Effect of dropped plies on the strength of graphite-epoxy laminates

Curry, James M.; Johnson, Eric R.; Starnes, James H.

doi:10.2514/6.1987-874

Cited by 18 publications

(9 citation statements)

References 1 publication

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“…The two last options lead to abrupt changes in the thickness direction, which produce stress concentration and out-of-plane, interlaminar, stresses. 86,88 Moreover, unlike stiffeners, curvilinear fibres do not introduce major geometry variations. Curved fibres offer a wider degree of possibilities than variations of rectilinear fibre volume fraction and provide a solution to the problem of continuity when one considers manufacturing a structure with different fibre angles in adjoining elements.…”

Section: Introductionmentioning

confidence: 99%

A review on the mechanical behaviour of curvilinear fibre composite laminated panels

Ribeiro

Akhavan

Teter

et al. 2013

Journal of Composite Materials

161

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A review on works that investigate the mechanical behaviour of variable stiffness composite laminated panels is carried out in this paper. The review mostly focuses on buckling, failure and vibrations in laminates reinforced by curvilinear fibres, although other issues related to variable stiffness laminates are also addressed. The peculiarities in the formulation of curvilinear fibre reinforced plates are briefly described. As an illustration, the natural frequencies of vibration of variable stiffness composite laminated plates with curvilinear fibres are computed by an h-version type finite element code and are compared with the ones calculated using another model, based on a Third-order Shear Deformation Theory. Areas of research to explore on variable stiffness composite laminates are suggested.

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Section: Introductionmentioning

confidence: 99%

A review on the mechanical behaviour of curvilinear fibre composite laminated panels

Ribeiro

Akhavan

Teter

et al. 2013

Journal of Composite Materials

161

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“…Ply drop-off in laminated composites has been identified as a stress riser from the very beginning [1,7]. Since the last decade several experimental and analytical studies have been reported regarding various aspects of this problem.…”

Section: Introductionmentioning

confidence: 99%

Design guidelines for ply drop-off in laminated composite structures

Mukherjee

Varughese

2001

Composites Part B: Engineering

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“…In order to design damage resistant tapered structures, many parameters affecting delamination at dropped plies, such as the taper geometry and location of the ply-drops through the thickness must be considered [6,7]. Several studies have considered delamination failure in tapered laminates with internal ply drops under pure tension loads [1][2][3][4][5][6][7][8][9][10][11][12]. References 1-3, 6, 8, and 9 used finite element (bE) modeling and stress-based failure criteria to predict the strength of tapered laminates of a variety of different materials and with different internal ply-drop configurations.…”

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confidence: 99%

Fatigue Life Methodology for Tapered Composite Flexbeam Laminates

Murri¹,

O’Brien²,

Rousseau³

1998

J. Am. Helicopter Society

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The viability of a method for determining the fatigue life of composite rotor hub flexbeam laminates using delaminafion fatigue characterization data and a geometric non-linear finite element (FE) analysis was studied. Combined tension and bending loading was applied to non-linear tapered flexbeam laminates with internal ply drops. These laminates, consisting of coupon specimens cut from a full-size S2/E7T1 glass-epoxy flexbeam were tested in a hydraulic load frame under combined axialtension and transverse cyclic bending. The magnitude of the axial load remained constant and the direction of the load rotated with the specimen as the cyclic bending load was applied. The first delamination damage observed in the specimens occurred at the area around the tip of the outermost ply-drop group. Subsequently, unstable delamination occurred by complete delamination along the length of the specimen.Continued cycling resulted in multiple delaminations.A 2D finite element model of the flexbeam was developed and a geometrically non-linear analysis was performed.The global responses of the model and test specimens agreed very well in terms of the transverse displacement.The FE model was used to calculate strain energy release rates (G) for delaminations initiating at the tip of the outer ply-drop area and growing toward the thick or thin regions of the flexbeam, as was observed in the specimens. The delamination growth toward the thick region was primarily mode II, whereas delamination growth toward the thin region was almost completely mode I. Material characterization data from cyclic double-cantilevered beam tests was used with the peak calculated G values to generate a curve predicting fatigue failure by unstable delamination as a function of the number of loading cycles. The calculated fatigue lives compared well with the test data.

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Effect of dropped plies on the strength of graphite-epoxy laminates

Cited by 18 publications

References 1 publication

A review on the mechanical behaviour of curvilinear fibre composite laminated panels

A review on the mechanical behaviour of curvilinear fibre composite laminated panels

Design guidelines for ply drop-off in laminated composite structures

Fatigue Life Methodology for Tapered Composite Flexbeam Laminates

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