An Analytical and Experimental Investigation of Edge Delamination in Composite Laminates

Rodini, Benjamin; Eisenmann, J. R.

doi:10.1007/978-1-4684-1033-4_25

Cited by 37 publications

(19 citation statements)

References 8 publications

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“…In conclusion, these authors have attributed the problem of strength degradation to interlaminar stress effects. Similar conclusions were reported by Rodini and Eisenmann [7]. 7 Camponeschi [5], on the other hand, has presented compression data, which indicate strength degradation in sub laminate level scaled laminates.…”

Section: Introductionsupporting

confidence: 84%

“…Delamination stress versus n for a quasi-isotropic lay-up (±45°rJO°r/900n)s' A comparison between theory by [7], experiment by [7], and Eq.3 by [8].…”

Section: List Of Tablesmentioning

confidence: 99%

“…Previous research, [1][2][3][4][5][6][7], has shown that the strength and stiffness of fiber reinforced composite materials depend upon the size of the composite laminates. It has been demonstrated that the degree of influence depends upon the type of scaling level used, the stacking sequence, and the mode of loading.…”

Section: Introductionmentioning

confidence: 99%

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Strength scaling in fiber composites

Kellas

Morton

1991

32nd Structures, Structural Dynamics, and Materials Conference

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A research program has been initiated to study and isolate the factors responsible for scale effects in the tensile strength of graphite/epoxy composite laminates.Four lay-ups, (±30° n/9002n)s, (±45° n/O° n/90° n)s, (90° nlO° n/90° n/O° n)s, and (±45° n/±45 ° n)s, have been chosen with appropriate stacking sequences so as to highlight individual and interacting failure modes. Four scale sizes have been selected for investigation including full scale size, 3/4, 2/4, and 1/4, with n equal to 4, 3,2, and 1, respectively. The full scale specimen size was 32 plies thick as compared to 24, 16, and 8 plies for the 3/4, 2/4, and 1/4 specimen sizes respectively.Results were obtained in the form of tensile strength, Stress/strain curves and damage development. Problems associated with strength degradation with increasing specimen size have been isolated and discussed. Inconsistencies associated with strain measurements have also been identified. Enhanced X-ray radiography was employed for damage evaluation, following step loading.It has been shown that fiber dominated lay-ups were less sensitive to scaling effects compared to the matrix dominated lay-ups. Further, it has been shown that fabrication induced damage was partly responsible for the observed behavior.Extrapolation to the full scale strength was attempted by means of three basic methods: a Weibull statistics based model, a fracture mechanics based model, and a combination model involving the previous two models in conjunction with a failure criterion. The predictive performance of each one of these models has been assessed and their applicability to the present problem has been discussed.

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Section: Introductionsupporting

confidence: 84%

“…Delamination stress versus n for a quasi-isotropic lay-up (±45°rJO°r/900n)s' A comparison between theory by [7], experiment by [7], and Eq.3 by [8].…”

Section: List Of Tablesmentioning

confidence: 99%

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Strength scaling in fiber composites

Kellas

Morton

1991

32nd Structures, Structural Dynamics, and Materials Conference

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“…Great attention has been given to the problem of free-edge delamination in laminates subjected to in-plane static and fatigue loadings [1][2][3][4], and many people have attempted to measure the fracture toughness with respect to delamination cracks [5][6][7][8][9]. Few attempts have been made, however, to measure the dynamic delamination fracture toughness.…”

mentioning

confidence: 99%

Dynamic Delamination Crack Propagation in a Graphite/Epoxy Laminate

Grady

Sun

1986

Composite Materials: Fatigue and Fracture

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Ballistic impact tests of [90/0]5s T-300/934 graphite/epoxy laminates of beam-like dimension with embedded delamination cracks were conducted. High speed photography (16 000 frames/second) was used to record the impact response and subsequent crack propagation. From the photographic data, impact characteristics such as the contact duration and the dynamic response of the impact specimen were measured. In addition, the time of initiation of delamination propagation and measurements of the subsequent delamination length versus time were obtained. By changing the location of the embedded delamination in the specimens relative to the impact point, additional results were obtained on the variation of the threshold impact velocity necessary to cause crack propagation in the different specimen configurations. These data, together with the photographic results, suggest that the mode of crack propagation is dependent on the specimen geometry as well as the loading condition. The time dependent nature of the crack velocity and its variation with impact conditions was investigated. A finite element program was used to calculate the dynamic strain energy release rate before the onset of crack propagation. This strain energy release rate was used to gage the instability of the delamination crack during impact.

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“…The thickness effect on crack initiation observed both in edge delamination and transverse cracking has been explained from a probabilistic point of view (13,171. In this view, it is assumed that in each material layer there is a distribution of microdefects and that a similar distribution of defects may also exist on the layer interfaces.…”

Section: And Hahn [L])mentioning

confidence: 99%