Effects of geometric non-linearity on energy release rates in a realistic wind turbine blade cross section

Eder, Maximilian; Bitsche, Robert; Belloni, Federico

doi:10.1016/j.compstruct.2015.06.050

Cited by 23 publications

(21 citation statements)

References 13 publications

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“…Using this, he optimised the design of the adhesive joint configuration by analysing the stress concentrations around the bond interfaces. Eder et al [8] highlighted and investigated the use of the virtual crack closure technique (VCCT), an alternative theory to CZM, and the effect of geometric (1) leading edge adhesive joint, (2) aerodynamic panels made as a sandwich structure with foam or wood cores, (3) adhesive joint (suction side), (4) suction side spar cap, (5) suction side mould, (6) trailing edge adhesive joint, (7) pressure side mould, and (8) pressure side spar cap, and b common adhesive joint configurations widely applied in various applications non-linearity on energy release rates of adhesive cracks under bi-axial bending in a realistic wind turbine blade cross section. They concluded that taking a simplified cross-sectional slice of complex turbine blade leading edge geometries was an effective method for analysing structures with geometric non-linearity.…”

Section: Introductionmentioning

confidence: 99%

Indentation based strength analysis of adhesively bonded leading-edge composite joints in wind turbine blades

et al. 2019

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Wind turbine is a source of non-polluting renewable energy. Whether a wind turbine is viable depends entirely on the structural integrity of turbine blade. To assess the structural integrity of wind turbine blades it is necessary to investigate the loading behaviour of adhesively bonded composite joints. Finite element along with cohesive zone modelling (CZM) methods were implemented to investigate the elastic indentation contact of adhesively bonded leading-edge composite joints in wind turbine blades. The CZM was validated by replicating existing experimental and numerical work on composite-to-adhesive bonds applied to wind turbine structures. This validated model was then used to investigate the structural integrity of a variety of leading-edge joint configurations, adhesive thicknesses and bond finishes under indentation. Numerical results showed that an off-centre adhesive joint configuration was desirable and capable of withstanding between 39 and 96% more load than centred joints. Direct indenter to adhesive contact was shown to reduce fracture resistance by up to 4.7%. An adhesive joint based on a lap joint configuration was proposed as an alternative to current designs. Keywords Wind turbine blade • Adhesive joints • Stress analysis • Finite element method • Indentation Abbreviations CFRP Carbon fibre reinforced polymers CZM Cohesive zone model DCB Double cantilever beam ENF End-notch flexure FE Finite element GFRP Glass fibre reinforced polymers VCCT Virtual crack closure technique List of symbols E Elastic modulus F s Slow down force G C Critical fracture energy release rate G IC Critical fracture energy release rate (Mode I) G IIC Critical fracture energy release rate (Mode II) G IIIC Critical fracture energy release rate (Mode III) G I Fracture energy release rate (Mode I) G II Fracture energy release rate (Mode II) G III Fracture energy release rate (Mode III) K c Stress intensity factor (fracture toughness) m Mass s Slow down distance v Velocity n

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Section: Introductionmentioning

confidence: 99%

Indentation based strength analysis of adhesively bonded leading-edge composite joints in wind turbine blades

et al. 2019

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“…The researchers try to consider nonlinear phenomena for structures and devices. Some examples of nonlinear mechanical systems phenomena occur in aerospace sector, guyed tower and rotating wind turbine blade [4,5]. In aeronautic, a new aircraft designs with light weight and high aspect-ratio wing provides advantage in producing a higher lift-to-drag ratio [6].…”

Section: Introductionmentioning

confidence: 99%

Numerical And Experimental Investigations of Nonlinearity Behaviour In A Slender Cantilever Beam

et al. 2018

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Nonlinear problem is always occur in slender structures that are usually characterized by large displacements and rotations but small strains. Linear design assumption could lead to premature failure if the structure behaves nonlinearly. In this paper, the static displacement of a slender beam subjected to point load is investigated numerically by incorporating the large amplitude of the displacement. Two types of numerical analyses are performed at a full-scale finite element model which is linear static and geometric nonlinear implicit static. the results of the FEA linear static analysis are compared with the results from the FEA geometric nonlinear implicit static analysis. It shows that very high different load-displacement value response. Experimental static displacement test has been performed to validate both numerical results.

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“…These large deflections, in conjunction with high out‐of‐plane and low in‐plane cross‐section stiffness, lead to geometric non‐linear in‐plane cross‐section deformations. This bending‐induced in‐plane warping effect—also referred to as Brazier effect or cross‐section ovalisation as investigated for blades by Damkilde and Lund as well as Cecchini and Weaver —is typically associated with mode‐I and mode‐II SERRs as discussed in . The formation of geometrically non‐linear lengthwise wave deformation patterns in the trailing edge increases the severity.…”

Section: Introductionmentioning

confidence: 99%

A comprehensive investigation of trailing edge damage in a wind turbine rotor blade

2016

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Wind turbine rotor blades are sophisticated, multipart, lightweight structures whose aeroelasticity-driven geometrical complexity and high strength-to-mass utilization lend themselves to the application of glass-fibre or carbon-fibre composite materials. Most manufacturing techniques involve separate production of the multi-material subcomponents of which a blade is comprised and which are commonly joined through adhesives. Adhesive joints are known to represent a weak link in the structural integrity of blades, where particularly, the trailing-edge joint is notorious for its susceptibility to damage. Empiricism tells that adhesive joints in blades often do not fulfil their expected lifetime, leading to considerable expenses because of repair or blade replacement. Owing to the complicated structural behaviour-in conjunction with the complex loading situation-literature about the root causes for adhesive joint failure in blades is scarce. This paper presents a comprehensive numerical investigation of energy release rates at the tip of a transversely oriented crack in the trailing edge of a 34m long blade for a 1.5MW wind turbine. First, results of a non-linear finite element analysis of a 3D blade model, compared with experimental data of a blade test conducted at Danmarks Tekniske Universitet (DTU) Wind Energy (Department of Wind Energy, Technical University of Denmark), showed to be in good agreement. Subsequently, the effects of geometrical non-linear cross-section deformation and trailing-edge wave formation on the energy release rates were investigated based on realistic aeroelastic load simulations. The paper concludes with a discussion about critical loading directions that trigger two different non-linear deformation mechanisms and their potential impact on adhesive trailing-edge joint failure.

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Effects of geometric non-linearity on energy release rates in a realistic wind turbine blade cross section

Cited by 23 publications

References 13 publications

Indentation based strength analysis of adhesively bonded leading-edge composite joints in wind turbine blades

Indentation based strength analysis of adhesively bonded leading-edge composite joints in wind turbine blades

Numerical And Experimental Investigations of Nonlinearity Behaviour In A Slender Cantilever Beam

A comprehensive investigation of trailing edge damage in a wind turbine rotor blade

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