Carbon composites based on multi-axial multi-ply stitched preforms – Part 6. Fatigue behaviour at low loads: Stiffness degradation and damage development

Vallons, Katleen; Zong, Mengmeng; Lomov, Stepan Vladimirovitch; Verpoest, Ignace

doi:10.1016/j.compositesa.2007.03.003

Cited by 49 publications

(23 citation statements)

References 13 publications

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“…However, concerning the shear behavior, fundamental aspect of the draping and stamping processes, this system is restricted to small angles (less than 8°) and must be supplemented by experiments at large shear strains like picture frame test. The description of the geometry of the preform [1,4], the characterization of the internal structure of the final composite part [5,6], the study of damage and fracture of the matrix and reinforcement set [7,8] or the fatigue behavior [9] are studied areas for the global characterization of the mechanical behavior of this material.…”

mentioning

confidence: 99%

Analyses of the Deformation Mechanisms of Non-Crimp Fabric Composite Reinforcements during Preforming

Bel

Boisse

Dumont³

2011

Appl Compos Mater

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confidence: 99%

Analyses of the Deformation Mechanisms of Non-Crimp Fabric Composite Reinforcements during Preforming

Bel

Boisse

Dumont³

2011

Appl Compos Mater

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“…In the case of NCF composites, however, with their fi bre bundles slightly compacted by the stitching yarn and surrounded by the more ductile matrix material, Gagel et al suggested that the stress concentrations at the crack tip may be released. Vallons et al (2007) monitored the damage development in a biaxial carbon fi bre NCF composite for tensile-tensile fatigue loads up to stresses corresponding to the initiation of damage in a static tensile test. Radiography revealed extensive matrix cracking in the off-axis oriented plies.…”

Section: Damage Developmentmentioning

confidence: 99%

Fatigue in non-crimp fabric composites

Vallons¹

2011

Non-Crimp Fabric Composites

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Knowledge of the fatigue behaviour of a material is essential for safe use in structural applications. This chapter discusses recent fi ndings concerning the tensile fatigue properties of non-crimp fabric (NCF) composites (fatigue life, stiffness evolution and damage development). It is also briefl y describes how fatigue infl uences the residual static performance of these materials.In most applications, materials are not simply subjected to static loading conditions; other loading modes are often equally, or sometimes more, important. For many applications, like cars and aeroplanes, it is very important to know how the material behaves under fatigue. This chapter focuses on the fatigue behaviour of non-crimp fabric (NCF) composites. The discussions are limited to tensile fatigue loading conditions.In most metals, tensile fatigue is characterised by the initiation of a single crack that then propagates until catastrophic failure, which occurs with little warning. Unlike metals, however, composite materials are inhomogeneous and anisotropic on the mesoscale. They accumulate damage in a general, rather than a localised, fashion, and, most often, failure does not occur by the propagation of a single macroscopic crack. The microstructural mechanisms of fatigue damage in a composite can include fi bre breakage, matrix cracking, debonding, and delamination. These damage modes may occur independently or interact with each other, and the dominant mechanism can depend on material variables and testing conditions. This makes fatigue in composites a very complex issue (Harris, 2003).The present chapter deals with fatigue in one particular type of continuous fi bre composite, the non-crimp fabric (NCF) composites. While fatigue in Unidirectional (UD) based laminates and woven fabric laminates has been investigated widely in the past, the knowledge about the specifi c fatigue properties of NCF composites is still relatively limited. The following paragraph discusses a number of recent fi ndings concerning the fatigue life, damage development and stiffness evolution of composites based on NCFs. The infl uence of the composite orientation compared to the loading direction is also briefl y considered. After that, the infl uence of fatigue loading on the residual static properties of the composite material is looked into.

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“…Sun et al [13] tested the high-strain-rate compressive properties of E-glass/epoxy MWK composites and their results indicated that the stress strain curves, compressive stiffness, maximum stress and corresponding strain are strain rate sensitive. Recently, Vallons et al [14] studied the tensiletensile fatigue properties of 0 o /90 o multi-ply carbon fiber fabric reinforced epoxy composites and their results shows that specimens in machine and cross direction did not fail up to 10 6 cycles while specimens in bias direction had an average fatigue life of 3×10 5 cycles. Li et al [15] reported tensile fatigue behaviour and failure mechanism of 3D MWK glass/epoxy composites.…”

Section: Introductionmentioning

confidence: 97%

Mechanical response and failure of 3D MWK carbon/epoxy composites at cryogenic temperature

Duan

Jiang

et al. 2015

Fibers Polym

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Static tensile and bending experiments are conducted on 3D MWK carbon/epoxy composites with two types of fiber architecture at room and cryogenic temperature (low as -196 o C). Macro-Fracture morphology and SEM micrographs are examined to understand the deformation and failure mechanism. The results show that tensile stress vs. strain curves have linear elastic feature up to failure; while the load-deflection curves for composites with large fiber orientation angle have pronounced nonlinear and failure in steps. Meanwhile, tensile and bending properties at liquid nitrogen temperature have been improved significantly. Moreover, the properties can be affected greatly by the fiber architecture and these decrease with increasing fiber orientation angle at room and cryogenic temperatures. The results also show the damage and failure patterns of composites vary with the fiber architecture and temperature. The main failure for material A is 0 o fibers fracture and matrix cracking. The failure mechanism for material B is the delamination, 90 o /+45 o /-45 o fiber/matrix interface debonding and fibers tearing, as well as 0 o fibers' breakage. At cryogenic temperature, the matrix is solidified and the interfacial adhesion between fibers and matrix is enhanced significantly. However, the brittle failure becomes more obvious, more microcracks propagate and interpenetrate.

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Carbon composites based on multi-axial multi-ply stitched preforms – Part 6. Fatigue behaviour at low loads: Stiffness degradation and damage development

Cited by 49 publications

References 13 publications

Analyses of the Deformation Mechanisms of Non-Crimp Fabric Composite Reinforcements during Preforming

Analyses of the Deformation Mechanisms of Non-Crimp Fabric Composite Reinforcements during Preforming

Fatigue in non-crimp fabric composites

Mechanical response and failure of 3D MWK carbon/epoxy composites at cryogenic temperature

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