HyPower Bristol’s development of a 5kN bipropellant liquid rocket engine and supporting liquid feed system

HyPower Bristol are a team of students from the BristolSEDS society, working on building and launching cutting edge student sounding rockets since 2020. Last year we entered the 2023 EUROC competition, which is held in annually in Ponte de Sor, Portugal. This Europe wide competition is hosted by the Portuguese Space Agency and brings the best rocketry teams from universities across the continent, including Delft, TUM and of course, University of Bristol. Our compact team managed to achieve 3rd place in the ‘Off the shelf’ solid motor category last year and have since built towards even greater engineering challenges for this year’s EUROC 2024 competition.

Following conversations with the Portuguese Space Agency last year, we have embarked on the ambitious development of a 5kN bipropellant liquid rocket engine and supporting liquid feed system. This engine will run on with isopropanol fuel and nitrous oxide oxidiser, exhausting the 19L of propellant tanks in under 6s.

To meet our goals of flying this liquid engine at the EUROC 24 competition, we have had to flight test many new aspects of our design throughout the year such as control electronics and software. To easily make these flight tests, we started the year by manufacturing a half size sized “sub scale” rocket which uses a hybrid metallic/ composite structure.

In this design, the lower carbon section is made up of removeable panels which bolt into an underlying metallic frame, facilitating quick access to the electronics under test. The carbon parts are made with a wet layup of Prime 37 and 600gsm triaxial carbon, and the glass parts used biaxial plane weave E-glass. The parts were laid on to aluminium tools and cured under vacuum. The laminates have not been optimised for mass and are quasi-isotropic, as the requirements of the test vehicle call for high reliability and spare thrust budget is available. A focus of the EUROC 2025 programme will be minimisation of mass through an optimised fully composite structure.

The fin section has been designed to be removeable which allows the testing of different fin configurations and adjusts the rocket’s mass distribution. For this part, individual fins were first laid up using 3d printed aerofoil moulds, before being aligned and bonded to a section of carbon tube. Further uni-directional carbon was then applied between the tips of adjacent fins to reinforce the bonded joints and suppress aeroelastic fin “flutter” which is a common failure mode for similar unstiffened fins. The structure has been flown twice this year and has proven very reliable: this was exemplified by a failed parachute deployment and subsequent drop from 250m which only required the replacement of a single fin. These launches have demonstrated the many systems including robust telemetry and our inflight deployed air brakes which will allow us to control to a specified altitude in Portugal.

The launches have also been key to developing our test procedures and checklists for the future flights. Depending on funding availability, we would like to conduct a final set of launches in September to trial additional functionality with our custom electronics.

Following our work on the test vehicle, we have begun manufacturing the full-size entry for Portugal. The airframe design will be similar to the subscale, with an internal metallic structure to mount valves and electronics, and a stressed carbon panel skin which prevents buckling but still allows quick access to the propulsion system. Our initial design held propellant in commercially available COPVs, however these were difficult to package and would cause the vehicle to be over 5m long. We have therefore developed an aluminium coaxial propellant tank, which minimises the vehicle length by using the entire cross section to store propellant and passes the inertial and aerodynamic flight loads through the tank wall. Despite the less efficient material, this tank option reduces the total mass by more than 5kg by reducing the vehicle length to 3.5m.

The composite manufacture has begun with experiments using low-cost foam tooling, this has been successful for the panel sections. The next step will be manufacture of tube sections, however the internal surface is more critical for these parts, and we will need to see if we can achieve an adequately flat finish for bonding to the metallic and polymer adapters. We recently received the 3d printed Inconel chamber, and the machined propellant tank components are nearly ready for test.

We have also had the opportunity to work with the AENGM0050 Design, Build, and Test unit this year to develop a highly efficient payload mounting structure. This design has been inspired by sea sponge skeletons found in nature and manufactured with prepreg carbon tape. The structure has been built by the students and successfully tested far in excess of the loads that will be experienced in flight. The structure will support our 1kg stack of 3 cube satellites during flight in Portugal.

Some members of the team have also recently built an entry to the UK high powered rocketry competition which took place in Scotland last year. For this we constructed a simple fibreglass airframe based on tape wrapped glass tubes. This rocket hit its target apogee of 2200m and set a new Bristol speed record of 1030km/h and then safely returned on computer deployed parachutes, winning us the UK title.

Our next steps for this design cycle are to pressure test the propellant tank and perform an integrated hot-fire which will prove the engine, propellant loading system, and remote control system. The team would like to say an enormous thank you to the BCI community for supporting us in our rocket journey so far, and we hope you are as excited as us to see what we manage in Portugal!

If you have any thoughts about our design or perhaps can think of a way to support us, please feel free to reach out to lk2093@bristol.ac.uk and hypowerbristol@gmail.com

Follow our journey here: LinkedIn or Instagram and https://euroc.pt/  to learn more about the EUROC competition.

Lillian, Jacob, and the HyPower Bristol Team.

 

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

Why you should consider the EngD route for your doctorate study…

The Industrial Doctorate Centre in Composites Manufacture (IDC) is pleased to announce that we are seeking high calibre candidates to take up one of five fully funded EngD studentships based at the National Composites Centre (NCC) – the UK’s leading mid-TRL innovation facility in composite materials.

To apply complete and submit this online form and send your CV and transcript of results to Helen.Howard@bristol.ac.uk

Why an EngD?

Patrick Sullivan, an EngD student currently based at the NCC, says

“ The ethos of an EngD is to work in industry as if you are a full time employee, fully embedded in your organisation’s system’s and structures, but to work towards your long term research and academic goal as your thesis approaches. The industry focus is beneficial for steering your research in a meaningful way, allowing greater impact and dissemination of your work. 

The appeal of an EngD is that you stay in the academic loop where innovation rules with the freedom to pursue research topics and work with world leading academics. But you are also driven by the focus of your industrial sponsor and their need to see the impact of the research on live projects. ”

As a successful applicant, you will be based at the National Composites Centre (NCC) and will work on novel, yet industrially focused, cutting-edge research, whilst following a taught programme at University of Bristol. The projects will cover a wide range of NCC’s strategic areas with a focus on using digital manufacturing with composite materials to solve urgent issues towards sustainability.

Financially it makes sense too.

Successful applicants will receive an enhanced tax-free stipend of £23,730 a year, a fee waiver and a generous allowance to support training.

 

Why the EngD works for industry.

The NCC has supported the Industrial Doctorate Centre (IDC) in Composites Manufacture for many years. Matt Scott, Chief Engineer for Capability at NCC, says

“ We find that our deep partnership with the IDC allows us to solve two pressing needs. Firstly, it gives us a mechanism to set motivated and tenacious minds on solving some of the research challenges that a commercial context by itself may not easily allow for. Secondly, it allows us to train the leaders of tomorrow towards an exciting and fulfilling career in the composites sector and beyond. ”

The topics you could be working on.

We are seeking highly motivated and committed individuals with an eye on the future, who are interested in conducting stimulating and essential industrial research and have a passion for finding sustainable solutions in areas such as:

  • Low-carbon concrete.
  • Through-Life Damage and Environmental Assessment.
  • Recycled Fibre/Matrix Interfacial Properties
  • Composite Shielding against Directed Energy Weapons
  • High-Rate Automated Deposition of CFRP for rapid production of aircraft wings.
  • Advanced Tooling for Aerospace Composites
  • Large Scale Rapid Infusion of wings.
  • In-Process Material Inspection and Verification of Aerospace Parts.
  • Digital Passport for Re-Using Aerospace Manufacturing Waste.

For more information about the topics you could be exploring visit our website here.

Professor Janice Barton, Director of the IDC, says;

“ If you are interested in studying for a doctorate at University of Bristol, being involved in the activities of Bristol Composites Institute and have a passion to explore sustainable composites solutions to address NetZero challenges then please consider applying to be part of our inclusive and dynamic programme in Composites Engineering. ”

What you need to bring.

Applicants must hold/achieve a minimum of a 2:1 MEng or merit at Masters level or equivalent in engineering, physics or chemistry. Applicants without a master’s qualification may be considered on an exceptional basis, provided they hold a first-class undergraduate degree. Please note, acceptance will also depend on evidence of readiness to pursue a research degree and performance at interview.

Due to visa restrictions these posts are available to Home/EU (UK settled status) with permanent UK residency.

To apply complete this online form and send your CV and transcript of results to Helen.Howard@bristol.ac.uk

If you have any further questions about our programme, or if you would like to have an informal chat with Professor Barton or a current EngD student, please do get in touch by e-mail.

Helen Howard, IDC Manager Helen.Howard@bristol.ac.uk

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. 

Composites for Hydrogen Storage for Green Aviation

by Valeska Ting v.ting@bristol.ac.uk; James Griffith james.griffith@bristol.ac.uk; Charlie Brewster c.d.brewster@bristol.ac.uk; Lui Terry lt7006@bristol.ac.uk  

 

Of all of the modes of transportation that we need to decarbonize, air travel is perhaps the most challenging. In contrast to road or marine transport, which can realistically be delivered with battery or hybrid technologies, the sheer weight of even the best available batteries makes long-haul air travel (such as is needed to maintain our current levels of international mobility) prohibitive. Hydrogen is an extremely light, yet supremely energy-dense energy vector. It contains three times more energy per kilogram than jet fuel, which is why hydrogen is traditionally used as rocket fuel.   

Companies like Airbus are currently developing commercial zero-emission aircraft powered by hydrogen. A key challenge for the use of hydrogen is that it is a gas at room temperature, requiring use of very low temperatures and specialist infrastructure to allow its storage in a more convenient liquid form. To deliver this disruptive technology Airbus are undertaking a radical redesign of their future fleet to enable the use of liquid hydrogen fuel tanks[5].

A jet flying in the sky

In its liquid form, hydrogen needs to be stored at –253oC. At these temperatures, traditional polymer matrices are susceptible to microcracking due to the build-up of thermally induced residual stresses. Research at the Bristol Composites Institute at the University of Bristol is looking at how we can develop new materials to produce tough, microcrack resistant matrices for lightweight composite liquid hydrogen storage tanks. 

We are also looking at the use of smart composites involving nanoporous materials – materials that behave like molecular sponges to spontaneously adsorb and store hydrogen at high densities– for onboard hydrogen storage for future aircraft designs. Hydrogen adheres to the surface of these materials; more surface area equals more hydrogen. One gram of our materials has more surface area than 5 tennis courts, with microscopic pores less than 1 billionth of a meter in diameter. These properties allow us to store hydrogen at densities hundreds of times greater than bulk hydrogen under the same conditions. Whilst simultaneously improving the conditions currently needed for onboard hydrogen storage. Our research looks to improve this by tailoring the composition of these materials to store even greater quantities of hydrogen beyond the densities dictated by surface area.  

With hydrogen quickly becoming recognised around the world as the aviation fuel of the future, France and Germany are investing billions in ambitious plans for hydrogen-powered passenger aircraft. To keep pace with the development of new aircraft by industry, there is a parallel need for rapid investment into refuelling infrastructure at international airports to allow storage and delivery of the liquid hydrogen fuel. Urgent investment to also upgrade the hydrogen supply chain is imperative. The UK Government’s announcement of new investment in wind turbines and offshore renewables will certainly boost the UK’s ability to generate sustainable hydrogen fuel and presents additional opportunities for new industries and markets.  

It seems industry is finally ready to take the leap away from its reliance on fossil fuel to more sustainable technologies. Decisive action and public investment into upgrading our hydrogen infrastructure will allow us to realise the many benefits of this and will make sure the UK remains competitive in this low-carbon future.

 

 

Images and permissions available from: 
https://www.airbus.com/search.image.html?q=&lang=en&newsroom=true#searchresult-image-all-22  

References:  

[1] Hydrogen-powered aviation – A fact-based study of hydrogen technology, economics, and climate impact by 2050 https://www.fch.europa.eu/sites/default/files/FCH%20Docs/20200507_Hydrogen%20Powered%20Aviation%20report_FINAL%
20web%20%28ID%208706035%29.pdf
[2] Liquid Hydrogen–the Fuel of Choice for Space Exploration https://www.nasa.gov/content/liquid-hydrogen-the-fuel-of-choice-for-space-exploration 
[3] Airbus looks to the future with hydrogen planes
https://www.bbc.co.uk/news/business-54242176 
[4] Liquid Hydrogen Delivery
https://www.energy.gov/eere/fuelcells/liquid-hydrogen-delivery 
[5] Airbus reveals new zero-emission concept aircraft https://www.airbus.com/newsroom/press-releases/en/2020/09/airbus-reveals-new-zeroemission-concept-aircraft.html 
[6] Bristol Composites Institute
http://www.bristol.ac.uk/composites/ 
[7] Nanocage aims to trap and release hydrogen on demand https://www.theengineer.co.uk/nanocage-hydrogen-gas/ 
[8] Engineering porous materials
https://www.youtube.com/watch?v=TNqLeO61huM 
[9] France bets on green plane in package to ‘save’ aerospace sector https://uk.reuters.com/article/us-health-coronavirus-france-aerospace/france-bets-on-green-plane-in-package-to-save-aerospace-sector-idUKKBN23G0TB 
[10] Germany plans to promote ‘green’ hydrogen with €7 billion https://www.euractiv.com/section/energy/news/germany-plans-to-promote-green-hydrogen-with-e7-billion/ 
[11] EU Hydrogen Roadmap https://www.fch.europa.eu/sites/default/files/Hydrogen%20Roadmap%20Europe_Report.pdf 
[12] Boris Johnson: Wind farms could power every home by 2030 https://www.bbc.co.uk/news/uk-politics-54421489  

Natural Fibre Composites Research

Testing the Mechanical Performance of Nature Fibre Composites.

Head shot of Owen Tyley by Owen Tyley owen.tyley.2019@bristol.ac.uk; Tobias Laux tobi.laux@bristol.ac.uk; Neha Chandarana neha.chandarana@bristol.ac.uk 

Manufacturers are increasingly looking to develop new natural fibre composites (NFCs) to lower the environmental impact of structures such as wind turbine blades and automotive panelling. For these to be brought to market, their mechanical performance must be understood throughout their operating temperature range. This is ordinarily conducted using strain gauges, though the cost of purchasing and installing strain gauges makes this a relatively expensive undertaking. By contrast, digital image correlation (DIC) is an optically-based imaging technique which can determine the strains on an object such as a standardised testing coupon, at much lower cost. However, the reliability of DIC for composite coupons at elevated temperatures is not well-understood. 

Black and white photo of natural fibre composites

As part of a summer internship project supported by the Henry Royce Institute for Advanced Materials, the tensile moduli of flax- and carbon-fibre reinforced polymers using both DIC and strain gauges at temperatures up to 120°C were compared. Preliminary results suggest that the modulus as determined through DIC is the same as for strain gauges, but with greater uncertainties. It is therefore suggested that DIC could be a suitable method for determining the mechanical properties of NFCs for non-safety-critical applications, and as part of early-stage research and development for new natural-fibre composites. 

 

Flax: A sustainable alternative to glass fibres in wind turbines?

 

 

 

by Abdirahman Sheik Hassan a.sh.2019@bristol.ac.ukNeha Chandarana neha.chandarana@bristol.ac.uk ; Terence Macquart

Flax-fibre composites have been widely praised as a high-performance sustainable alternative to synthetic fibres in the composites industry. However, as with many natural fibre composites, the mechanical properties (strength, stiffness) of flax-fibre composites do not match up to their synthetic counterparts. This study assesses the suitability of flax-fibre reinforced composites as a replacement for glass-fibre composites in the context of a wind turbine blade using a life cycle engineering approach.Research on a computer screen Finite element analysis (FEA) was used to determine the design alterations required for comparable performance, followed by a cradle-to-grave life cycle assessment to ascertain the subsequent environmental impact of these alterations. The preliminary results show a significantly greater volume of material is required in a flax-fibre blade to match reserve factor and deflection requirements; however, these models do show reduced environmental impact compared with the glass-fibre composite blades. End-of-life options assessed include landfill and incineration, with and without energy reclamation. 

 

Amphiphilic Cellulous for Emulsion Stabilisation and Thermoplastic Composites.

Headshot of Amaka Onyianta Headshot of Steve Eichhorn by Amaka Onyianta a.j.onyianta@bristol.ac.uk; Steve Eichhorn s.j.eichhorn@bristol.ac.uk

Biobased polymers, commonly referred to as bioplastics, are made from plant or other biological material instead of petroleum. They, therefore, present opportunities for the development of sustainable plastics from a wide range of pre-cursors including corn, vegetable oil and cellulose. Cellulose, the most abundant polymer on earth, is also renewable material available from vast resources such as wood, plant, bacteria and even sea animal tunicates. Considerable research efforts have been put into developing cellulose-based biopolymers. However, despite all its advantages, cellulose due to its hydrophilic (water-loving) nature presents a significant challenge with respect to blending with other polymers which are often hydrophobic (water-repelling).  

Diagram showing amphiphilic cellulose coated polypropylene composites

To address this challenge, our group is exploring surface modification of cellulose to make it hydrophobic. One such modification we have investigated results in a material that is not only hydrophobic, but largely retains the inherent hydrophilicity of cellulose, leading to an all-new class of material: amphiphilic cellulose. Due to this amphiphilic nature, the cellulose can stabilise oil-in-water emulsions, making it attractive for various applications including in the personal care products sector where consumer desire for nature-based products is increasingly driving demand.    

It is also recognised that while material sources can be sustainable, processing techniques also need to be sustainable for this credential to hold for the final product. Work within our group is therefore also looking into aqueous processing of amphiphilic cellulose with thermoplastics to yield biobased sustainable composite materials with improved tensile modulus. Moreover, the melting profile of the thermoplastic is not affected by the process, neither is a pre-step of compounding needed as seen in the traditional process for incorporation of fillers in thermoplastic composites.  

BCI Attends ECCM20

We are delighted to announce that a large team from the Bristol Composites Institute (BCI)  showcased their achievements and research at ECCM 20 (the 20th European Conference on Composite Materials) in Lausanne, Switzerland from 26th to 30th June 2022. ECCM is the main European forum for knowledge exchange on recent accomplishments and future trends, bringing together people from academia and industry with a mutual interest in composite materials.

UoB at EMCC20 event

This year’s conference was focused on sustainability which is a prominent aspect of composites for BCI with the title “Composites meet Sustainability”. An impressive line up of academics, researchers and PhD students highlighted our commitment toward sustainability across a range of activities spanning academic research, industrial collaborations and education programmes with more than forty presentations. Professor Ivana Partridge started the conference with her invited keynote lecture covering her eminent and ground breaking work with the title “Toughening approaches in composites – a perspective”. Several researchers showcased their accomplishments on the HiPerDiF (high performance discontinuous fibre) technology, invented at the University of Bristol, which produces highly aligned discontinuous fibre composites to address the issues of the composite industry – manufacturing and recycling.

Our Industrial Doctorate Centre (IDC) in Composites Manufacture marked the achievements within two special sessions and a dedicated poster session, organised by Professor Janice Barton that took place on 28th July. The special sessions featured twelve papers, presented by the IDC EngD students, on a wide range of processes covering braiding, tape and fibre placement, modular infusion, over-moulding, application of sustainable and novel materials; development of modelling procedures; and performance investigations. We are also proud to announce that one IDC student Dave Langston won the conference poster prize – sponsored by OREC.

BCI Group at EMCC20