The Rekovind2 project, financed by the Swedish Energy Agency, focuses on digitizing wind turbine blade streams for reuse and recycling. This is of the utmost importance to enable new, more circular technical solutions that can replace today’s non-sustainable recycling, i.e. landfill and incineration of wind turbine blades. In this report, the work carried out to map the wind turbine blades in service in Sweden is presented. The digital platform intended to make possible the re-use of blades reaching end-of-life is build around key features that will be required for re-use: blade database with all needed informations on the blade (age, damages, material, model, ...), map with blades geolocation, digital tool to help blade processing such as cutting, and information on what can be done with EoL blades.

I regleringsbrevet för 2023 fick Energimyndigheten i uppdrag av regeringen att utreda hur solcellspaneler och vindturbinblad till vindkraftverk i högre utsträckning ska kunna tas om hand på ett giftfritt och cirkulärt sätt i enlighet med avfallshierarkin. Redovisningen av detta regeringsuppdrag, rapporten Från avfall till resurs – Förslag för en mer cirkulär hantering av solcellspaneler och vindturbinblad, ER 2024:11, baseras på denna underlagsrapport som har tagits fram av forskningsinstitutet RISE på uppdrag av Energimyndigheten. Analyser, slutsatser och förslag/rekommendationer som framförs i rapporten är författarnas egna.En fortsatt utbyggnad av fossilfri elproduktion är av stor vikt för att vi ska kunna nå Sveriges energi- och klimatmål. För att utbyggnaden i sig ska vara hållbar är det viktigt att vi redan nu planerar för hur avfallet från dessa elproduktionsanläggningar ska förebyggas, minimeras och sedan hanteras.Det finns redan i dagsläget aktörer som har utvecklat och håller på att utveckla ett flertal olika lösningar för ökad cirkularitet. Dessa möjligheter kan tas tillvara och främjas genom regelbunden kartläggning och genom att arbeta gemensamt inom EU. Genom ett sådant arbete finns det också större möjligheter att etablera industriella värdekedjor i Sverige för hanteringen av avfallet från solcellspaneler och vindturbinblad.En cirkulär hantering av avfall ger ett betydligt mindre avtryck på miljön än det som en linjär hantering ger upphov till. Det är viktigt att de aktörer som tillhandahåller fossilfri elproduktion tar ansvar under hela livscykeln och att det finns goda förutsättningar för aktörerna att göra det.

Unidirectional laminates have been tested under uniaxial transverse compression and under biaxialtransverse compression. Failure occurred by shear in an inclined failure plane parallel to the fibres.The transverse shear response of the material on the failure plane was evaluated from the tests. In thebiaxial tests, the failure load was considerably higher than in the uniaxial tests. For a given transverseshear strain the transverse shear stress was also higher in the case of biaxial compression. It is alsoshown that using waisted specimens instead of prismatic specimens does not seem to bring noticeablebenefits for through-thickness uniaxial compression tests. The experimental results presented here areimportant input to the development and the validation of damage models of fibre reinforced polymermaterials accounting for the matrix nonlinear response in shear and compression.

A complete database of the mechanical properties of an epoxy polymer reinforced with uni-weave carbon fibre non-crimp fabric (NCF) is established. In-plane and through-the-thickness tests were performed on unidirectional laminates under normal loading and shear loading. The response under cyclic shear loading was also measured. The material has been characterised in terms of stiffness, strength, and failure features for the different loading cases. The critical energy release rates associated with different failure modes in the material were measured from interlaminar and translaminar fracture toughness tests. The stress–strain data of the tensile, compressive, and shear test specimens are included. The load–deflection data for all fracture toughness tests are also included. The database can be used in the development and validation of analytical and numerical models of fibre reinforced plastics (FRPs), in particular FRPs with NCF reinforcements.

The experimental evaluation of the shear response of fibre-reinforced plies is a requirement for accurate material models predicting progressive damage. In the first part of the paper, the quality of the Iosipescu shear test is investigated with full-field strain measurements and finite element analyses. In the second part, the in-plane and through-thickness shear response of an orthotropic carbon/epoxy uni-weave non-crimp fabric composite are compared, and the stress–strain curves used as input for two continuum damage mechanics models. Both models were able to predict accurately the nonlinear shear behaviour of the material. The model parameters and the damage evolution laws could easily be extracted from cyclic Iosipescu tests.

Crush tests have been performed on flat unidirectional non-crimp fabric (NCF) coupons with differentfibre orientations as part of the validation of a ply-based damage model for crash. The fibre off-axisangle with respect to the crushing direction ranged from 0º to 90°. The results of the tests indicate thatthe crush stress remains unchanged for off-axis angles between 0° and 15°. The failure mode in thesespecimens was out-of-plane kinking. For 20° and 25° off-axis angles the crush stress dropped 20% andevidence of out-of-plane kinking were harder to find. For 45° off-axis angle a network of matrixcracks develops in the specimen and for 90° off-axis angle a brittle shear failure is observed. It issuggested that the out-of-plane kinking is promoted because of the natural waviness of NCF materialsand that the high in-plane shear stress generated from 20-25° off-axis loading results in a transitionfrom out-of-plane kinking to in-plane kinking. These hypotheses need, however, to be verified by anextended failure analysis of the crush specimens.

More fundamental test methods are needed to assist the development of physically based and truly predictive simulation tools for composite materials under crash conditions. In this paper, a unidirectional flat specimen that can be used to validate the predicted behaviour from a simulation to the physical behaviour in the experiment is developed. A systematic experimental investigation is conducted to evaluate the influence of the trigger geometry on the crushing response by selecting two trigger types and different trigger angles. For longitudinal crushing, the traditional bevel trigger leads to out-of-plane failure by splaying with a limited amount of in-plane fracture, while the proposed trigger achieves a high amount of compressive fragmentation failure. For transverse crushing, the symmetry of the proposed new trigger improves the specimen stability during the crushing process. It is also observed that the weft threads of the unidirectional fabric reinforcement used for the tests have a strong influence on the longitudinal crushing response. The boundary conditions of the test and the information on the specimen failure gleaned from video recordings and microscopic inspections are discussed in order to facilitate a future correlation with modelling results. © 2017, © The Author(s) 2017.

This paper details a complete crush model for composite materials with focus on shear dominated crushing under a three-dimensional stress state. The damage evolution laws and final failure strain conditions are based on data extracted from shear experiments. The main advantages of the current model include the following: no need to measure the fracture toughness in shear and transverse compression, mesh objectivity without the need for a regular mesh and finite element characteristic length, a pressure dependency of the nonlinear shear response, accounting for load reversal and some orthotropic effects (making the model suitable for noncrimp fabric composites). The model is validated against a range of relevant experiments, namely a through-the-thickness compression specimen and a flat crush coupon with the fibres oriented at 45° and 90° to the load. Damage growth mechanisms, orientation of the fracture plane, nonlinear evolution of Poisson's ratio and energy absorption are accurately predicted.

This paper details a complete crush model for composite materials with focus on shear dominated crushing under a3D stress state. The damage evolution laws and nal failure strain conditions are based on data extracted from shearexperiments. The main advantages of the current model are: no need to measure the fracture toughness in shear andtransverse compression, mesh objectivity without the need for a regular mesh and nite element characteristic length, apressure dependency of the shear response, account for load reversal and for some orthotropic eects (making the modelsuitable for Non-Crimp Fabric composites). The model is validated against a range of relevant experiments, namely athrough-the-thickness compression specimen and a at crush coupon with the bres oriented at 45 and 90 degrees to theload. Damage growth mechanisms, orientation of the fracture plane, nonlinear evolution of Poisson's ratio and energyabsorption are accurately predicted.

A progressive damage model for matrix compression is complemented with matrix tension in a physically based manner. The interaction of damage mechanisms undergoes a preliminary validation using single elements. The crushing response is validated with two different flat specimens with the fibres oriented transversely and at 45 degrees to the load. The model combines friction with damage to model the shear response accurately, which is necessary for reliable crush simulations. The behaviour in tension is history dependent, i.e. the model accounts for the stiffness reduction and strength to carry load in tension when previously damaged occurs in compression.The validation is performed against different tests showing the reliability of the model for different fibre orientation, specimen geometry and multiaxial loading scenarios. The crush response is well captured as well as the geometry and location of the different damage mechanisms.

Tape-based discontinuous composite is a relatively new type of composite material that offers improved mechanical properties for similar process-ability compared to Sheet Moulding Compound or Bulk Moulding Compound. This makes it potentially attractive for the automotive industry. In this paper, a thin-ply carbon fibre reinforced polypropylene-based discontinuous composite is studied. Mechanical tests are performed to obtain the tensile, compression and shear behaviour of the material. The energy absorption via tearing is also studied to assess the suitability of the material for energy absorption applications, such as crash-boxes. The tearing test results show a large degree of plastic deformation and an advancing damage front leading to higher specific energy absorption via tearing compared to conventional composite materials. © 2021 The Author(s). 

In this paper we apply a recently developed methodology to assess the compressive strength of an aero-engine component based on measured fibre misalignment angles. The component is a fan outlet guide vane made from a carbon fibre reinforced polymer, which was manufactured and tested by GKN Aerospace in Sweden. The main novelty with this work is that kink-band formation is predicted from measurements of fibre misalignment angles with high spatial resolution in a real component. In addition, we validate the recently published “defect severity model” on unidirectional specimens of the same material system as the aerospace component. We confirm high accuracy of the model for prediction of compressive strength on unidirectional composite laminates. Further work is however needed to extend the methodology for cases where progressive damage leads to final failure.