Experimental investigation on deformation and strength of carbon/epoxy laminated curved beams

Hao, Wenfeng; Ge, Dongyun; Ma, Yinji; Yao, Xuefeng; Shi, Yuejiang

doi:10.1016/j.polymertesting.2012.02.003

Cited by 108 publications

(47 citation statements)

References 16 publications

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“…28,29 Only one paper was found where a clear difference in radial stress for samples with different thickness was found. 30 It is difficult to directly compare the results since no results for the same material, or any other CFRP thermoplastic for that matter, were found. Using a thermoplastic matrix and short carbon fibres, a maximum radial stress of 21M P a was found for a thickness of 2mm and a radius of 3 or 5mm.…”

Section: Characterization Testsmentioning

confidence: 99%

See 1 more Smart Citation

Thermoplastic Composite Stiffener Design with Manufacturing Considerations

Peeters

Clancy

Oliveri

et al. 2018

2018 AIAA/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference

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Fiber reinforced composite materials are finding increasing application in aerospace structures due to their superior specific properties. Aerospace structures make widespread use of stiffening elements, such as stringers, for example in the wingbox or the fuselage. Sizing of stiffeners to fulfill strength, stiffness and manufacturing considerations is a significant challenge for aircraft designers. This paper proposes a novel manufacturing approach using winding and laser-assisted tape placement (LATP) to manufacture an omega-shaped stiffener. The stiffener design is used as the stiffening elements in a wingbox; the sizing of the stringer is based on the optimized buckling response of the wingbox, with manufacturing constraints also taken into consideration. The stringer is manufactured by LATP winding over a novel collapsible tool. The tool utilizes a low-melt alloy as a spacer, which can be removed post-process by exposing the mold to the alloy melt temperature, which is below the glass transition temperature of the thermoplastic composite material. Manufacturing tests have shown that using the new mold design leads to repeatable stiffeners of the correct dimensions. Characterisation tests have shown that the strength of the corners has to be checked in future work. The bond strength of the stiffeners is satisfactory.

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Section: Characterization Testsmentioning

confidence: 99%

“…The only study that finds a significantly lower radial stress is done for thick laminates: 20, 40 and 60 plies are used, with a radius to thickness ratio of 0.8, 1 and 1.5. 30 The maximal radial stress is 7 − 8M P a for the thinnest material and only 4 − 5M P a for the thickest laminate. However, this could be due to the increasing radius as well.…”

mentioning

confidence: 97%

Thermoplastic Composite Stiffener Design with Manufacturing Considerations

Peeters

Clancy

Oliveri

et al. 2018

2018 AIAA/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference

View full text Add to dashboard Cite

show abstract

“…Wimmer et al [6] studied the failure initiation and propagation in L-shaped laminates experimentally and numerically. Hao et al [7] conducted experiments to investigate delamination in different laminates. Michel et al [8] analyzed curved laminates in four-point bending tests.…”

Section: Introductionmentioning

confidence: 99%

Investigation of failure initiation in curved composite laminates using a higher-order beam model

Thurnherr

Groh

Ermanni

2017

Composite Structures

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General rightsThis document is made available in accordance with publisher policies. Please cite only the published version using the reference above. AbstractCurved laminates are prone to delamination failure from applied bending moments that straighten out the laminate and induce tensile stresses in the unreinforced radial direction. These non-classical through-thickness stresses are important even for thinner configurations and need to be accounted for in the design of lightweight composite structures, preferably in a computationally efficient manner. Here, we investigate failure-inducing critical stresses for a number of curved laminates using a higher-order beam model derived from the Hellinger-Reissner mixed variational principle, which guarantees that the hoop, interlaminar shear and radial stresses are equilibrated. By solving the governing equations of the theory in the strong form using the pseudo-spectral differential quadrature method, the model is capable of predicting accurate 3D stress fields in curved laminates, even in the vicinity of loacalised features such as supported edges. The model is used alongside commonly used failure criteria to reproduce experimental failure initiation results found in the literature, and the comparison suggests that failure mode, location and load are all predicted accurately. Finally, failure maps that highlight the critical stress component for failure initiation are constructed. As the thickness of the curved laminate increases, the critical stress component transitions from intralaminar hoop stress to interlaminar shear or radial stress depending on the specific laminate configuration. These findings and failure maps collectively provide insights into the mechanics of failure initiation that should also prove useful for design purposes.

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“…GonzalezCantero et al [12] proposed a semi-analytical method to calculate interlaminar stresses in curved beams with constant curvature. Other authors conducted experiments to verify the real behavior of curved laminates [10,13], but these tests cannot serve as a general strategy to predict delamination failure.…”

Section: Introductionmentioning

confidence: 99%

Higher-order beam model for stress predictions in curved beams made from anisotropic materials

Thurnherr

Groh

Ermanni

2016

International Journal of Solids and Structures

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A higher-order beam model for analyzing the flexural response of curved multilayered beams with constant curvature and arbitrary constant thickness is developed. The new model is derived from the Hellinger-Reissner mixed variational statement and predicts inherently equilibrated 3D stresses from an equivalent single-layer model. As a starting assumption, the hoop stress is formulated as a series of higher-order stress resultants multiplied by Legendre polynomials. The governing equations are derived in a generalized manner such that the modeling order can be adjusted and is not defined a priori. Hence, the highest order Legendre polynomial determines the modeling order. The through-thickness shear and normal stresses are derived by integrating the generalized hoop stress in Cauchy's polar equilibrium equations. As a result, all stress fields are based on the same set of variables, thereby considerably reducing the computational effort. The three stress fields, and two displacements in the radial and hoop directions are used in the Hellinger-Reissner functional to derive a new set of stress-displacement relations. The enforcement of the classical membrane and bending equilibrium equations of curved beams in the Hellinger-Reissner functional guarantees that all interlaminar and surface traction equilibrium conditions are satisfied exactly. A validation study of a composite laminate using a high-fidelity 3D finite element model shows that the stresses are captured very accurately by the present model, but with much less computational effort than the finite element model. As a result, the developed model can provide rapid and accurate insights into the expected damage onset behavior of curved laminates.

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Experimental investigation on deformation and strength of carbon/epoxy laminated curved beams

Cited by 108 publications

References 16 publications

Thermoplastic Composite Stiffener Design with Manufacturing Considerations

Thermoplastic Composite Stiffener Design with Manufacturing Considerations

Investigation of failure initiation in curved composite laminates using a higher-order beam model

Higher-order beam model for stress predictions in curved beams made from anisotropic materials

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