Author: jo.rich

Real-time Quality Control in Automated Fibre Placement using Artificial Intelligence 

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by Gabriel Burke, Duc H. Nguyen, Iryna Tretiak.

The growing demand for ever more cost and labour effective production of large, lightweight, and geometrically complex composite structures has led to the replacement of traditional manufacturing processes, such as hand lay-up and vacuum bagging, with automated processes such and Automated Fibre Placement (AFP). The AFP method uses robotic arms to deposit layers of carbon fibre reinforced composites (CFRP) onto bespoke moulds. This process can create complex shapes at high speed. However, manufacturing-induced defects are inevitable during AFP. This degrades the strength of the final parts and creates a major waste problem, with defective parts discarded in some cases. While automation of composite manufacturing processes has been successfully industrialised, inspection is still largely a manual process.

As we move towards Industry 4.0, it is possible to optimise inspection during the AFP manufacturing process. One option of improving inspection is to implement artificial intelligence.

Our research team at the Bristol Composites Institute (BCI) has successfully designed and implemented a system that performs real-time defect detection and classification during the AFP process, providing information on the location and type of defects in the tape almost instantly after it has occurred.

The developed system is built upon a convolutional neural network (CNN), which uses deep learning techniques to detect defects based on input data images. These images were generated using data collected from a Micro-Epsilon profilometry sensor attached to the AFP gantry. This system can correctly identify and differentiate between three defects (fold, twist, and pucker) and does so in real-time using a three-stage algorithm:

1. Live data collection and pre-processing;

2. A sampling and image optimisation algorithm to produce a moving window of input images for the CNN;

3. Defect detection/classification using the CNN.

Due to this modular design, it is possible to modify each stage to fit the needs of other AFP applications. For example, the CNN can be retrained to ‘look’ for other defects, or the sampler could be modified to collect images at a different frequency based on the scale of the part being manufactured.

This novel inspection technique provides great potential to improve efficiency and reduce waste in composites manufacturing.

 

Following the success of the initial proof-of-concept phase, the team is looking to upscale the current prototype to meet the speed and robustness requirements of operational systems in industry. 

BCI Alumni Q&A: Usman Sikander, KTP Associate, TRB Lightweight Structures

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Why did you choose the Bristol Composites Institute for your studies?
I first learned about the Bristol Composites Institute during my master’s research in my home country by exploring various papers that discussed composite materials from various angles. My interest at the time was understanding the fibre/resin interfaces, particularly from a mechanical standpoint. Subsequently, I secured a fully funded PhD scholarship, bringing me to BCI, and the rest is history!

What research area did you specialise in whilst you were here?
I focused on customizing the surfaces of polymeric fibres using diverse plasma techniques. The research initiative concentrated on micro/nano-scale modifications to the fibre surfaces, investigating their influence on adhesion at both micro and macro levels, as well as their wetting characteristics with thermosetting matrices. The fibres employed in the study had inert surfaces, causing issues such as delamination, inadequate adhesion properties, and suboptimal wetting characteristics with thermoset matrices in the composite materials. The aim was to enhance the adhesion and wetting properties of these fibres.

 

After leaving the BCI where did you go?
I moved to Huntingdon, Cambridgeshire after graduating to take up the role of Knowledge Transfer Partnership (KTP) Associate. The role is a three-way collaboration between the University of Bristol, industrial partner and UK Research and Innovate (UKRI).

 

What are you currently working on and what do your future plans look like?
I am working on developing novel and bio-derived resin systems for various composite applications, specifically focusing on the e-mobility market. Sustainability is the key element in this development program encompassing the development of materials and methods with low environmental burden and the transfer of knowledge from academia to industry.

 

How did the BCI prepare you for work outside of academia?
The connections I made as a student at BCI were great. They taught me a lot about how research is done in collaboration with industry, especially since my PhD was co-funded by an industrial partner (DSM Dyneema®, now Avient). Working with a mix of scientists and engineers from different parts of the world helped me learn and improve my soft skills and technical abilities. It also gave me a chance to get better at communicating.

Alumni Q&A: Eric Eckstein, Structures Engineer, Blue Origin

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Why did you choose the Bristol Composites Institute for your studies?
It was a confluence of a few factors.  My now-wife, then-girlfriend, Ariel, chose to pursue a higher degree at the Courtould Institute of Art in London.  Meanwhile, I had been fortunate enough to write and receive a grant to study thermally-actuated morphing structures from the European Office of Air Force Research and Development.  I could take myself and this grant to any European university, but it was the world-renown expertise of Drs. Weaver and Pirrera, and their warm invitation, that focused my attention on Bristol.   

I recall my first visit to the UK, on summer scouting holiday.  I borrowed Ariel’s old commuter bike from her East end flat and set off for Paddington, and not long after found myself cranking with all my might up the steep hills that led to the Queen’s building.  After a quick breather, and a warm welcome from Jo Brooks and Dr. Weaver, it was off to see the laboratory facilities.  I was impressed.  Never before, and never since, have I experienced a lab in which the researcher was so well equipped to conduct their work unhindered.  There was most everything one needed to fabricate, test, inspect, measure, and generally get into the right kind of trouble that breeds discovery.  Best of all, the kit was all shared, and no political manoeuvring and horse-trading was required to use some instrument that technically might have been owned by someone else’s professor.  (You folks don’t know how good you have it!)

Finally, it was Bristol, the wonderful city, that cemented my decision.  There will always be a place in my heart for the city that I called home for six wonderful years of a young American’s adventure abroad. 

What research area did you specialise in whilst you were here?
My research aimed to create composite structures which changed shape in response to temperature change.  But unlike the simple bimetal strips that make your meat thermometer dial spin around, I wanted to have these structures be inert to temperature change for some prescribed temperature change, and then suddenly snap into their new shape at a specified triggering temperature.  t’s a bit like trying to combine the classic bitmetal strip with a bistable snap-bracelet.  That nonlinearity was needed to make them useful for gas turbine cooling control and other passive control applications.  

It was easy to make something bistable, but much harder to get the plate or whatnot to pop into it’s new shape due to temperature change alone.  We cracked the problem by laminating parallel UD plies against a high-expansion metal like aluminium, and then curing the laminate to a pre-curved shape.  I’ll never forget the feeling of “we’ve done it!” when we heard the plate go “poing!” all on it’s own, as it snapped into it’s new shape as we heated it in the oven.  An entertaining activity was to take the warm plate from the oven, slip it under a hapless researcher’s desk, ideally seeking out a jumpy fellow deeply engrossed in work.  The plate would cool off and go “poing” again, to the delight of anyone observing the little prank. 

After leaving the BCI where did you go?
I was lucky enough to get my CV to Blue Origin, just as they were starting on the design of what would become their New Glenn orbital launch vehicle.  I was hired as a structural design engineer, and had a small hand in many of the composite and metallic structures on the 2nd stage and payload fairing.  As I tell my nieces and nephews when they ask what it is that I really do, “I draw pictures of rockets and then we go build them!” 

What are you currently working on and what do your future plans look like?
I’m currently on a great team working out the best structure and propellant tank architecture of a follow-on upgrade to the New Glenn launch system.  I’m also a new dad, and my biggest future plan is to have as much fun as I can making my kid’s life awesome.    

How did the BCI prepare you for work outside of academia?
Like any good PhD program, BCI, or DTC as it was called then, gave me great resources and great independence.  It was clear that the onus was on me, and me alone, to define what I wanted to do, and drive my own work forward.  I think if I had missed out on this formative experience, I might have never discovered some of the career-forming tricks that brought me to where I am.  My favourite:  Focus your best efforts on what you’re most passionate about, and eventually you’ll find people who pay you for it. Also known as, “The harder you try, the luckier you get.” 

Alumni Q&A: Callum Branfoot, Research Engineer, NCC

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Why did you choose the Bristol Composites Institute for your studies?
I chose to study at BCI for a number of reasons. When I was reaching the end of my MSci degree I was really unsure of what I wanted to do but I knew that I wanted to pursue a PhD, that led to me having a scattershot approach in applying to various CDTs including one within the School of Chemistry (where I did my undergrad degree) and one across the road, what was then called the ACCIS CDT. What decided it for me was the desire to work in a more applied area than the highly academic chemistry I was used to, and if I am being completely honest… the reverse psychology Paul Weaver (the then head of the CDT) used on me in my interview— “We’re going to make you an offer, but I don’t think you’re going to accept it”—master tactics from the former used car salesman. 

What research area did you specialise in whilst you were here?
I continued to work in the synthetic chemistry building through large parts of my PhD, trying to make new molecules to build vitrimers and covalent adaptable networks (CANs)—in short, functional (healable/recyclable) composite materials. 

 After leaving the BCI where did you go?
After finishing my PhD, I did a year and half post-doc-ing in the RR UTC with Ian Hamerton as my line manager. Then after 9.5 years of working at UoB I decided to move on… and work for a UoB subsidiary, the BCI finishing school that is the NCC. 

What are you currently working on and what do your future plans look like?
I now work within the Materials Science team at the NCC, working largely on sustainability projects e.g. wind blade recycling, hydrogen tank recycling, sustainable manufacturing consumables, biomaterials, and various other bits and pieces! 

How did the BCI prepare you for work outside of academia?
Unsurprisingly given my current place of work, the BCI was the perfect foundation for the composite materials research I am doing now. By working between the School of Chemistry and BCI, I got plenty of exposure to various ways of working. Plenty of practice in presenting, report writing, self management etc. Importantly, the exposure to various courses and people of various cultures in the BCI helped strengthen the soft skills that are more acutely important in industry. 

Industrial Doctorate Centre in Composites Manufacture: Showcase 2023

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The Industrial Doctorate Centre welcomed over 40 guests to the annual Showcase event, on the 19th September 2023, held at the Watershed in Bristol. The event was followed by a gala dinner at Bristol Harbour Hotel.

The Industrial Doctorate Centre in Composites Manufacture has now reached its 10th year, and over this time, 31 students have graduated with an EngD in Composites Manufacture. The day before the event we welcomed five new students to the IDC, bringing the total number of students currently enrolled to 20. The new students were excited to attend the Showcase along with existing IDC students, alumni, academic and industrial supervisors, and joined by a group specially invited  VIP guests, with strong connections to the UK composites sector. It was a great opportunity for students to present their research work to a wider audience and network within the industry.

The day consisted of 3 oral presentations sessions and a quick-fire poster session all chaired by the IDC alumni. The presentations from our students ranged from topics in advanced manufacturing techniques, new approaches to testing wind turbine blades, process simulation and effect of cryogenic exposure on composites. A focus of the showcase was sustainability, this was brought in to context in a fantastic keynote speech from Dr Ffion Rodes. One of the ambitions for the IDC is for our students to create their own spinouts and companies. Dr Tomasz Garstka a PhD alumni from Bristol Composites Institute has done just that creating his company LMAT. Tomasz gave an excellent keynote presentation  on how he turned his academic research into a commercial tool for composite tooling.

 

The Showcase ended with a very lively panel discussion, chaired by Professor Mike Hinton of the High Value Manufacturing Catapult. The panel comprised  Dr Anna Scott Magma Global; Dr Petar Zivkovic Airbus; Dr Peter Giddings NCC; Dr Faye Smith, Avalon Consultancy; Professor Paul Hogg, Royal Holloway University of London; Janet Mitchell, MC2Consultants.

The panel were asked to discuss how can industrially-based doctoral research help unlock the potential of composites in achieving a Net Zero? The topics discussed included: Understanding better how digital technologies can help accelerate our learning; start thinking of composites as an enabler to protect our way of life by integrating sustainability at the design stage, creating a template for LCA that can be used in all projects; extended in-service life of composites and life extension programmes; smarter testing to reduce waste and move to virtual tests for certification; take steps to eliminate trial and error approaches in manufacturing; move away from the driven by rate approach.

The event was a great success with engaging discussions throughout the day carrying on into the evening at the reception and the gala dinner.

Professor Janice Barton, Director of the IDC was delighted with the day and said “It was fantastic to see our students present their work with confidence and realising they are making a significant difference to their sponsoring companies and to wider society”.

Balancing Environmental and Socioeconomic Sustainability: A Case Study on Heat Pumps and the Path to Net Zero for Engineering Education

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We recently published a case study on the feasibility of heat pumps to reach net zero in the Engineering Professor’s Council (EPC) ethics toolkit, which is available under a CC BY-SA 4.0 license.1 The EPC is a representative body that provides a range of toolkits with resources designed to help educators and trainers integrate aspects including sustainability, ethics, and enterprise into teaching.  

Engineering is key to technological, economic, and societal progress and plays a vital role in moving towards a sustainable future. We have a significant challenge in engineering education: the tendency to view engineering as a purely technical discipline within an apolitical and acultural bubble. However, collaborations involving multiple stakeholders – industry, governments, consumers – are vital to drive change and achieve effective sustainable development by setting policies and incentives that encourage growth and adoption of low-impact technologies. It is important our engineers of the future are aware of our wider professional responsibilities including the social, economic, and cultural context in which they operate.  

Figure 2: AI-generated image illustrating the competition between new and old heating technologies. 2 

This case study was designed to integrate the socioeconomic aspects of sustainability into the engineering challenge of sustainable heating in the UK. Heating is currently responsible for one-third of the UK’s annual carbon footprint, of which 17 % is associated with space heating of homes – comparable to the contribution of petrol and diesel cars.3 Heat pumps are a potential alternative to natural gas boilers, particularly for domestic heating. A heat pump receives heat (from the air, ground, or water) and work (in the form of electricity to a compressor) and then outputs the heat to a hot reservoir (the building you are heating). Worldwide adoption of heat pumps is growing rapidly with the UK Government pledging to increase the number of heat pumps installed to over 600,000 per year by 2028.4 

In this case study students participate in a guided discovery, applying their thermodynamics knowledge alongside discussions to explore the wider themes of sustainability. We have run a version of this study for two-years with undergraduate engineering students as part of their second-year thermodynamics unit. They navigate the need to balance performance, cost, and impact on the consumer. In a memorable part of the session students discover that the lifetime cost of ground-source heat pumps can equal or surpass that of natural gas boilers, due to their high capital cost and the current high cost of energy. This revelation around the increased cost of energy for renewables was a surprise to quite a few students who expected the renewable, greener option to be cheaper and lead to a shift in perspective.  

Prior to this, we ask students to select their preferred heat pump technology (air-source or ground source). The majority select the ground-source heat pump because it has a better thermodynamic performance. The interplay between the improved performance but high capital cost of the ground-source heat pump is used to draw out an important principle: that the ideal or most perfect solution is not always necessary for an effective outcome and that engineers often navigate a balance between performance and cost. Air-source heat pumps, whilst having a lower performance, have a much lower capital cost, installation footprint, and fewer constraints, and so are used quite effectively in practice. Alongside this, the differences in capital investment of these heat pumps allows students to consider how aspects of policy, primarily the importance of bursaries or subsidies, can make renewable technologies more attractive to consumers and increase uptake.  

Figure 1: AI-generated image illustrating the uncertainty around heat pump technology and energy prices. 5 

 

A final key focus of this case study is the social dimension of sustainability, particularly considering consumer needs. Ultimately, even if you offset the capital cost of a heat pump, it is the consumer who will need pay the energy bill and there is growing concern around the affordability of energy. In the UK, electricity costs remain closely tied to natural gas prices and are four-times the cost. Consequently, even though heat pumps can require only up to a quarter of the energy that boilers do for the same heating output, the financial impact on consumers can be comparable or even greater. This is especially important in the context of unstable energy prices and increasing energy poverty. The UK faces a real challenge in the quality of its housing stock, with significant heat loss from homes disproportionately affecting low-income communities.6 Indiscriminately installing heat pumps in properties that have not been properly evaluated or modified can lead to additional financial strains.  

Students really engaged with the different aspects of this case study and feedback has been very positive, which inspired the submission to the EPC ethics toolkit. The real-world applicability, workshop-style lectures, and link to wider global themes were aspects they particularly appreciated. Further case studies are available in the ethics toolkit and the EPC plans to release a sustainability-specific toolkit early next year.  

 

References/Further Reading 

  1. Rowlandson, J. L. Case study: Feasibility of installing heat pumps at scale to reach net zero – Engineering Professors Council. https://epc.ac.uk/toolkit/case-study-feasibility-of-installing-heat-pumps-at-scale-to-reach-net-zero/.
  2. OpenAI. [AI Generated Image] Prompt: Generate an image of a heat pump and gas boiler in a boxing match. ChatGPT [Large Lang. Model. (2023).
  3. Decarbonising heat in homes – Business, Energy and Industrial Strategy Committee. https://publications.parliament.uk/pa/cm5802/cmselect/cmbeis/1038/report.html.
  4. Energy Security Bill factsheet: Low-carbon heat scheme – GOV.UK. https://www.gov.uk/government/publications/energy-security-bill-factsheets/energy-security-bill-factsheet-low-carbon-heat-scheme.
  5. OpenAI. [AI Generated Image] Prompt: An air source heat pump showing the uncertainty around the technology and energy prices. ChatGPT [Large Language Model] at https://chat.openai.com (2023).
  6. Bolton, P., Kennedy, S. & Hinson, S. Fuel poverty in the UK. at https://commonslibrary.parliament.uk/research-briefings/cbp-8730/.

Process Simulation For Reduced-defect Composites

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by Siyuan Chen, Stephen Hallett and Jonathan Belnoue.

 

As the demand for carbon fibre-reinforced composites structures is rapidly growing, the industrial community continues to seek new manufacturing technologies that are low-defect, low-cost, highly efficient and environmental-friendly. Liquid molding is regarded as a cheaper alternative to the traditional prepreg/autoclave approach, however, the latter is often the favoured manufacturing route in the aerospace sector (where safety is paramount) as it allows for the production of better quality parts. One of the many challenges with infusion is the high deformability of the dry fibrous precursor materials that exposes the final structure to risks of defects and part to part variability. If the material and process (including their variabilities) are not controlled to a sufficient level, meeting design tolerances can prove challenging. These risks are traditionally mitigated through “over design” but this reduces a lot of the lightweighting advantages of using composites. 

At BCI, we explore the possibility of achieving reduced-defect forming processes in 3 different ways. Firstly, design tools accounting for manufacturing constraint that are faster than current methods available commercially are being developed [1, 2]. These tools can be used to run moderate numbers (i.e., up to a 100) of simulations and allow to explore the impact of different combination of process control parameters on final part quality. This provide the possibility of optimising the forming process. The robustness of the optimisation is then improved by building Gaussian process (GP) emulator using the dataset produced using our fast simulation tools [3]. These GP emulators can achieve a good accuracy (error < 10%) and model the impact of several input parameters by running only tens of simulations. By introducing dimension reduction and active learning algorithms, the emulators can be expended to much more complex processes with over 10 input parameters [4]. After being trained, the emulators can also provide immediate predictions for final part quality. This open the door for digital twinning where in-process sensing and real-time simulation are combined. Thus, although forming processes can be optimised using deterministic FE simulations, real-world cases are affected by lots of factors such as material and process variability. Some of these variabilities are difficult to avoid but can be measured. Quantifying them (e.g., fibre direction misalignment, tow waviness, etc), a feedback loop whereby real-time simulations are informed by live data of the process and used to adapt the manufacturing condition to improve the final part quality can be set. A forming test cell instrumented with a stereo imaging system is currently being built in our labs. This will be used to construct a prototype digital twin for forming process. 

To summarise, in our vision right first-time design and manufacture of composites can be achieved through a combination of (physics-based) digital design accounting for manufacturing constraints, fast process optimisation using data generated from process models and self-adapting manufacturing hardware controlled through emulators build from process models. 

 

 

[1] Composites: Made Faster – Rapid, physics-based simulation tools for composite manufacture (ukri.org) 

[2] JPH Belnoue, SR Hallett A rapid multi-scale design tool for the prediction of wrinkle defect formation in composite components, Materials & Design, 2020. 

[3] S. Chen, A.J. Thompson, T.J. Dodwell, S.R. Hallett, J.P.-H. Belnoue, Fast optimisation of the formability of dry fabric preforms: A Bayesian approach, Materials & Design, 230:111986, 2023. 

[4] S. Chen, A.J. Thompson, T. J. Dodwell, S.R. Hallett, J. P.-H. Belnoue. A Bayesian surrogate framework for the optimisation of high-dimensional composites forming process. In 5th International Conference on Uncertainty Quantification in Computational Science and Engineering, 2023. 

Moving cheese: energetically efficient shape shifting via embedded actuation

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Compliant materials and slender structures are susceptible to a variety of different instabilities under external stimulus or loading. Traditionally, these instabilities are avoided and classified as failure modes. In recent years, researchers at the BCI have instead attempted to use complex nonlinear behaviour for novel functionality. Simply put, if nonlinearities are understood, then they can be exploited to create well-behaved nonlinear structures. In a recent publication in Physical Review B [1], we employed ‘active modal nudging’ as a novel actuation mechanism for soft robots. In essence, we programmed a soft metamaterial to shape-shift in a rapid and energetically efficient manner by employing embedded actuation to switch between different stable post-buckled modes. 

Our work focused on a latticed metamaterial consisting of an elastomeric matrix with a 3 by 3 square array of circular holes, as shown in Figure 1. We discovered that this metamaterial has three stable post-buckling modes under pure compression, i.e. two sheared modes (sheared left and sheared right) and one symmetric polarised mode. The metamaterial was programmed to favour one of the sheared modes under axial compression via modal nudging [2]. An actuator was then embedded within the central hole to trigger a mode switch between the favoured sheared mode and the polarised mode. We demonstrated that this combination of active and passive nudging is more energetically efficient and requires smaller actuation force than the more widely used global actuation method, as shown in Figure 1(a). By toggling the metamaterial between the sheared and polarised state, we were able to make the metamaterial crawl. The effective locomotion could be employed in soft robotics systems (Figure 2). 

While in this study, we consider a specific type of soft metamaterial and a specific application, the design paradigm introduced can be extended to other scenarios where energetically efficient shape shifting may be beneficial, such as lightweight adaptive wing structures or adaptive façade and ventilation systems for net-zero buildings. 

Figure 1 The actuation force–displacement curve of the lattice metamaterial to achieve a us/L = 0.20 shear displacement amplitude, using: (a) increasing compression from the pre-buckling state; and (b) active nudging from the symmetric deformation mode. 

 

 

Figure 2 (a) A typical actuation cycle for the robot. Yellow and red lines are the reference line indicating the initial and final positions of the right and left edges. The yellow arrows represent the motion of the fixture within the step. (b) The location of the crawling robot in the initial state, after four and eight iterations. A movie of the movement of the demo robot can be found in https://journals.aps.org/prb/supplemental/10.1103/PhysRevB.107.214103/DemoCrawlingRobot.mp4 

 

 

References: 

[1] Shen, J., Garrad, M., Zhang, Q., Leao, O., Pirrera, A., & R. M. J. (2023). Active reconfiguration of multistable metamaterials for linear locomotion. Physical Review B, 107(21), 214103. 

[2] Cox, B. S., Groh, R. M. J., Avitabile, D., & Pirrera, A. (2018). Modal nudging in nonlinear elasticity: tailoring the elastic post-buckling behaviour of engineering structures. Journal of the Mechanics and Physics of Solids, 116, 135-149. 

BCI’s contribution to NCC’s Technology Pull-Through (TPT) programme, 2023-24

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The Bristol Composites Institute (BCI) was involved in both of the projects funded by the NCC in their 2023/24 Technology Pull-Through (TPT) programme, directly aligned with the NCC’s composites strategy. The TPT programme stimulates the transition of suitably mature technologies to industry and is aimed at technologies and methods that are ready to advance from a laboratory environment, typically at Technology Readiness Level (TRL) 3 to 4. One is based on Healable Interfaces, to demonstrate the viability of vitrimer composites for use in repair and end-of-life disassembly, whilst the other is focussed on the standardisation of cryogenic H2 permeability testing in composites, through the development of a test rig to provide testing guidance and data on variance in measurements in this type of testing of composite materials. The Healable Interface work is being conducted by Joe Soltan, working with NCC colleagues, Janice Barton, Dmitry Ivanov and James Kratz, and the Cryogenic Permeability Testing is being conducted by Lui Terry, with NCC colleagues and Valeska Ting. 

Healable Interfaces 

The major challenge in composite repair is that it is costly, a specialist activity, limited by geometry and largely requires cutting of reinforcing fibres, resulting in structural discontinuities. Additionally, in-field repair is typically only possible on a small number of small damage events, and current composite solutions do not offer a viable circular economy approach. The project aims to demonstrate the viability of vitrimer composites for use in repair and end-of-life disassembly. The potential benefits are: 

  • to enable in-field repair, and therefore the extension of service life and the sustainability of composite solutions 
  • to offer the possibility of disassembly through a simple breakdown method at end-of-life, enabling a better circular future for composites 
  • to de-risk composite processing through modular infusion methods 

The project focus is on skin and stiffener interfaces within wind turbine blade structures, although this technology would be relevant to a whole host of other composite applications. Work to date has included a down-selection candidate vitrimer systems, laboratory trials encompassing processability, thermal characterisation and initial mechanical testing to identify an ideal healable interface vitrimer. Future work will develop recommended manufacturing processes and cycles for healable interfaces, and prove the technology for skin/stiffener wind turbine blade structures. Sustainability impacts will provide the projected trade-off point between additional embodied energy and service life extension. At completion, it is envisaged that the application of emerging vitrimer materials in a circular composites industry will have been demonstrated. For further information, please contact Joe Soltan (joe.soltan@bristol.ac.uk) 

Cryogenic Permeability Testing 

The decarbonisation of the aviation industry is contingent on composite materials for cryogenic LH₂ storage. A key issue holding back the technology is that hydrogen permeability through composite materials at cryogenic temperatures is relatively unknown as a result of the scarcity of testing facilities able to reach the cryogenic temperatures (20 K) and a high degree of variability between existing datasets. The barrier is therefore due to a gap in the measurement infrastructure, and a lack of validated measurement standards or guidance on testing cryogenic H₂ permeability in composite materials. This project aims to develop a cryogenic H2 permeability test rig and to provide guidance for cryogenic H₂ permeability testing of composite materials, to help quantify the variance in measurement data that can be expected. The anticipated benefits are: 

  • a reliable and validated cryogenic H₂ permeability method for composite materials 
  • an experimental rig that can be extended in the future to examine interface design between composite and metallic materials 

To date, a cryogenic hydrogen permeation rig (CHyPr) has been designed and built at BCI. The first generation of CHyPr will measure permeability in any solid material between 0 to 80 bar, and from 77 to 293 K. The design and materials selection process for CHyPr however, has accounted for the expansion of the rig to encompass 20-475 K and 0-200 bar in future generations. A reusable permeation cell has been designed and manufactured, capable of measuring both through and lateral permeation of cryogenic hydrogen and now has passed the relevant pressurised equipment safety certification for use. Currently, CHyPr is undergoing calibration and validation of its seals before initial sample testing can begin. This project also involves two other partners, the National Physical Laboratory (NPL) and the University of Southampton, to complete a round-robin benchmarking study of cryogenic hydrogen permeation testing. This aims to determine the current data variance levels between test houses and to isolate the determinant factors in methodology that cause that variance. It is intended to develop guidance in this nascent field on how to better control these variables to ultimately contribute towards a standardised method for cryogenic permeability testing in composite materials. For further information on CHyPr, please contact Dr Lui Terry (lt7006@bristol.ac.uk)

Bringing Composites to Street Youth Work

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Crushing jelly in a mobile van parked on a street in Bristol? Finding the links between silica sea sponges and aeroplanes whilst eating toasties? Playing snap with composite cards?  Not your average day in Bristol Composites Institute… instead a new and enriching experience in the Discover Composites Youth Club on Wheels project!

The Youth Club on Wheels from Young Bristol takes youth work out into numerous hard to reach areas of Bristol.  The skilled youth workers and their large mobile van provide a safe haven for young people to come together, chat and play games. Equipped with wifi, a large screen and a seating area, the van is strategically parked where young people are likely to be – for example across the road from the skatepark, or in the centre of a housing estate.

Children being shown a composites based experiment

NextCOMP have been working with Young Bristol and University of Bristol Public Engagement specialists to co-produce a “workshop in a box” to enthuse and inspire the next generation of composite engineers. Funded by FUTURES, the project is a pilot, and aims to devise a set of activities including guidance documents which can be delivered to young people by non-technical specialists.  The project seeks to strike the balance of designing for accessibility in the environment while still being interesting and different, aiming to spark curiosity in the intended audience. The hope is that the “workshop in a box” activities could be offered to other youth groups such as scouts, guides, after school clubs and even schools.

From the outset, the project team worked to explore and understand some of the challenges of reaching young people in this setting so that activities could be appropriately designed. Numerous logistical challenges of space, transportation, quick access and ease of use are compounded by more challenges of unknown numbers and age range of the young people, potential barriers young people may have to educational activities that might feel too much like school, and inevitable distractions in the environment.

Children taking part in a composites-based experiment

As a result, we developed a range of self-contained 10-15 minute long activities which can be deployed at different points in any order, in the session depending on the circumstances.  The session includes a range of ideas from discussion-based activities through to very practical hands-on manufacturing and testing activities.

The “NextCOMP Crusher” used before in NextCOMPs outreach and engagement delivery has been redesigned for ease of use and transportation and remains a favourite – what’s not to like about making and testing composites made from jelly and pasta? We have designed a set of new “composite cards”, a deck of themed cards using which can be played individually or collectively. In a material show of strength we have created the world’s first “composites tug of war” activity from clay and household objects. Our latest ‘challenge’ is showing the impact strength of chocolate – with the help of our fantastic engineering workshop, we have developed a flat-packed pendulum test to show the benefit of liquorice laces in dark chocolate – what’s not to love about that experiment!

Two sessions have already taken place (Henbury and Speedwell) with two more to go, and we continue to evolve and develop the activities and the guidance documentation as we deliver each session and encounter new challenges and engage with different young people.

Youth Club on Wheels Young Bristol lead Shea Stew said “This is an absolutely awesome project with well thought out activities, fun and to the point.. It makes science more obtainable for these young people.. The young people are getting something different out of it in the sense that they are learning and thinking about materials and the science behind [them].  Feedback from young people has been great, with young people who don’t like school having really enjoyed the activities and reporting back that they have since been paying more attention in science lessons.”

Prof Richard Trask commented, “What an amazing experience… talking about the world around us to highly energised and inquisitive minds. Working with Young Bristol has been inspiring. I have learnt so much and continue to learn. The most important lesson is that there are plenty of budding composite engineers out there, we just need to find the funds and novel ways to get materials and engineering out into the community…”

For more details or any queries about the project contact Jo Gildersleve, NextCOMP Project Manager on jo.gildersleve@bristol.ac.uk