Category: Research

CIMComp Hub Storytelling Workshop Review

Posted on by jo.rich

by Umeir Khan

Creating a compelling and impactful story can be challenging. Fortunately, there are tools at hand to engage our audiences and craft a message that is pitch-perfect.

Following on from the success of prior workshops coordinated by the CIMComp Researcher’s Network, early April saw a fantastic turnout from current PhDs/EngD students for the “Storytelling for Engagement” activity, hosted at the University of Nottingham’s campus, and delivered by material scientist / professional storyteller – Dr Anna Ploszajski.

Many items of consideration were brought up: the type of audience you are presenting to, understanding their motivations and playing with the narrative hooks that drive the dramatic tension in a story. Unsurprisingly, a lot of parallels can be found in our favourite films, the ‘what if?’ that starts the journey for a protagonist to the ‘what if’ that sparks our own research.

Overall, it was a splendid event which helped demystify the route to effective research communication and impact. Highly recommended!

CerTest Independent Advisory Board and Industrial Steering Group Meeting, 17 April 2024 in Southampton

Posted on by jo.rich

On April 17th 2024, the CerTest team met with the Independent Advisory Board (IAB) and the Industrial Steering Group (ISG) for a fantastic day of presenting the project’s research goals and achievements along with in-depth discussions about CerTest methodologies and next steps, including what comes after CerTest . Presentations and posters were made by CerTest researchers and PhD students covering the work going into each of the project’s four research challenges, as well as the interactions and joint activities.

The CerTest team presented a complete vision for the project, and for the first time a holistic depiction of what the CerTest methodology for performance validation and ultimately certification will encompass, and how it is different from the current building block approach. Essentially, a road map towards certification by analysis or digital certification was outlined. The presentations were very well received by the representatives from the IAB and ISG including cross sector industry stakeholder and the funder EPSRC. The day was topped off with an evening dinner reception that concluded a very enjoyable day for all.

A seated audience looking at a presentation screen A seated audience looking at a presentation screen

Mystery of moths’ warning sound production explained in new study

Posted on by jo.rich

The workings of the ultrasonic warning sounds produced by the wings of a species of moth have been revealed by researchers at the University of Bristol.

Bristol Composites Institute (BCI) Academics Prof. Alberto Pirrera and Dr. Rainer Groh, along with Prof. Marc Holderied and Research Associate Dr. Hernaldo Mendoza Nava in Biological Sciences at the University of Bristol have successfully had a paper published in the ‘Proceedings of the National Academy of Sciences’ (PNAS).

The scientists recently discovered that moths of the genus Yponomeuta (so-called ermine moths) have evolved a very special acoustic defence mechanism against their echolocating predators—bats.

Ermine moths produce ultrasonic clicking sounds twice per wingbeat cycle using a minute corrugated membrane in their hindwing. Strikingly, these moths lack hearing organs and are therefore not aware of their unique defence mechanism, nor do they have the capability to control it using muscular action.

In the study, published today in Proceedings of the National Academy of Sciences, an interdisciplinary team of engineers and biologists from Bristol show how individual ridges of a corrugated patch in the hindwings of ermine moths snap-through because of in-flight wing folding. The sudden snap-through of these features vibrates an adjacent membrane, significantly amplifying the strength and direction of the produced sound. Owing to its passive in-flight actuation, this sound-producing organ is known as an ‘aeroelastic tymbal’.

Marc Holderied, Professor of Sensory Biology at the School of Biological Sciences, explained: “Our goal in this research was to understand how the corrugations in these tymbals can buckle and snap through in a choreographed way to produce a chain of broadband clicks. With this study, we unfolded the biomechanics that triggers the buckling sequence and shed light on how the clicking sounds are emitted through tymbal resonance.”

 

The study’s first author, Hernaldo Mendoza Nava, who investigated the mechanics of the aeroelastic tymbal as a PhD student at the EPSRC Centre for Doctoral Training in Advanced Composites for Innovation and Science of the Bristol Composites Institute (BCI), said: “Sound production and radiation is linked to mechanical vibration, for example in the skin of a drum or a loudspeaker.

“In ermine moths, the snap-through buckling events act like drumbeats at the edge of a tymbal drum, exciting a much larger portion of the wing to vibrate and radiate sound. As a result, these millimetre-sized tymbals can produce ultrasounds at the equivalent level of a lively human conversation.”

 

To uncover the mechanics of the aeroelastic tymbal, Hernando combined state-of-the-art techniques from biology and engineering mechanics. The biological characterisation of the wing’s morphology and material properties ultimately led to detailed computer simulations of the snap-through response and sound production that match recorded moth signals in frequency, structure, amplitude, and direction.

Rainer Groh, Senior Lecturer in Digital Engineering of Structures at the BCI added: “The integration of various methods across the sciences with a consistent information flow across discipline boundaries in the spirit of ‘team science’ is what made this study unique and a success. In addition, without the amazing modern capabilities inimaging, data analysis and computation, uncovering the mechanics of this complex biological phenomenon would not have been possible.”

 

The discovery will help researchers understand many other insect species with similar sound production mechanisms, filling a page of anti-bat acoustic defences in the book on the age-old arms race between echolocating bats and their insect prey.

Structural buckling and sound production are rarely studied together, despite being reciprocal phenomena. In addition, buckling occurs as a sudden large deformation which can be attractive as a shape-changing mechanism in the field of morphing structures, such as in the aerospace industry, where engineers are looking to optimise the aerodynamic performance of wings.

Alberto Pirrera, Professor of Nonlinear Structural Mechanics at the BCI, concluded: “In the realm of engineering design, nonlinear elastic responses, such as buckling and snap-through instabilities, have traditionally been perceived as failure modes to be avoided. In our research, we have been advocating a paradigm shift and have demonstrated that buckling events can be strategically leveraged to imbue structures with smart functionality or enhanced mass-efficiency. Yponomeuta’s aeroelastic tymbal embodies the concept of beneficial nonlinearity.

“The natural world, once again, serves as a source of inspiration.”

 

 

The research team anticipates that through bioinspiration, aeroelastic tymbals will encourage novel developments in the context of morphing structures, acoustic structural monitoring and soft robotics.

 

Paper:

Buckling-induced sound production in the aeroelastic tymbals of Yponomeuta (pnas.org) by Hernaldo Mendoza Nava, Marc Holderied, Alberto Pirrera and Rainer Groh in Proceedings of the National Academy of Sciences of the USA.

 

You can also list to episode  ‘This week in science: moths’ anti-bat signal, fish who count and GMO crops at home : NPR‘ published February 8 2024 on the NPR Podcast.

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

Posted on by jo.rich

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. 

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

Posted on by jo.rich

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

Posted on by jo.rich

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)

2023 BCI & NCC Annual Conference

Posted on by jo.rich

The Bristol Composites Institute (BCI) and National Composites Centre (NNC) recently hosted their joint annual conference at Wills Hall Conference Centre in Bristol. If you missed out this year, then a recording of the BCI & NCC introductions, Technical Presentations and the Keynote Lecture are available to view on the BCI Youtube Channel.

Matt Scott from National Composites Centre presenting in front of a screen

The focus of the event was on future applications of composite materials, through industry focussed innovation. We were at capacity with nearly 200 attendees, for an array of technical presentations and thought-provoking discussions. There were presentations from BCI and NCC on Sustainable and Natural Materials, CMC’s for High Temperature Applications and Future Structures – how composites can be redesigned to unlock function and performance.

This was followed by an insightful keynote lecture from Alison Green at Vertical Aerospace titled “How composites will help disrupt the future of air travel”.

A seated audience watching a presentation

We finished the day with a panel session which focused on 4 key areas:

  • Challenges for new sustainable materials
  • How to create a level playing field for LCA of materials?
  • UK competitiveness in new materials
  • Reduction of product development costs

 

 

The panel session was chaired by Mike Hinton of the High Value Manufacturing Catapult, with an expert panel sharing their knowledge; Faye Smith (Avalon Consultancy Services), Jon Meegan (Solvay), Fabrizio Scarpa (BCI), Marcus Walls-Bruck (NCC), Lourens Blok (Lineat), Jonathan Fuller (NCC) and Alison Green (Vertical Aerospace).

A seated panel session facing an audience