On matrix crack growth in quasi-isotropic laminates—I. Experimental investigation

Tong, Jie; Guild, FJ; Ogin, S.L.; Smith, Paul A.

doi:10.1016/s0266-3538(97)00080-8

Cited by 162 publications

(71 citation statements)

References 22 publications

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“…In pristine layered Multi-Directional (MD) laminates, the first damage mode usually takes the form of off-axis cracks tunnelling through the laminate layers, followed by delamination and fibre breakage leading to ultimate structural failure. This failure sequence has been reported by several authors on the coupon scale [2][3][4] and on the structural scale [5], where it was clear that a predominant failure mode of a wind turbine blade subjected to fatigue loading was off-axis cracks, although not specifically mentioned by the authors. It is particularly important to predict the offaxis crack damage mode, since these cracks promote other damage modes such as delamination and fibre breakage [6,7] and are linked directly to the stiffness degradation observed in composite laminates during fatigue loading [3,4,8,9].…”

Section: Introductionsupporting

confidence: 73%

“…The number of cycles to initiation of the first observed off-axis crack in fatigue have been reported by numerous investigations, e.g. [2,3,9,18], with the purpose of establishing an S-N curve to describe the relationship between the stress and the number of cycles required to initiate the first crack. However, the temporal resolution of the measurements is not provided, which may influence the derived results.…”

Section: Crack Initiationmentioning

confidence: 99%

“…This is the reason why is often referred to as the characteristic life. Since is derived based on all independent initiated cracks in the measuring volume it is expected to be a more robust and accurate measure for deriving the material S-N curve as compared to the case of using the first crack initiation results as done in [2,3,9,18]. Figure 9(b) shows the characteristic life plotted in the form of applied stress vs. the Weibull scale parameter and fitted with an S-N power-law of the type .…”

Section: Crack Initiationmentioning

confidence: 99%

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Fatigue damage evolution in GFRP laminates with constrained off-axis plies

Glud¹,

Dulieu-Barton²,

Thomsen³

et al. 2017

Composites Part A: Applied Science and Manufacturing

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., "Fatigue damage evolution in GFRP laminates with constrained off-axis plies", Composites Part A, http://dx.doi. org/10.1016/j.compositesa.2017. method with a data mining approach and applying these to large data sets obtained during fatigue tests. It is shown that for a constant stress level, the stochastic nature of off-axis crack initiation and crack growth is accurately modelled by the Weibull distribution, with the distribution parameters being efficiently derived using the developed approach. The data-rich characterisation provides new insight in the crack density evolution process for VA and C-T loading, as well as derived Weibull distribution parameters in combination with the classical S-N curves and Paris' Law relationship.Hence, providing an improved approach that includes the stochastic and deterministic information for physically based modelling of crack density evolution for fatigue loading.Glud, J.A., Dulieu-Barton, J.M., Thomsen, O.T. and Overgaard, L.C.T., "Fatigue damage evolution in GFRP laminates with constrained off-axis plies", Composites Part A, http://dx

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Section: Introductionsupporting

confidence: 73%

Section: Crack Initiationmentioning

confidence: 99%

Section: Crack Initiationmentioning

confidence: 99%

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Fatigue damage evolution in GFRP laminates with constrained off-axis plies

Glud¹,

Dulieu-Barton²,

Thomsen³

et al. 2017

Composites Part A: Applied Science and Manufacturing

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“…In general, transverse matrix cracking/splitting is the first damage mode occurring within the laminate due to relatively low resin strength/ stiffness (Nairn 2000). But this won't result in ultimate failure of the composite, although degradation of its stiffness may occur (Tong et al 1997). With cracks propagating in the matrix, delaminations can be initiated between plies, which could eventually lead to fibre breakage and loss of functionality depending on load or energy level available .…”

Section: Introductionmentioning

confidence: 99%

Modelling low velocity impact induced damage in composite laminates

Shi

Soutis

2017

Mech Adv Mater Mod Process

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The paper presents recent progress on modelling low velocity impact induced damage in fibre reinforced composite laminates. It is important to understand the mechanisms of barely visible impact damage (BVID) and how it affects structural performance. To reduce labour intensive testing, the development of finite element (FE) techniques for simulating impact damage becomes essential and recent effort by the composites research community is reviewed in this work. The FE predicted damage initiation and propagation can be validated by Non Destructive Techniques (NDT) that gives confidence to the developed numerical damage models. A reliable damage simulation can assist the design process to optimise laminate configurations, reduce weight and improve performance of components and structures used in aircraft construction.

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“…In fact a characteristic of these materials is that damage spreads throughout a large area of the coupon (at least in straight sided tensile specimens) before becoming localised and causing failure [18]. Matrix cracking always starts in the most off-axis ply and fatigue matrix cracking starts at lower strains than during quasi-static testing [19]. These cracks always start at the edge of the coupon [19] and appear to be significantly suppressed (approximately two decades) in structures with no free edges [17] [20].…”

Section: Introductionmentioning

confidence: 99%

A preliminary design methodology for fatigue life prediction of polymer composites for tidal turbine blades

Kennedy

Leen

Brádaigh

2012

Proceedings of the Institution of Mechanical Engineers, Part L:

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Tidal turbine blades experience significant fatigue cycles during operation and it is expected that fatigue strength will be a major consideration in their design. Glass fibre reinforced polymers (GFRP) are a candidate low-cost material for this application. This paper presents a methodology for preliminary fatigue design of GFRP tidal turbine blades. The methodology combines (i) a hydrodynamic model for calculation of local distributions of fluid-blade forces, (ii) a finite element structural model for prediction of blade strain distributions, (iii) a fatigue damage accumulation model, which incorporates mean stress effects, and (iv) uniaxial fatigue testing of two candidate GFRP materials (for illustrative purposes). The methodology is applied here to the preliminary design of a three-bladed tidal turbine concept, including tower shadow effects, and comparative assessment of pitchregulated and stall-regulated control with respect to fatigue performance. INTRODUCTIONThe emerging field of ocean energy is naturally turning to composite materials because of their perceived non-corrosive properties in the harsh saltwater environment as well as their high specific strength and stiffness. Tidal turbines are to the forefront due to their reliable and predictable power delivery to the grid and the absence of overload conditions. A number of different designs of tidal turbines are already at utility scale trials. A low-solidity, two-bladed turbine, similar to wind turbines, and a high solidity, multi-blade, ducted rotor are presently undergoing customer testing [1]. Wave energy converters are also under consideration with a number of devices at full size prototype stage [2]. Glass-fibre reinforced polymers (GFRP) are candidate low-cost materials for the blades of tidal turbines and the energy collection surfaces of wave devices. It is therefore important to understand the durability and performance of such materials for these applications. A 10 rpm tidal turbine would see approximately 4 million revolutions per year and wave devices will encounter approximately the same number of waves. Therefore fatigue failure will need to be considered in the design of these devices.The structural properties of GFRP materials depend on orientation of the fibres, polymer type and fibre/polymer volume fraction. One of the main advantages of fibre reinforced materials is the ability to align the strong, stiff fibres with the main loads and thereby use the material to its maximum advantage. There are situations, however, particularly in relation to emerging technologies e.g. ocean energy, where (i) the loads are not very well understood, or (ii) the loads are complex and multi-directional in nature, for which a class of fibre-reinforced laminates called quasi-isotropic (QI) can be used. The typical QI layup has equal numbers of fibres at 0, 45, 90, and 135 degrees although many other configurations are possible. Often QI laminates are used for an entire structure or they can be implemented locally on other laminate types by addin...

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On matrix crack growth in quasi-isotropic laminates—I. Experimental investigation

Cited by 162 publications

References 22 publications

Fatigue damage evolution in GFRP laminates with constrained off-axis plies

Fatigue damage evolution in GFRP laminates with constrained off-axis plies

Modelling low velocity impact induced damage in composite laminates

A preliminary design methodology for fatigue life prediction of polymer composites for tidal turbine blades

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