Generation and Validation of Crack Growth Resistance Curve from DCB Specimens: An Experimental Study

Franklin, V. Alfred; Christopher, T.

doi:10.1007/s11223-013-9503-9

Cited by 9 publications

(3 citation statements)

References 20 publications

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“…Fracture toughness ( ) of the materials and estimates of the critical load for the DCB specimens are presented. The critical load at the onset of delamination from the critical strain energy release rate is compared with the fracture data of the materials in Figures 4,5,6,7,8,9,10,11,12,13,14,15,16,17,and 18. The critical load estimates at the onset of delamination are found to be in good agreement with existing test results.…”

Section: Critical Load ( Cr ) Estimates Of Dcb Specimenssupporting

confidence: 69%

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Influence of Root Rotation on Delamination Fracture Toughness of Composites

Franklin¹,

Christopher²,

Rao

2014

International Journal of Aerospace Engineering

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Large deviations have been observed while analysing composite double cantilever beam (DCB) specimens assuming each cracked half as a simple cantilever beam. This paper examines the effect of rotational spring stiffness(K)on the critical fracture energy(GIC)considering nonzero slope at the crack-tip of the DCB specimen by modelling each cracked half as the spring-hinged cantilever beam. The critical load estimates of DCB specimens fromGICare found to be in good agreement with in-house and existing test results of different composite material systems.

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Section: Critical Load ( Cr ) Estimates Of Dcb Specimenssupporting

confidence: 69%

“…The DCB specimens of 130 mm length, 20 mm width, and 3 mm thickness are made from carbon/epoxy and 3.25 mm thick carbon/PEEK composites. Fracture toughness tests are valid only when the initial delamination length ( 0 ) and the thickness (2ℎ) of DCB specimens satisfy the following criteria [14]:…”

Section: Experimentationmentioning

confidence: 99%

Influence of Root Rotation on Delamination Fracture Toughness of Composites

Franklin¹,

Christopher²,

Rao

2014

International Journal of Aerospace Engineering

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“…In fact, (6) predicts that the critical load does not depend on the crack length and thus remains constant throughout propagation. From this study, it is concluded that the R-curve effect noticed in 4ENF specimens was very mild as compared to mode I fracture test [36][37][38]. …”

Section: Resultsmentioning

confidence: 99%

Generation of R-Curve from 4ENF Specimens: An Experimental Study

Franklin¹,

Christopher²

2014

Journal of Composites

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The experimental determination of the resistance to delamination is very important in aerospace applications as composite materials have superior properties only in the fiber direction. To measure the interlaminar fracture toughness of composite materials, different kinds of specimens and experimental methods are available. This article examines the fracture energy of four-point end-notched flexure (4ENF) composite specimens made of carbon/epoxy and glass/epoxy. Experiments were conducted on these laminates and the mode II fracture energy, II , was evaluated using compliance method and was compared with beam theory solution. The crack growth resistance curve (R-curve) for these specimens was generated and the found glass/epoxy shows higher toughness values than carbon/epoxy composite. From this study, it was observed that R-curve effect in 4ENF specimens is quite mild, which means that the measured delamination toughness, II , is more accurate.

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Interlaminar Fracture Toughness Estimation of Aerospace Composites by Weighted Residual Approach

Franklin¹,

Christopher²

2015

Strength Mater

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Introduction. Preventing failure of composite material systems has been an important issue in engineering design. There are two types of physical failures that occur in laminated composite structures and interact in complex manner are intralaminar and interlaminar failures. Intralaminar failure is manifest in micromechanical components of the lamina such as fiber breakage, matrix cracking, and debonding of the fiber-matrix interface. Generally, aircraft structures made of fiber reinforces composite materials are designed such that the fibers carry the bulk of the applied load. Interlaminar failure such as delamination refers to debonding of adjacent lamina. The possibility that intralaminar and interlaminar failure occur in structural components is considered a design limit, and establishes restrictions on the usage of full potential of composites. Due to the lack of through-the-thickness reinforcement, structures made from laminated composite materials and adhesively bonded joints are highly susceptible to failure caused by interfacial crack initiation and growth. The delamination phenomenon in a laminated composite structure may reduce the structural stiffness and strength, redistribute the load in a way that the structural failure is delayed, or may lead to structural collapse. Therefore, delamination is not necessarily the ultimate structural failure, but rather it is the part of the failure process which may ultimately lead to loss of structural integrity.Most of the components on the aircraft are increasingly being replaced with composite materials. The main attraction is the effective reduction in mass with a comparative increase in stiffness, strength, fatigue and impact resistance, thermal conductivity and corrosion resistance. Through these replacements, the structural weight can be reduced, which will in turn lead to a more economical commercial aircraft [1]. The major structural applications for fiber-reinforced composites are in the field of military and commercial aircrafts, for which weight reduction is critical for higher speeds and increased payloads. Ever since the production application of boron fiber-reinforced epoxy skins for F-14 horizontal stabilizers, the use of fiber-reinforced polymers has experienced a steady growth in the aircraft industry. Carbon fiber-reinforced epoxy has become the primary material in many wings, fuselage, and empennage components. The structural integrity and durability of these early components have built up confidence in their performance and prompted developments of other structural aircraft components, resulting in an increasing amount of composites being used in military aircrafts. The F-22 fighter aircraft also contains nearly 25% by weight of carbon fiber-reinforced polymers. The outer skin of B-2 and other stealth aircrafts is almost all made of carbon fiber-reinforced polymers. The stealth characteristics of these aircrafts are due to the use of carbon fibers, special coatings, and other design features that reduce radar reflection and heat radiation [2].A...

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Generation and Validation of Crack Growth Resistance Curve from DCB Specimens: An Experimental Study

Cited by 9 publications

References 20 publications

Influence of Root Rotation on Delamination Fracture Toughness of Composites

Influence of Root Rotation on Delamination Fracture Toughness of Composites

Generation of R-Curve from 4ENF Specimens: An Experimental Study

Interlaminar Fracture Toughness Estimation of Aerospace Composites by Weighted Residual Approach

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