Category: Research

Natural Fibre Composites Research

Posted on by jo.rich

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.uk; Neha 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

Posted on by jo.rich

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

Prestigious Award Won by BCI PhD Student

Posted on by jo.rich

Rafael Ruiz Iglesias, a PhD student in Bristol Composites Institute supervised by Professors Janice Barton and Ole Thomsen, and Dr Geir Olafsson has received the British Society for Strain Measurement (BSSM), Young Stress Analyst prize. The competition, which is sponsored by Airbus, involves writing a 1000 word summary of the applicants project. The project summaries are ranked by a panel of experts in Experimental Mechanics and the top four applicants are invited to present their work at the BSSM Annual Conference which took place in Oxford at St Anne’s college. The competition is open internationally and the other three finalists came from Netherlands, Portugal and UK Industry.

Rafael speaking at conference

Rafa’s presentation entitled “Subsurface Damage Assessment in Composite Laminates Using a Novel Full Field Imaging Technique” which is part CerTest, a 5 year multidisciplinary project, is aligned to the EPSRC funded Programme Grant Certification for Design . Each finalist was allowed 15 minutes for their presentation followed by five minutes of intense questioning; there were over 100 delegates in the audience. Rafa’s presentation was extremely visual and engaging, which the judges appreciated and placed his work first.

The outcome of the competition was announced at the conference gala dinner, which provided a very nice end to the evening with Rafa receiving first prize.

Rafael holding certificate at ceremony meal

Congratulations to Rafa!

 

 

BCI Goes to Glastonbury

Posted on by jo.rich

by Ben Woods. Headshot of Ben Woods

A group of 5 researchers and academics from the BCI and Bristol Department of Aerospace Engineering recently attended the 2022 Glastonbury Festival. Due to pandemic cancellations, this was the first Glastonbury in 3 years and was also the 50th Glastonbury ever, which lined up nicely with the 75th anniversary of the Department of Aerospace Engineering. But while there were quite a few reasons to celebrate – this festival trip was all about outreach. The group spent their days talking to the members of the public about the exciting Green Aviation research going on at Bristol. They set up a marquee in the brand new Science Futures area of the festival and filled it with hands-on technology demonstrators, laser-cut plywood posters, and smiling faces in brightly coloured t-shirts.

A group of people viewing the exhibits in the BCI stand at Glastonbury Festival 2022

The stall featured a series of posters and demos that reflected the diverse, multi-disciplinary work required to make sustainable air transport a reality. It started with a discussion of the multi-disciplinary nature of modern commercial aircraft design, which requires us to improve all aspects of aircraft design.

A table with examples of composite materials on

After this, the ability of composite materials to reduce fuel burn by reducing mass was shown, highlighting both the incredible progress made to date and a range of promising new concepts under development at BCI. Several new morphing wing technologies were then demonstrated, which take inspiration from the way birds continuously adapt and optimize their wings to reduce fuel burn. The next poster highlighted the importance of also reducing non-CO2 emissions, including contrails, NOx, and noise. The final table included a celebration of the 75th anniversary of the Bristol Department of Aerospace Engineering and a wishing tree where the public were invited to share their visions of a more sustainable future for aviation.

The response from the public was fantastic: the stall was busy throughout the duration and hundreds of engaging conversations were had around the challenging topic of how we can make aviation more sustainable. The wide range of people who attend Glastonbury kept things exciting – visitors spanned the gamut from people who hadn’t flown in over a decade because of the climate impact to people who make their living in the aviation industry – with the discussions and messages delivered being adapted accordingly.

The team, led by Dr. Benjamin Woods, camped out behind the stall and had plenty of time to explore the festival and watch acts in the evenings – including electronic music set from a giant fire-breathing, laser-eyed, spider stage, complete with a trapeze artist floating by beneath a giant helium balloon: which is slightly beyond our day-to-day experiences at the Bristol Composites Institute.

A crowd of people at Arcadia 2022

Bristol Composites Institute at ECCM20

Posted on by e.woodland

We are pleased to announce an impressive line up of academics, researchers and PhD students from the Bristol Composites Institute (BCI) who will be presenting their latest work at ECCM 20 (the 20th European Conference on Composite Materials) in Lausanne, Switzerland from 26th to 30th June 2022.

This year’s conference is on the theme of “Composites meet Sustainability” and we will highlight our commitment toward sustainability across a range of activities spanning academic research, industrial collaborations and education programmes.

Our Industrial Doctorate Centre (IDC) in Composites Manufacture is also hosting a special session! The IDC aims to provide the UK composites manufacturing industry with Research Engineers equipped with the necessary advanced technical and leadership skills required for effective adoption of new knowledge and technologies in composites manufacture. For more details and informal discussion please contact Professor Janice Barton (janice.barton@bristol.ac.uk) at booth #6 during the conference. Details of speakers at the session can be found here.

 

Monday 27 June BCI speaker line-up:

Garden 1 / 11:30 – speaker: Nguyen DUC (62031). Title: Real-time Material Measurement for Automated Fibre Placement.

Garden 4 / 11:30 – speaker: Mudan CHEN (61809). Title: Experimental study on the mechanical
behaviour of carbon-fibre Z-pin reinforced curved composite laminates under four-point bending.

Garden 3 / 12:45 – speaker: Ganapathi AMMASAI SENGODAN (61675). Title: Hygro-thermal effects on the translaminar fracture toughness of composite laminates.

Garden 8 / 15:30 – speaker: Athina Kontopoulou (61936). Title: Shape and Size Optimization of Additive Manufactured Lattice Cores with an Evolutionary-Based Approach for High Performance Sandwich Panels.

Garden 4 / 17:00 – speaker Chantal LEWIS (61681). Title: An investigation into the performance is ADFRC produced with HiPerDiF 3G.

Garden 4 / 17:15 – speaker: Gustavo QUINO (61865). Title: Design of a bending experiment for mechanical characterisation of pultruded rods under compression.

Garden 6 / 17:15 – speaker: Roy BULLOCK (61961). Title: Ply Orientation Effects in Multidirectional Carbon/ Epoxy Open-Hole Specimens Subjected to Shear Loading.

Garden 7 / 18:30 – speaker: Xiaoyang SUN (61857). Title: An Experimental Study of Crack Propagation in Stiffened Over-height Compact Tension (SOCT) Specimens.

Garden 6 / 18:45 – speaker: Neha CHANDARANA (62343). Title: Damage characterisation in open-hole composites using acoustic emission and finite element, validated by X-ray CT.

 

Tuesday 28 June BCI speaker line-up:
Garden 10 / 10:30 – speaker: Pedro GALVEZ-HERNANDEZ (61642). Title:  Uncured out-of-autoclave composite prepregs characterizations via deep learning.

Garden 8 / 11:45 – speaker: Tobias LAUX (62344). Title: Hybrid testing for composite substructures.

Keynote Lecture 4 / 14:00 – speaker: Prof. Ivana Partridge. Title: Toughening approaches in composites – a perspective.

Garden 5 / 14:30 – speaker: Aewis HII (62521). Title: Development of a Concurrent Multi-scale Analysis Framework using Shell Elements for the Progressive Failure Analysis of Composites.

Garden 9 / 14:30 – speaker: Joseph SOLTAN (62424). Title: Modular Infusion: Novel Approaches to Segregation and Control of Flow Fronts Within Liquid Resin Moulding.

Garden 9 / 14:45 – speaker: Laura Rhian PICKARD (62302).Title: Manufacturing Advances for Pultruded Rod Based Structural Members and Thick Ply Systems.

Garden 7 / 17:30 – speaker: Antonio MELRO (62388). Title: Modelling delamination resistance of
composite laminates reinforced with novel z-pins through an energy-equivalent bridging map
formulation.

Garden 1 / 18:00 –  speaker: Axel WOWOGO (61636). Title: Influence of Automated Fibre Placement processing parameters on the consolidation of out-of-autoclave prepreg.

Garden 9 / 18:15 – speaker: Janice BARTON (62222). Title: A new test for validating models of lightning strike damage on CFRP laminates.

Garden 10 / 18:15 – speaker: Narongkorn KRAJANGSAWASDI (61680). Title: Highly Aligned Discontinuous Fibre Composite Filaments for Fused Deposition Modelling: Comparison between printed and lay-up open-hole sample.

 

Wednesday 29 June BCI line-up:

Garden 4 / 10:15 – speaker: Ali KANDEMIR (61786). Title: Interfacial shear strength of flax fibre with sustainable matrices.

Garden 4 / 10:30 – speaker: Stephen Hallett (61654). Title: :Novel Z-pin Technologies for Through Thickness Reinforcements.

Garden 5 / 10:30 – speaker Xun WU (61812). Title: Improved Energy Absorption of Novel Hybrid Configurations Under Static Indentation

Garden 7 / 11:45 – speaker: Ram KARTHIK RAMAKRISHNAN (66298). Title: Combined DIC-Infrared thermography for high strain rate testing of composites.

Garden 7 / 14:30 – speaker: Eduardo SANTANA DE VEGA (62438). Title: Improving the mode II delamination bridging performance of fibrous composite Z-pins.

Garden 4 / 17:00 – Ogun YAVUZ BURAK (62348). Title: Tensile characterisation of HiPerDiF PLA/Carbon fibre tape under processing conditions.

Garden 5 / 18:00 – speaker: Anatoly Koptelov (61710). Title: A novel closed-loop testing framework for decoding consolidation deformation mechanisms in manufacturing.

Poster session – David LANGSTON (62605). Title: Torsional Testing of Wind Turbine Blades.

 

Thursday 30 June BCI speaker line-up:

Garden 7 / 08:30 – speaker: Katherine NELMS (62050). Title: Effect of fiber microstructure on kinking in unidirectional fiber reinforced composites imaged in real time under axial compression.

Garden 8 / 08:45 – speaker: Ole THOMSEN (62400). Title: Validation of Composite Aerostructures through Integrated Multi-Scale Modelling and High-Fidelity Substructure Testing Facilitated by Design of Experiments and Bayesian learning.

Campus A / 09:00 – speaker: Rafael Ruiz Iglesias (62267). Title: Surface and subsurface damage assessment of multi[1]directional composite laminates utilizing a full field imaging technique.

Campus A / 09:45 – speaker: Geir Olafsson (61847). Title: Assessment of complex structural scale composite structures by adapting thermoelastic stress analysis for 3D perspective imaging.

 

Don’t miss the latest news and updates from the ECCM Conference via the Bristol Composites Institute Twitter account: ‎@UoBrisComposite!

 

Equity, Diversity and Inclusion Fellowship in Physical Sciences

Posted on by Bristol Composites Institute

The EPSRC recently awarded a large grant (£1.6m) to Professor Steve Eichhorn in the Bristol Composites Institute for a fellowship on “Realising Functional Cellulosic Bio-based Composites”. Fellowships are schemes that allow academics at all levels to focus on research, to make a difference in a field. This fellowship is slightly different, as it includes Equity, Diversity and Inclusion (ED&I). The technical work of the fellowship will focus on biobased and sustainable composites using cellulose towards functional materials. The ED&I aspect of the work will aim to improve the experiences and inclusion of Black students and staff.

ED&I in Engineering

Recent studies have highlighted that fewer than 1% of UK university professors are Black, with previous research showing that there are only 25 Black female professors in the UK.

“For many years during my career, I had been involved in ED&I work. It dawned on me that as a white male within academia not only was I the norm, but I also possessed a lot of privilege that had enabled my career. I also came to realise that I am also part of the problem, with most decision making and shaping of the culture in universities being directed by people who look like me.

The aim of this fellowship is to de-centre that approach, but to also engage more people of all ethnicities to tackle the problem of a lack ED&I of Black and Black heritage staff and students in STEM”, Professor Eichhorn reflects.

For the last 20 years, Professor Eichhorn has been researching the structure-property relationships of cellulose. His research groups have always been diverse, but he has recently realised that certain aspects could still be improved.

“My group over the years has included a wide range of people, with a very good gender balance, but also diverse ethnic, religious, class and cultural backgrounds. This has been a strength to the work we have produced over the last two decades. However, it is evident that people of Black and Black heritage have not been well represented in my group. This is something I have reflected on. This ED&I fellowship gave me a unique opportunity to address this issue and be part of a process of change.”

Cellulosic Bio-based Composites

George Washington Carver (c. 1864 – 1943)

There is a worldwide transition from the use of oil-based to more sustainable materials. This transition is happening due to dwindling oil stocks and a realisation that current levels of the use of this resource are no longer sustainable. However, this is not a new development, as pioneers such as George Washington Carver, working with Henry Ford, developed sustainable and biobased composites in the 1930s. We know from their work that sustainable sources for materials exist in the form of cellulose from plants. This material is a very versatile polymer and is in fact the most utilised material worldwide.

Nature makes use of cellulose to good effect. Being intrinsically strong and stiff means that cellulose fibres, per weight, can compete mechanically with most synthetic alternatives such as glass. In nature’s most prevalent natural composite – wood – cellulose forms the basis of its outstanding structural performance.

All our attempts to replicate the composite performance of wood and plants have fallen short, and this fellowship seeks to address these issues, while also using the intrinsic properties of plant fibres and wood themselves.

Fellowship Research Team

two women in white lab coats in a laboratory smiling at the camera
Dr Anita Etale (left) and Dr Amaka Onyianta (right) in the Bristol Composites Institute research laboratories.

After a search for the right applicants for postdoctoral positions, we were delighted to welcome two researchers – Dr Anita Etale and Dr Amaka Onyianta – with outstanding track records in cellulose research and the lived experience and passion to address ED&I with respect to Black and Black heritage staff and students. They combine these two passions and expertise and are already making an impact in the field.

“I am very glad to be part of this fellowship. This is a rare fellowship that combines my passion for making sustainable materials from nature’s most abundant polymer alongside the opportunity to engage in various ED&I projects that would empower Black and Black heritage staff and students in Bristol and hopefully, the UK at large”, Dr Amaka Onyianta says.

“I believe that representation is key to increasing diversity among the next generation of engineers. Being part of this fellowship gives me the opportunity to play my part in creating a future where ideas are enriched by varied experiences and approaches, and where people have opportunities to pursue the careers they are passionate about, and to contribute solutions to present and future global challenges”, Dr Anita Etale adds.

Find out more

Read more about this fellowship.

For more information, contact Dr Amaka Onyianta, Dr Anita Etale, or Professor Steve Eichhorn.

CerTest – Certification for Design: Reshaping the Testing Pyramid

Posted on by Bristol Composites Institute

One of the larger activities currently happening at the Bristol Composites Institute is CerTest. This EPSRC (UK Engineering and Physical Sciences Research Council) Programme Grant, with £6.9million of funding, started in July 2019 and will run for 5 years.

CerTest is led by Bristol Composites Institute Co-director, Professor Ole Thomsen at the University of Bristol, with academic collaboration partners at the University of Bath, University of Exeter, and University of Southampton.

The aim of the research in this multidisciplinary project is to develop new approaches to enable lighter, more cost and fuel-efficient composite aero-structures. This vision will be realised through four flexible but highly interlinked research challenges:

  1. Multi Scale Performance Modelling
  2. Features and Damage Characterisation
  3. Data-rich High Fidelity Structural Characterisation
  4. Integration and Methodology Validation

The four research challenges will result in a new approach for integrated high-fidelity structural testing and multi-scale statistical modelling through Design of Experiments (DoE) and Bayesian Learning.

The efficient exploitation and optimisation of advanced composite aero-structures is fundamentally prohibited by current test, simulation and certification approaches, and CerTest seeks to break this impasse by holistically addressing the challenges that are preventing step-changes in future engineering design by reshaping the ‘Testing Pyramid’.

The CerTest project is supported by seven key industry partners who provide important steer and valuable market insight along with several funded studentships. Airbus, Rolls Royce, BAE Systems, GKN Aerospace, NCC, the Alan Turing Institute, and CFMS meet with the CerTest team at least twice a year and are keen to see the research succeed.

The project is further supported by an Independent Advisory Board of experts from international and UK based academia, industry and regulators that provide further guidance and support to ensuring CerTest reaches its full potential and realises its goals and objectives.

This is one of the largest collaborations the Bristol Composites Institute has ever undertaken, and a lot of groundwork has gone into supporting the collaboration, flow and sharing of data between the partners. The current CerTest team has 37 members and counting.

group of co-workers standing in front of a building
The CerTest team at an internal meeting held at the National Composites Centre.

Further information

For more information and updates, visit the CerTest website.

SABRE – Novel blade technologies greatly improve helicopter efficiency

Posted on by Bristol Composites Institute

We interviewed the lead investigator of the SABRE project, Dr. Benjamin Woods.

What is the SABRE project?

SABRE stands for ‘Shape Adaptive Blades for Rotorcraft Efficiency’. The four-year, €6 million, EU-funded project brings together a consortium of six research institutions from across Europe to develop ground-breaking new helicopter blade designs capable of changing shape in real-time to reduce noise, fuel burn and CO2 emissions.

Can you tell us what motivated this work?

In a word, sustainability. Reducing emissions from current flying technology is imperative if we want a credible chance to tackle climate change, hence developing new technologies that are more efficient and drastically reduce fuel burn is key to becoming more sustainable. 

How are you proposing to achieve better flying efficiency for helicopters?

yellow helicopter on the ground

Current designs for helicopter blades are rife with inefficiency.  The problem with helicopters is that blades will experience cyclic changes in airflow as they rotate. These differences in airflow velocity are detrimental to the performance of the rotor. This is a well-known issue and current rotor designs can change the overall pitch (orientation) of each blade as it spins around the helicopter to partially mitigate this issue. Unfortunately, the pitching solution is not ideal as it pitches the whole blade.  

Instead, we are proposing to develop different morphing concepts that will enable us to quickly and accurately control the shape of each blade and hence the airflow, during each rotation.  

What are these morphing concepts?

There are many key design parameters that should be considered when creating rotor blades. For example, you should ask ‘how much curvature is there in the aerofoil?’, ‘how does the length of the aerofoils vary over the blade?’, ‘how much twist is there in the blade?’. These are the types of features that engineers play with to optimise rotorcraft performance, with compromises being required due to the wide range of operating conditions. Those are the things that we would love to be able to change – but in real-time – to allow us to fully respond to the different operating conditions without the need to compromise. We are looking at exactly those factors. 

Six promising morphing blade concepts are being investigated. Two concepts can actively change the blade twist. Another two can actively change the aerofoil curvature (camber). One concept can increase the length of the aerofoil, and the last concept can alter the blade dynamic response.

Active camber, active chord, active tendons. active twist, and negative stiffness passive energy balancing.
Morphing concepts investigated by SABRE

What have you found out so far?

Using one concept at a time resulted in a fuel burn reduction of up to 5%, but when we looked at multiple concepts in different parts of each blade to attack different elements of physics, that’s when we saw significant reductions of up to 11%. There is certainly scope for further reductions, and with the right combination of technologies, fuel burn could be reduced by as much as 20%. 

What are your next steps?

It will be a while before this technology becomes mainstream. Development times of up to 30 years are “completely standard” for novel technologies in civil aerospace because the safety requirements are so rigorous. However, SABRE’s research could have applications elsewhere – more specifically, with renewable wind energy. This will likely be part of my next investigation.

Find out more

For more information, visit the SABRE Project website.