INVESTIGATION OF INTERSONIC FRACTURE IN HIGLY CURVED COMPOSITE LAMINATES UNDER QUASI-STATIC LOADING

2014-07-25
Gozluklu, B.
Uyar, I
Çöker, Demirkan
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. This is a problem that has recently risen to the forefront in in-service new composite civil aircrafts. This study focuses on experimental and computational investigation of dynamic delamination in a 12-layered woven L-shaped CFRP laminates subjected to quasi-static shear loading. Delamination initiation and propagation processes were captured with a million fps high speed camera. A single delamination is found to initiate in the curved region at the 5th interface during a single drop in the load. The delamination is then observed to propagate at intersonic speed of 2200m/s. The experiments are simulated using cohesive elements by implementing bilinear cohesive model into ABAQUS/Explicit. The experiments and computations are found to be in good agreement, at the macroscale in terms of load-displacement behavior and the failure load, and at the mesoscale in terms of the location of delamination nucleation and delamination crack tip speeds. Shear Mach waves emanating from the crack tips are also observed in the simulations during intersonic crack propagation.

Suggestions

INVESTIGATION OF DAMAGE IN GFRP TAPERED COMPOSITE LAMINATES
Hosseinpour Dashatan, Saeid; Arıkan, Mehmet Ali Sahir; Parnas, Kemal Levend; Department of Mechanical Engineering (2021-8-13)
In some applications of composite laminates, thickness variation is necessary to fulfill specific design requirements. One way of accomplishing the intentional thickness variation in composite structures is terminating some plies within a layup. Introducing ply drop-offs causes geometrical and material discontinuities, which lead to high localized stresses around drop-off locations. Despite all the progress made in damage analyses of tapered composite laminates, estimating their load-carrying capacity and s...
Strengthening of L-shaped composite laminates using carbon nanotube reinforcement and thin ply non-crimp fabrics
Arca, Miray Aydan; Çöker, Demirkan; Papila, Melih; Department of Aerospace Engineering (2014)
The advances in manufacturing technologies have increased the use of composite materials in complex shapes such as curved beams. However, use of composites in complex geometries creates a weakness at the curvature and causes delamination failure. Major objective is to provide solution for this problem without degrading properties or increasing the weight of the structure. In this study, the effect of CNTs in the resin and the use of non-crimp fabric on the fracture toughness and curved beam strength of lami...
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...
USAGE OF FUZZY MULTI CRITERIA DECISION MAKING METHODS IN SELECTION OF NONTRADITIONAL MANUFACTURING METHODS
Kul, Yavuz; Seker, Alper; YURDAKUL, MUSTAFA (2014-01-01)
New manufacturing technologies such as nontraditional manufacturing methods (NMM) were needed recently because of new machining requirements for parts with complex geometries, very narrow machining area and high strength materials and also for very small and delicate parts. Since NMM are diverse and their numbers are increasing with the development of new approaches, selecting the most appropriate one among many NMM requires systematic models which incorporate multi-criteria decision making approaches. In t...
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...
Citation Formats
B. Gozluklu, I. Uyar, and D. Çöker, “INVESTIGATION OF INTERSONIC FRACTURE IN HIGLY CURVED COMPOSITE LAMINATES UNDER QUASI-STATIC LOADING,” 2014, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/54708.