A Digital Twin for Composites Feedstock Characterisation

Koptelov A., Belnoue J.P-H., Georgilas I., Hallett S. R., Ivanov D.S.

The complexity of composites manufacturing stems from the nature of composite precursors—the combination of loosely-joined fibre network and liquid viscous resin—often heterogenous and enhanced with tougheners or functional additives. is compliant, deforms irreversibly, exhibits almost negligible resistance to axial compressive stresses and has a multitude of flow/deformation mechanisms (i.e., the internal or percolation flow of resin, flow of fibrous suspensions, densification of reinforcement, relative movement of plies, and others) – Figure 1. This makes precursors prone to defects at all stages of the composites manufacturing process.

One of the fundamental processes, universal almost for the entire range of composites manufacturing methods, is consolidation, where a composite precursor undergoes compression to engage plies in contact, squeeze out volatiles, control fibre volume fraction and thickness, obtain near-net component shapes, etc. This is a quality-critical process – deformability of composite precursors defines their susceptibility to defects, their compliance with dimensional tolerances, and the occurrence of shape distortions.

Example of flow mechanisms in the same prepreg at different processing conditions

Different forms of deformation mechanisms take place at different structural scales and often occur in parallel. It is essential to have a comprehensive understanding of all these processes to predict the evolution of precursors throughout all stages of composite processing and assess the final architecture/ properties of the composite structure. Each of these mechanisms can be described by material models with various formulations involving large number of material parameters that cannot be determined from direct experiments.

A potentially dangerous trap is that available experimental data are often limited as material testing is both complicated and time consuming. The information obtained in these tests may appear to be deficient and may not reveal all the underlying processes. In this case, property identification may provide a seemingly good fit irrespective of which mechanisms is presumed to happen. However, it does not mean that such model represents the physical reality, and it can often fail to adequately represent a wider set of experimental data. This sets a fundamental dilemma, as the material behaviour (i.e., the model selected) needs to be decided prior to conducting the tests, which introduces a strong subjective element. There is, therefore, a need for a new testing methodology that is capable to identify the deformation mechanisms as well as the relevant material properties. This methodology should be able to check different hypotheses on the deformation mechanisms and autonomously design a testing program based on the measured behaviour of the material.

We have recently developed such adaptive framework [1,2]. It presents a system for autonomous characterisation of materials subjected to an application of pressure and temperature. The system comprises conventional testing machine with heat plates and an integrated “digital brain”, which allows to make decisions on loading path in real time in a “conversation” with material and without human intervention – Figure 2.

Figure of Autonomous testing setup

Figure 2. Autonomous testing setup

The framework automatically identifies the characteristic flow processes and the properties associated with the correspondent deformation mode, such as viscosity. As a result of the process, the framework creates a reliable digital twin of the material representative over large range of processing parameters. The fully functioning prototype has been successfully tested for various material systems including toughened prepregs and dry fabrics. These curves are rather different from conventional loading programmes and show the complexity of testing needed to identify the underlying deformation mechanisms.

Figure 3. Real time characterisation (A) IMA/M21 prepreg, (B) IM7/8552 prepreg: purple - chosen trajectories, black - thickness samples response.

The digitally-driven framework does not just test the material, it defines which flow mode is happening within it and is capable of sensing fine characteristics of material state. The material properties come as a by-product of such examination. This methodology leads to reduced number of experiments while making sure that the obtained data is representative and sufficiently captures all the main features of the material behaviour.

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  1. Koptelov A., Belnoue J.P-H., Georgilas I., Hallett S. R., Ivanov, D.S. Revising testing of composite precursors – a new framework for data capture in complex multi-material systems, Composites Part A, 152 (2022) 106697.
  2. Koptelov A., Belnoue J.P-H, Georgilas I., Hallett S.R., Ivanov D.S. Adaptive real-time characterisation of composite precursors in manufacturing, Frontiers in Materials, 214.

Experimental characterisation of large in-plane shear behaviour of unidirectional carbon fibre/epoxy prepreg tapes for continuous tow shearing (CTS) process

Bohao Zhang and Byung Chul Kim*

The continuous tow shearing (CTS) process is an advanced automated fibre placement technique with the capability of steering unidirectional prepreg tapes using in-plane shear deformation, without generating tape buckling, gaps and overlaps which can be commonly seen in conventional automated fibre placement process. However, the inherent fibre misalignment within the tape can induce fibre waviness during the CTS process, which is affected by processing parameters such as temperature, shear strain rate and fibre tension. It is of importance to characterise the shear response of the prepreg tapes subjected to large shear deformation by considering the operation processing parameters used in the CTS process.

Two commonly used test methods to characterise the in-plane shear deformation of composite materials, i.e., the picture frame and bias extension tests, are not suitable for characterising unidirectional prepreg tapes. Alternatively, the off-axis tension test could be used, but specimens can only be sheared to small shear angles. Therefore, in this work, a bespoke test fixture was designed to shear unidirectional prepreg tapes at various shear strain rates and fibre tensions (see Fig. 1 which shows the working mechanism of the test fixture) and investigate the effect of shearing conditions. Digital image correlation (DIC) was used to obtain full-field strains of the specimens and to investigate the fibre realignment during shearing.

 

The bespoke in-plane shear test fixture used for shear deformation of a specimen. The image shows the specimen before (a) and after (b) shear deformation.

Figure. 1. The bespoke in-plane shear test fixture used for shear deformation of a specimen. The image shows the specimen before (a) and after (b) shear deformation.

 

The experimental results (see Fig. 2) showed that temperature is critical to the fibre realignment during shearing, as the viscosity of the resin matrix significantly influence the level of fibre re-arrangement during the shearing process, determining the shear resistance of the tape material. Thus, the local shear angle measured by DIC became closer to the global shear angle as the temperature increased. (The blue line in Fig. 2(b) is the ideal condition where the local shear angle is the same as the global shear angle, reflecting a perfect shearing.) The shear rate effect was almost negligible when the temperature was sufficiently high due to the reduction of the resin viscosity. High fibre tension allowed fibres to maintain the straightness during shearing. For the CTS process, an optimal processing temperature should be firstly determined. However, its impact on the tackiness of the resin for deposition and adhesion between the prepreg tape and the backing paper should be considered. A high fibre tension is preferable, but it requires a more robust structure of the deposition system.
Please refer to the original paper for more details. (https://doi.org/10.1016/j.compositesa.2022.107168)

Graphs showing test results

Figure. 2. Effect of temperature: (a) average material shear force vs. shear angle and (b) local shear angle vs. global shear angle for IM7/8552 specimens.

Unique Modelling Capability for Composite Manufacturing

The National Composite Centre (NCC) held an event focused on ‘Demystifying Digital Engineering’ on 23 March. This was an opportunity for guests to view and interact with a range of digital technology and skills demonstrators that accelerate engineering transformation, identifying efficiencies in product, process and technology development. This will inspire the next generation of engineers to engage with tools developed in the DETI (Digital Engineering Technology & Innovation) R&D initiative.

The Bristol Composites Institute (BCI) demonstrated a simulation tool that provides uniquely fast, and accurate simulations for the manufacturing of composite components. The automated simulation tools developed are available for industry use from BCI and the NCC, which results in significant cost savings per part by reducing the need for physical trials, which could in turn eliminate one or more design cycles. The University of Bristol also contributed to DETI with 5G work on Enabling Quantum-secure 5G enabled Mobile Edge Computing (MEC) for manufacturing, through the Smart Internet Lab, and the challenge of Enabling the Digital Thread in small engineering projects in work between CFMS and the University’s Engineering Systems and Design Institute.

People looking at the BCI stand at the event  People sat watching a presentation in a conference room

BCI Doctoral Research Symposium 2023

On 4 April 2023 the Bristol Composites Institute (BCI) welcomed over 100 delegates from academia and industry to the Bill Brown Design Suite, Queen’s Building, for its annual Doctoral Research Symposium.

Attendees of BCI Symposium listening to a presentation

Doctoral students from the BCI, including 38 students from the EPSRC CDT in Composites Science, Engineering and Manufacturing (CoSEM CDT), showcased their innovative composites research through an impressive display of posters and presentations. 

Delegates were treated to a rapid-fire journey through the cutting-edge of composites research, with 25 presentations on topics spanning all three themes of the institute. Slides can be found on the Symposium webpage; recordings will be added to the BCI YouTube Channel 

Posters from the day were collated into an electronic Poster Booklet.

Attendee stood next to their poster board

Congratulations to all the winners of the poster competition:

  • Delegate vote: Charles de Kergariou. (Runners up: Stefania Akromah and Tom Brereton) 
  • Student vote: Stefania Akromah. (Runners up: Charlie Brewster and Charles De Kergariou) 

 

Documenting the morning’s events was local artist, Helen Frost. Her Graphic visualisation of the Symposium gives a flavour of what it was like to be there on the day.  

An artist drawing illustrations across a large canvas

Following the Symposium, students attended an industry-led discussion panel, comprising experts from Airbus UpNext, GKN Aerospace, Leonardo Helicopters, Sigmatex UK and Vertical Aerospace. Student Nuhaadh Mahid remarked that this “provided the rare opportunity to clarify industry-related questions about their current projects and reasoning behind various design choices.” 

 

To cap off the day staff and students gathered in the Wills Memorial Building for the Symposium dinner to mark the culmination of another year of hard work.

BCI Co-Director, Prof. Ole Thomsen, said: “The display of high-quality research of our BCI doctoral students was truly impressive. This was duly noted and recognised by the external attendees including project partners. It was indeed a good day for BCI!” 

Attendee stood next to their poster board

Two attendees looking at poster board

The Composites Perspectives Series

Last year the Bristol Composites Institute launched “Composites Perspectives”, a series of talks each focusing on different topics and including two composite-expert speakers. Since June 2022, the BCI has hosted three Composite Perspectives events, with the next one arranged for 11 July 2023 (details on how to register will be released soon).

The first Composites Perspectives event took place on 14 June 2022 and saw Professor Richard Oldfield (Chief Executive, UK National Composites Centre and Honorary Industrial Professor, University of Bristol) and Professor Pascal Hubert (Werner Graupe Chair on Sustainable Composites Manufacturing and Director at the Research Center for High Performance Polymer and Composite Systems, McGill University, Canada) discuss “Composites Role in Delivering Net Zero” and “Solutions for Zero Waste Composite Prepreg Processing”, respectively.

These talks became part of a wider ‘Sustainable Composites’ programme, and in September 2022 guest speaker Dr. Tia Benson-Tolle (Director, Advanced Materials and Sustainability, Boeing Commercial Aircraft) covered the importance of “Circularity and Recycling” within sustainable composites, and Professor Ian Hamerton (NCC Professor of Polymers and Sustainable Composites, University of Bristol) discussed the “High Performance Discontinuous Fibre technology (HiPerDiF)”.

The most recent event, which took place on 14 March 2023,  focused on Transformation in Engineering, with talks from Professor Mike Hinton, Consultant in Research and Technology Partnerships, High Value Manufacturing Catapult (“Engineering Transformation”) and Professor Ole Thomsen, Co-Director of Bristol Composites Institute and NCC Chair in Composites Design and Manufacture (“Towards virtual validation of composites structures – rethinking the testing pyramid approach”).

You can read about the previous events here and recordings of each session are available to view on the BCI Youtube Channel.

We look forward to inviting you to our future Composites Perspectives events.

BCI / NCC Joint Annual Conference, 10 November 2022

Last November, the Bristol Composites Institute and National Composites Centre presented the 2022 BCI NCC Joint Annual Conference, which addressed some of the key engineering challenges of our time, particularly focusing on how composites will ensure a net zero future for the UK.

The conference showcased the cross-TRL work we conduct together and how we can work in partnership with industry to advance and optimise their technology developments and fast-track innovation.

The morning session included updates from the NCC and BCI on their work in Sustainability, Hydrogen and Digital and the afternoon session focused on transitional research and how the gap between the technology readiness levels can be bridged. There was also a keynote presentation from Kate Barnard (WhatBox – Consultants facilitating mutually beneficial partnerships (whatboxltd.com)) which was followed by a panel session chaired by Michele Barbour and featured Matt Scott, Valeska Ting, Evangelos Zympeloudis, Kate Robson-Brown and Musty Rampuri and sparked plenty of thoughtful discussions between guests and speakers.

The conference, which was held at the NCC in Emersons Green, Bristol, welcomed over 60 people in-person, and had an additional 40 online attendees. Details of the 2023 joint conference will be released later in the year.

Guests listening to a presentation at the conference Guests listening to a presentation at the conference

The BCI Start-Up Companies Tackling Sustainable Engineering Innovation

The Bristol Composites Institute (BCI) has seen the beginnings of multiple start-up companies since starting as ACCIS in 2007. Playing host to a range of different engineering disciplines, it’s no surprise to see BCI start-ups tackling many problems affecting sustainable development today. Below is an overview of three start-ups led by former BCI PhD students who all graduated with PhDs from the ACCIS or CoSEM centres for doctoral training.

 

iCOMAT:

iCOMAT spun out of BCI and co-founded by CEO Dr Evangelos Zympeloudis and Dr ByungChul (Eric) Kim in 2019, and has since grown to 25 staff with blue-chip customers across Europe and USA. They are on a mission to unlock the performance of composites using their fibre steering technology and enable the lightest and the most structurally efficient composite products.

iCOMAT’s Rapid Tow Shearing (RTS) technology is the world’s first defect-free fibre steering process that enables the placement of carbon fibre tapes along curved paths without defects, enabling highly optimised structures. It was originated from the Continuous Tow Shearing (CTS) technology developed at Bristol Composites Institute. The novel process leads to drastically lighter components beyond the limit of conventional straight-fibre designs, while simultaneously lowering manufacturing cost. The process is ideal for high-volume production of complex high-performance composite components used in automotive and aerospace industries such as car frames, aircraft structures, and rocket structures. Such highly efficient structures lead to significantly lower CO2 emissions, both during use (lower weight, less fuel/energy) and during manufacture (minimum waste generation, more effective use of high-value carbon fibre materials).

 

Actuation Lab:

Simon Bates, Tom Llewellyn-Jones, and Michael Dicker have worked together as researchers for the last 10 years, optimising and simplifying technology for applications spanning the manufacturing, renewable energy, and marine sectors. In 2019, they spun Actuation Lab out of the University of Bristol, with a revolutionary approach to designing industrial hardware.

Aware that the use of hydrogen has the potential to eliminate over half the UK’s carbon emissions, but conscious of how hydrogen leaking from valves can have 11x the Global Warming Potential of CO2, they created the Dragonfly Valve. With an origami-inspired design, it requires the minimum amount of force to operate, preventing many of the leak paths of traditional valves. With help from partners like the Department for Business, Energy & Industrial Strategy, Actuation Lab is aiming to commercialise the Dragonfly Valve in time to meet the pressing needs of the UK’s energy supply.

 

 

Molydyn:

Matthew Bone started Molydyn to make computational chemistry more accessible to materials scientists, while undertaking his PhD with BCI, in June 2022. Computer modelling can provide direction to laboratory research, reducing costs, saving time, and eliminating waste. The pharmaceuticals industry has been using chemical simulation to discover new drugs for the last 40 years. However, materials science, which can benefit from using the same simulation tools, has seen minimal uptake in modelling.

To support computational chemists, Molydyn has created Atlas, a simple to use web platform that allows users to save 90% of their time pre-processing through automation. This makes using the popular modelling software LAMMPS much quicker and easier, helping new students to learn, and veteran users to research new sustainable materials faster. Molydyn has recently won a £25k innovation prize and Innovate UK funding to work with the Advanced Manufacturing Research Centre to develop case studies showcasing their ability to model polymers and plastics.

 

The BCI continues to support and promote the success of these start-ups.

BCI Co-Directors Prof. Stephen Hallett and Prof. Ole Thomsen: “We are delighted that fundamental research derived from novel and original ideas in Bristol Composites Institute has led to successful and highly innovative spin-outs. It serves as a testament to the impact of BCI’s research and the power of researchers in BCI in delivering added value to UK industry and society at large”.

Prof. Michele Barbour, Associate Pro Vice-Chancellor Enterprise & Innovation, University of Bristol: “The Bristol Composites Institute has a rich history of innovation and enterprise, and the four companies that are highlighted in this report are superb examples of that entrepreneurial spirit combined with world-leading engineering research and the commitment to realise the impact of that research outside of an academic environment. The companies Profs Thomsen and Hallett highlight here are diverse in their technology and focus but united in their aspirations to make real, lasting and impactful contributions some of our biggest global challenges, particularly to addressing climate breakdown and the need for truly sustainable processes and technologies. I will continue to follow the stories of these great companies and the inspiring people who lead them, and have no doubt that more exciting new spin-outs and start-ups will emerge from BCI in the months and years to come”.

 

 

Engineering with Origami

Armed with a large collection of origami models (which handily packed down for the journey to London), Aerospace Engineering academic Mark Schenk recently gave an outreach talk on Engineering with Origami at the Royal Institution (https://www.rigb.org/whats-on/engineering-origami). The talk attracted a diverse family audience to the lecture theatre famous for its Christmas Lectures.

A demonstration of origami being given to children

Origami, the traditional Japanese art of paper folding, has received widespread attention from mathematicians, scientists and engineers to understand its properties and explore its applications. In his talk, Mark introduced the audience to some surprising examples of folding (have you ever looked closely at Mona Lisa’s sleeves?) and a few underlying mathematical principles of origami, ultimately leading to a surprising diversity of engineering applications.

A view of the lecture hall used to give the talk on origami engineering

These applications range from designer materials with tailored properties, to self-folding origami and deployable structures in space. To get a hands-on feel for engineering origami, the audience were asked to fold their own Miura-ori sheet (a common fold pattern used in engineering origami) from a laser cut pattern, and after the talk they explored the various engineering origami models brought to the lecture.

 

The event was hosted by the Dutch Embassy in the United Kingdom, and supported by the Dutch Academic Network in the UK (DANinUK).

BCI Celebrates UTC 15 Year Anniversary

This year the Composites University Technology Centre (UTC), supported by Rolls-Royce, celebrated its 15 year anniversary. An event with talks and posters held on the 6th September was opened by the University of Bristol’s Pro-Vice Chancellor for Research and Enterprise, Prof. Phil Taylor, and followed by a dinner at The Orangery in Goldney Hall. The Composites UTC was set up in 2007 to support research into the use of composite materials for aero-engine applications and was led by Prof. Michael Wisnom for its first 10 years. In 2017, Prof. Stephen Hallett took on the Director role, leading the UTC into new technology areas such as Ceramic Matrix Composites and Hydrogen storage. Among the key achievements from the UTC have been the delivery of design and manufacturing technology for Rolls-Royce’s next generation of turbofan aeroengine, the UltraFan that will deliver a 25% reduction in fuel consumption compared to early 2000s technology. This was written up as an Impact Case Study for the REF 2021 evaluation of university research, helping the University of Bristol achieve its top 5 UK ranking.

Audience at of UTC conferencePeople in Bill Brown FoyerPeople standing outside restaurant

Promoting Sustainability by Solving Wind Turbine Design Challenges

Photo of Terence Macquart Photo of Alberto PirreraPhoto of Paul Weaver

 

 

 

by Terence Macquart (terence.macquart@bristol.ac.uk), Alberto Pirrera, and Paul Weaver 

Wind energy is recognised as one of the greenest sources of energy, meaning that energy produced from wind turbines is generally less harmful to the environment than other energy sources, especially coal and gas. In other words, substituting fossil-based fuel with wind power is a great leap toward a more sustainable future. Although wind energy today only contributes a small fraction to the total energy consumed worldwide, considerable societal efforts are being made to build more turbines and wind farms to increase our wind energy capacity and hence produce cleaner energy. This is obvious in the UK, where the government aims to reach 50 MW of installed capacity by the end of 2030, quintupling its current wind energy capacity, a formidable aspiration. 

Modern wind turbine technology has rapidly evolved over the past decades to meet the rising demand for wind power. This can be seen by the gigantic size of modern turbines, dwarfing even the largest aircraft ever created. Such large and complex systems come with engineering and sustainability challenges of their own. The wind blade research hub (WBRH) is a collaboration between the University of Bristol and the Offshore Renewable Energy Catapult (OREC) that aims to address some of these challenges, as illustrated by the breadth of our work in the Figure below. Read more about each challenge addressed by researchers at the WBRH in the following paragraph. 

Figure 1 : Overview of the wind blade research hub activities at the University of Bristol (REF: Mackie (2020) Establishing the optimal conditions for rotating arm erosion testing, materials characterisation and computational modelling of wind turbine blade rain erosion)

 

Infographic of wind turbine resaearch

Improving wind turbine performance with holistic design tools: 

Photo of Samuel Scott
by Samuel Scott; Terence Macquart terence.macquart@bristol.ac.uk

Although the design of wind turbines appears to be mature because we are repeatedly exposed to the familiar 3-bladed upwind turbine design, we know that their performance and sustainability could be further improved. However, wind turbines are also complex systems, and it is, therefore, very difficult, even sometimes impossible, to fully understand the impact that a change in design can have on the overall turbine performance. To overcome this challenge, our group has developed a sophisticated set of analysis and design tools which can navigate the complex design space of wind turbines and helps us better understand the design trade-offs we can make to improve them, leading to non-conventional designs as shown in the figure below. Reducing weight, also called light weighting, is a prime example of how such tools can help the wind industry; that is, by achieving a better understanding of aerodynamic and inertial loads on blades we can design lighter and more efficient blades, resulting in less raw materials being needed and more energy generated over the turbine lifespan. If you are interested in reading more on this topic, see the work of Dr. Samuel Scott (https://research-information.bris.ac.uk/ws/portalfiles/portal/312520978/Thesis_SamScott_Final.pdf). 

Figure 2: Non-conventional design planform of a 15MW wind turbine blade, outperforming conventional designs. AC: Aerodynamic Centre, FA: Flexural Axis

Graphic of a graph   

Wind Turbine End-of-Life:

Photo of Ian Hamerton
by Ian Hamerton & Terence Macquart

Large wind turbine blades require very strong material such as carbon fibre reinforced polymers which cannot currently be recycled effectively at large scales. As a result, at their end-of-life blades often go to landfills or are incinerated. In such cases, the costly carbon fibres making up the blade are lost, and new virgin material must be made. However, manufacturing virgin carbon fibres requires manufacturing process that are energy demanding and emit a lot of greenhouse gases. By contrast, materials that can be recycled, such as the steel making up the wind turbine tower, typically requires less energy to be made re-usable and emit less greenhouse gases (e.g. recycling steel reduces greenhouse gases emission by about 70-80%). The WBRH has two strands of research aiming to reduce the carbon footprint of wind turbines. The first one aims to rethink the design of modern turbines, using comprehensive design tools and life cycle analysis methods, to create new designs that can be made of more sustainable material. The second research strand investigates scalable ways in which we can recycle carbon fibres into new structural components, hence diminishing the overall environmental impact of wind turbine blades (Ian, Hyperdif, Lineat). 

Leading Edge Erosion: 

Photo Imad Ouachan Photo of Robbie Heering

by Imad Ouachan and Robbie Heering

 Leading edge erosion has   developed into a significant issue for the wind industry. Raindrops, hailstones, and other particles impacting the leading edges of the blades cause material to be removed. This leaves a roughened blade surface, which degrades the aerodynamic performance of the blade, and hence its power production. The problem appears to be accelerated offshore due to high blade tip speeds and harsher operation environments. Viscoelastic Leading Edge Protection (LEP) systems are applied to the leading edge of blade to mitigate the onset of erosion. However, there is currently no LEP that lasts the lifetime of the turbine and regular repair is required. It is estimated that the issue costs £1.3m per turbine over its lifetime [X]. To support the development of improved LEP systems, the WBRH has worked with industrial LEP companies to investigate two key areas: (i) an understanding of the viscoelasticity of LEP systems and (ii) mechanisms to test and predict LEP performance. On the former, the WBRH has developed bespoke techniques to understand the drivers of LEP erosion performance by expanding knowledge in strain and frequency dependent behaviour and measurement techniques, including dynamic mechanical thermal analysis, acoustic measurement, and nano indentation. On the latter, a prediction model to relate an LEP’s test performance to its in-situ performance has been developed. This included an exploration of current erosion testing mechanisms to enhance their ability to realistically evaluate performance and the first characterisation of a wind turbine’s erosion environment. Together these two pieces of research have developed significant understanding of the drivers of erosion and important material properties, providing the wind industry with tools to further develop LEP systems and combat the important challenge of leading edge erosion. 

Modular blades: 

Photo of Alex Moss
by Alex Moss

The overall aim of this work is to enable faster,  cheaper, and easier production of wind turbine blades, which will help to reduce global dependence on fossil fuels. This is achieved through additive manufacturing, which will be used to build the internal structure of the blade. Acting as the composite layup surface, this would replace the costly and energy intensive steel-backed composite moulds currently used. Introducing automation into production process could lead to the creation of an assembly line, helping to make the 3 blades per day required to hit 2030 wind energy targets. To design these novel blade structures, topology optimisation is used to find the lightest possible configuration, reducing material use and energy. The wider industry is beginning to use recyclable materials to cut down on landfill waste at the end of life. The printed material takes this one step further, using recycled chopped carbon and glass fibre inside a recyclable resin. The printed material also replaces the balsa wood cores, into which the resin leaks during infusion which is wasted material and makes the balsa unrecyclable.  

Advanced numerical models:

Photo of Sander Van den Broek
by Sander Van den Broek

As blades increase in length, they become increasingly difficult to structurally model. Traditional approaches using shell elements cannot accurately model the torsional stiffness as failure modes that become more important at larger length scales. At the same time, solid elements found in commercial finite element software are limited to lower-order descriptions of displacement fields. Convergence using lower order solid elements would require an excessive number of elements, becoming computationally prohibitive. Ongoing work at the WBRH is to develop higher-order structural modelling techniques that can simulate the nonlinear stresses and evaluate the stability of large wind turbine blades.