Analytical prediction of the local Young’s modulus in CFRP laminate with ply discontinuity: a variational approach

Fikry, M. J. Mohammad; Vinogradov, Vladimir; Ogihara, Shinji

doi:10.1080/09243046.2023.2165873

Cited by 2 publications

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References 27 publications

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“…Figure 1 illustrates a tapered laminate in a composite structure; a resin-rich pocket is formed at the edge of the dropped ply when an internal ply is terminated. This discontinuity creates stress concentrations and serves as an onset point for damages (Nakatani et al, 2011(Nakatani et al, , 2013Fikry et al, 2022aFikry et al, , 2022bFikry et al, , 2023. All forms of internal ply joints, including tapered, overlapped, or butted joints, frequently develop cracks at the dropping ply edges.…”

Section: Introductionmentioning

confidence: 99%

Mechanical properties and damage behavior of tapered unidirectional CFRP laminates

Fikry

Vinogradov

Ogihara

2023

Mechanical Engineering Journal

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An understanding of damage mechanisms induced by drop-off plies in tapered composite laminates is crucial. This study investigated the mechanical properties and damage behaviors of asymmetric tapered unidirectional carbon fiber-reinforced plastic laminates. Damage observations of laminates with simultaneous tapered and staggered tapered structures under monotonic and cyclic tensile loads were done by an optical microscope and X-ray radiography. Based on the results, matrix cracks in the resin pocket and delamination occurred earliest in the simultaneous tapered specimen due to a greater stress concentration in a single large resin pocket in the structure. Intralaminar damages in the staggered tapered specimen with a shorter step spacing occurred mainly in the lower dropped ply as there was a more significant interaction between the neighboring steps in the specimen. The drastic decrease in the stress concentration after the occurrence of damages in the neighboring step(s) then suppressed the occurrence of intralaminar damages in the upper dropped ply. This is in contrast to the specimen with a longer step spacing where the intralaminar damages occurred in both dropped plies due to the distributed stress distribution. Delamination propagated between the dropped plies and continuous (belt and core) plies for both staggered laminates regardless of the length of the step spacing at higher applied stress levels. The results showed that internal ply-drop configuration and step spacing in staggered tapered structures contribute to significant differences in the mechanical properties and damage behavior in the laminates.

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Section: Introductionmentioning

confidence: 99%

Mechanical properties and damage behavior of tapered unidirectional CFRP laminates

Fikry

Vinogradov

Ogihara

2023

Mechanical Engineering Journal

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Ply Refinement Technique を用いた負荷方向に材料特性が異なる領域を有する積層板の変分応力解析の拡張

FIKRY,

VINOGRADOV,

OGIHARA

2024

J. Soc. Comp. Mat.

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This work extends the applicability of a recent variational model that has been used for analyzing laminates to determine the stress state in a laminate with alternating material properties in the longitudinal direction subject to tensile and bending loading. For simplicity, a plane stress problem was assumed in this study. The laminate was subdivided in the longitudinal (tensile loading) direction as in the previous analysis. In addition, the laminate was subdivided in the thickness direction by using the ply refinement technique. To introduce the ply refinement technique and to account for continuity boundary conditions between divided regions in the loading direction, the Lagrange multiplier strategy was used. Closed form expressions for the energy function derived from using the strategy led to a very concise solution for determining the approximate stresses in the laminates. As an example, a laminate with ply discontinuity was analyzed, and the resultant stress distributions were then compared to the previous variational analysis model and finite element method (FEM). Compared to the previous analysis, stress concentration at the region interfaces could be captured, and excellent agreement between FEM was demonstrated.

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Analytical prediction of the local Young’s modulus in CFRP laminate with ply discontinuity: a variational approach

Cited by 2 publications

References 27 publications

Mechanical properties and damage behavior of tapered unidirectional CFRP laminates

Mechanical properties and damage behavior of tapered unidirectional CFRP laminates

Ply Refinement Technique を用いた負荷方向に材料特性が異なる領域を有する積層板の変分応力解析の拡張

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