Out-of-plane coupling effects on stress intensity factors at interface cracks in composite lap joints

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3 Citations (Scopus)

Abstract

The existence of off-axis plies in adhesively bonded lap joints leads to anisotropic stress-strain relationships where the in-plane and out-of-plane components of stress and deformation (in a plane perpendicular to the width of the joint) are coupled. In this paper, the anisotropic elasticity solution near a bimaterial crack tip is formulated using an eigenfunction expansion of the stresses and displacements. This elasticity solution is subsequently used in conjunction with finite elements in a global/local method in order to determine mode I, mode II, and mode III stress intensity factors. Numerical results for [(±Θ)2]s layups indicated that an out-of-plane mode III stress intensity factor, KIII, arises when off-axis plies are present even though the loading is in-plane. Depending on the layup angle and crack location, KIII can be as large as 43% of KI and 55% KII. It was also found that, in addition to producing a mode III intensity factor, out-of-plane coupling affects the magnitude of the in-plane stress intensity factors, KI and KII. Comparison of the 3D results with a 2D solution indicated that, depending on the layup angle, the 2D solution can either overpredict or underpredict the values of KI and KII by as much as 35%. Finally, the use of an effective stress intensity factor with thermoplastic or thermoset composites indicated that the 2D solution can overestimate failure loads by as much as 36% and corroborated the experimental observation that failure in composite bonded joints generally occurs as a first-ply failure of the adherends.

Original languageEnglish (US)
Pages (from-to)178-200
Number of pages23
JournalJournal of Thermoplastic Composite Materials
Volume14
Issue number3
DOIs
StatePublished - May 2001

Fingerprint

lap joints
stress intensity factors
Stress intensity factors
cracks
Cracks
composite materials
Composite materials
Elasticity
elastic properties
stress-strain relationships
bonded joints
plane stress
Thermosets
crack tips
Eigenvalues and eigenfunctions
Crack tips
Thermoplastics
eigenvectors
expansion

Keywords

  • Bimaterial interfaces
  • Bonded joints
  • Fracture mechanics
  • Interlaminar cracks
  • Off-axis plies
  • Out-of-plane coupling
  • Stress intensity factors
  • Stress singularities
  • Three-dimensional effects

ASJC Scopus subject areas

  • Ceramics and Composites

Cite this

@article{6a34fd2f75984c93a260f278879f771f,
title = "Out-of-plane coupling effects on stress intensity factors at interface cracks in composite lap joints",
abstract = "The existence of off-axis plies in adhesively bonded lap joints leads to anisotropic stress-strain relationships where the in-plane and out-of-plane components of stress and deformation (in a plane perpendicular to the width of the joint) are coupled. In this paper, the anisotropic elasticity solution near a bimaterial crack tip is formulated using an eigenfunction expansion of the stresses and displacements. This elasticity solution is subsequently used in conjunction with finite elements in a global/local method in order to determine mode I, mode II, and mode III stress intensity factors. Numerical results for [(±Θ)2]s layups indicated that an out-of-plane mode III stress intensity factor, KIII, arises when off-axis plies are present even though the loading is in-plane. Depending on the layup angle and crack location, KIII can be as large as 43{\%} of KI and 55{\%} KII. It was also found that, in addition to producing a mode III intensity factor, out-of-plane coupling affects the magnitude of the in-plane stress intensity factors, KI and KII. Comparison of the 3D results with a 2D solution indicated that, depending on the layup angle, the 2D solution can either overpredict or underpredict the values of KI and KII by as much as 35{\%}. Finally, the use of an effective stress intensity factor with thermoplastic or thermoset composites indicated that the 2D solution can overestimate failure loads by as much as 36{\%} and corroborated the experimental observation that failure in composite bonded joints generally occurs as a first-ply failure of the adherends.",
keywords = "Bimaterial interfaces, Bonded joints, Fracture mechanics, Interlaminar cracks, Off-axis plies, Out-of-plane coupling, Stress intensity factors, Stress singularities, Three-dimensional effects",
author = "Penado, {F E}",
year = "2001",
month = "5",
doi = "10.1106/5DF5-CCE9-F7GV-T7YC",
language = "English (US)",
volume = "14",
pages = "178--200",
journal = "Journal of Thermoplastic Composite Materials",
issn = "0892-7057",
publisher = "SAGE Publications Ltd",
number = "3",

}

TY - JOUR

T1 - Out-of-plane coupling effects on stress intensity factors at interface cracks in composite lap joints

AU - Penado, F E

PY - 2001/5

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N2 - The existence of off-axis plies in adhesively bonded lap joints leads to anisotropic stress-strain relationships where the in-plane and out-of-plane components of stress and deformation (in a plane perpendicular to the width of the joint) are coupled. In this paper, the anisotropic elasticity solution near a bimaterial crack tip is formulated using an eigenfunction expansion of the stresses and displacements. This elasticity solution is subsequently used in conjunction with finite elements in a global/local method in order to determine mode I, mode II, and mode III stress intensity factors. Numerical results for [(±Θ)2]s layups indicated that an out-of-plane mode III stress intensity factor, KIII, arises when off-axis plies are present even though the loading is in-plane. Depending on the layup angle and crack location, KIII can be as large as 43% of KI and 55% KII. It was also found that, in addition to producing a mode III intensity factor, out-of-plane coupling affects the magnitude of the in-plane stress intensity factors, KI and KII. Comparison of the 3D results with a 2D solution indicated that, depending on the layup angle, the 2D solution can either overpredict or underpredict the values of KI and KII by as much as 35%. Finally, the use of an effective stress intensity factor with thermoplastic or thermoset composites indicated that the 2D solution can overestimate failure loads by as much as 36% and corroborated the experimental observation that failure in composite bonded joints generally occurs as a first-ply failure of the adherends.

AB - The existence of off-axis plies in adhesively bonded lap joints leads to anisotropic stress-strain relationships where the in-plane and out-of-plane components of stress and deformation (in a plane perpendicular to the width of the joint) are coupled. In this paper, the anisotropic elasticity solution near a bimaterial crack tip is formulated using an eigenfunction expansion of the stresses and displacements. This elasticity solution is subsequently used in conjunction with finite elements in a global/local method in order to determine mode I, mode II, and mode III stress intensity factors. Numerical results for [(±Θ)2]s layups indicated that an out-of-plane mode III stress intensity factor, KIII, arises when off-axis plies are present even though the loading is in-plane. Depending on the layup angle and crack location, KIII can be as large as 43% of KI and 55% KII. It was also found that, in addition to producing a mode III intensity factor, out-of-plane coupling affects the magnitude of the in-plane stress intensity factors, KI and KII. Comparison of the 3D results with a 2D solution indicated that, depending on the layup angle, the 2D solution can either overpredict or underpredict the values of KI and KII by as much as 35%. Finally, the use of an effective stress intensity factor with thermoplastic or thermoset composites indicated that the 2D solution can overestimate failure loads by as much as 36% and corroborated the experimental observation that failure in composite bonded joints generally occurs as a first-ply failure of the adherends.

KW - Bimaterial interfaces

KW - Bonded joints

KW - Fracture mechanics

KW - Interlaminar cracks

KW - Off-axis plies

KW - Out-of-plane coupling

KW - Stress intensity factors

KW - Stress singularities

KW - Three-dimensional effects

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DO - 10.1106/5DF5-CCE9-F7GV-T7YC

M3 - Article

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VL - 14

SP - 178

EP - 200

JO - Journal of Thermoplastic Composite Materials

JF - Journal of Thermoplastic Composite Materials

SN - 0892-7057

IS - 3

ER -