials in wide variety of shapes large such as an L-shape. However, due to the geometry, Interlaminar Normal Stresses (ILNS) are induced once a moderately thick laminate takes highly curved shape. In the curved part of the L-shaped structure, the development of ILNS promotes mode-I type of delamination propagation which is the weakest fracture mode. Thi...
Experimental investigation of CNT effect on curved beam strength and interlaminar fracture toughness of CFRP laminates Arca, M. A.; Çöker, Demirkan (2014-06-20) High mechanical properties and light weight structures of composite materials and advances in manufacturing processes have increased the use of composite materials in the aerospace and wind energy industries as a primary load carrying structures in complex shapes. However, use of composite materials in complex geometries such as L-shaped laminates creates weakness at the radius which causes delamination. Carbon nanotubes (CNTs) is preferred as a toughening materials in composite matrices due to their high m...
Structural lightweight concrete with natural perlite aggregate and perlite powder Aşık, Mesut; Turanlı, Lutfullah; Department of Civil Engineering (2006) Structural lightweight aggregate concrete is an important and versatile material, which offers a range of technical, economic and environmental-enhancing and preserving advantages and is designed to become a dominant material in the new millennium. For structural application of lightweight concrete, the density is often more important than the strength. A decreased density for the same strength level reduces the self-weight, foundation size and construction costs. Structural lightweight aggregate concrete g...
Modeling of intersonic delamination in curved and thick composite laminates under quasi-static loading Gözlüklü, Burak; Çöker, Demirkan; Department of Aerospace Engineering (2014) One of the widely used geometrically complex parts in advanced commercial aircraft is L-shaped composite laminates in which mixed-mode delamination failure is reported. Dynamic delamination under quasi-static loading is studied using explicit finite element method in conjunction with Cohesive Zone Modeling (CZM). A 4-noded interface element working with Bilinear (BL), Xu-Needleman (XN) and ratedependent bilinear (RD) CZMs are implemented in ABAQUS/Explicit. The interface elements are validated with benchmar...

Citation Formats

İ. Uyar, “Experimental investigation of dynamic delamination in curved composite laminates,” M.S. - Master of Science, Middle East Technical University, 2014.