Computational micromechanics of fiber kinking in unidirectional FRP under different environmental conditions

Naya, F.; Herráez, M.; Lopes, C.S.; González, C.; Veen, Sjoerd van der; Pons, François

doi:10.1016/j.compscitech.2017.03.014

Cited by 118 publications

(48 citation statements)

References 43 publications

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“…In addition, the CP specimen presents several advantages over previous approaches: the CP material is more readily available and multiple different orientations can be obtained from a single laminate, making it a more versatile, costeffective and convenient method to test different shear-longitudinal compression ratios. Finally, the obtained results were used to evaluate the fibre kinking theory proposed by Pinho in [5], which is one of the few criteria for this type of failure with a sound physical explanation implemented in three dimensions and has been shown to produce good results in the uniaxial compression case [23]. This theory consists in rotating the macroscopic stress state to an internal misalignment frame, Figure 13 (a), obtained by adding the local shear strain to the initial fibre waviness.…”

Section: Discussion and Analysismentioning

confidence: 99%

A study on the longitudinal compression strength of fibre reinforced composites under uniaxial and off-axis loads using cross-ply laminate specimens

Thomson

Cui

Erice

et al. 2019

Composites Part A: Applied Science and Manufacturing

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Longitudinal compression testing of unidirectional FRP laminates remains a challenge due to the difficulty in applying high compressive loads without stress concentrations and boundary effects leading to premature failure. This work aims to critically evaluate different specimen designs and laminate configurations, cross-ply in particular, for the determination of longitudinal compression properties of unidirectional plies. To this end, a comprehensive experimental campaign has been carried out, comparing strength, stiffness, and failure modes across different specimen designs and laminate configurations. The investigated cross-ply specimens produced comparable results without many of the issues observed in the testing unidirectional material and, therefore, are strongly recommended for the determination of longitudinal compressive strength. Finally, the cross-ply material was tested under off-axis compression to study the effects of shear on the longitudinal compression strength using a series of compression specimens cut at different angles between 0 and 15° to the direction of the laminate.

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Section: Discussion and Analysismentioning

confidence: 99%

A study on the longitudinal compression strength of fibre reinforced composites under uniaxial and off-axis loads using cross-ply laminate specimens

Thomson

Cui

Erice

et al. 2019

Composites Part A: Applied Science and Manufacturing

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“…Interfacial properties under different cure pressures were used as input parameters to investigate the effect of interfacial shear strength on the ply-level intralaminar behaviour. Damage due to longitudinal tensile/compressive stresses is not modelled in this work, as this has been previously reported [54].…”

Section: Micromechanical Modelmentioning

confidence: 99%

The role of interfacial properties on the intralaminar and interlaminar damage behaviour of unidirectional composite laminates: Experimental characterization and multiscale modelling

Tan

Naya

Yang

et al. 2018

Composites Part B: Engineering

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108

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The development of the latest generation of wide-body passenger aircraft has heralded a new era in the utilisation of carbon-fibre composite materials. One of the primary challenges facing future development programmes is the desire to reduce the extent of physical testing, required as part of the certification process, by adopting a 'certification by simulation' approach. A hierarchical bottom-up multiscale simulation scheme can be an efficient approach that takes advantage of the natural separation of length scales between different entities 2 (fibre/matrix, ply, laminate and component) in composite structures. In this work, composites with various fibre/matrix and interlaminar interfacial properties were fabricated using an autoclave under curing pressures ranging from 0 to 0.8 MPa. The microstructure (mainly void content and spatial distribution) and the mechanical properties of the matrix and fibre/matrix interface were measured, the latter by means of nano-indentation tests in matrix pockets, and fibre push-in tests. In addition, the macroscopic interlaminar shear strength was determined by means of three-points bend tests on short beams. To understand the influence of interfacial properties on the intralaminar failure behaviour, a high-fidelity microscale computational model is presented to predict homogenized ply properties under shear loading. Predicted ply material parameters are then transferred to a mesoscale composite damage model to reveal the interaction between intralaminar and interlaminar damage behaviour of composite laminates.

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“…There are several types of defects at the scale of the fiber and matrix (microscale) including fiber/matrix debonding, fiber waviness, dry fibers, and resin rich areas. Fiber waviness is a common defect that directly reduces the stiffness and strength of composites [17,18,19]. Unlike the fiber waviness defect, studies on the effect of resin pockets in microstructures are not widely reported in the literature.…”

Section: Introductionmentioning

confidence: 99%

Numerical analysis of resin-rich areas and their effects on failure initiation of composites

Ghayoor

Marsden

Hoa

et al. 2019

Composites Part A: Applied Science and Manufacturing

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Resin-rich areas in composite laminates can occur as inter-laminar resin 'layers' between plies or as intra-laminar resin 'pockets' within a single layer. In this work, numerical methods are used to study the effects of resin pockets on the transverse stiffness and failure initiation of carbon-epoxy composites. Random, or non-uniform, representative volume elements (RVE) with and without embedded resin pockets were studied. Three different types of samples with predefined volume fractions (V f) were analyzed, and data relating to the influence of resin pockets on homogenized stiffness and the strain at which failure initiates was collected and reported. Based on a control sample for each volume fraction, two methods were used to create RVE samples with resin pockets. In one, the distances between fibers were maintained and fibres removed to create the resin pocket, with a corresponding decrease in (V f). In the second method, the V f was maintained and fibers were moved to create the resin pocket, with a corresponding reduction in the distance between fibers. It is shown that intra-laminar resin pockets can reduce both the stiffness and the failure strain of composite materials. Stiffness was reduced in samples where the resin pocket resulted in a reduced volume fraction. For samples with the same volume fraction, particularly for high V f composites (e. g. 60%), the failure initiation strain in the matrix was, on average, 20% lower for samples with resin pockets compared to samples without resin pockets.

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Computational micromechanics of fiber kinking in unidirectional FRP under different environmental conditions

Cited by 118 publications

References 43 publications

A study on the longitudinal compression strength of fibre reinforced composites under uniaxial and off-axis loads using cross-ply laminate specimens

A study on the longitudinal compression strength of fibre reinforced composites under uniaxial and off-axis loads using cross-ply laminate specimens

The role of interfacial properties on the intralaminar and interlaminar damage behaviour of unidirectional composite laminates: Experimental characterization and multiscale modelling

Numerical analysis of resin-rich areas and their effects on failure initiation of composites

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