Category: Research

Research-based Automated Deposition: A new material characterisation and process development tool

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By Ege Arabul, Dr James Kratz & Dr Vincent K. Maes

Summary 

A new research tool has been developed and commissioned at the University of Bristol, see Figure 1, to investigate the Automated Fibre Placement (AFP) deposition process. The machine, named “Real-Time AFP”, allows for composite pre-preg tape to be delivered onto a surface in an AFP/ATL-representative manner, where the process parameters, such as compaction force, temperature, speed and tow tension, can be varied, and the material tack can be characterised. The device also monitors the deposited tape and captures data in real time, allowing for the detection of manufacturing defects and correlation to the process parameters. The device aims to accelerate research into a wide range of AFP related topics, including novel sensor development, real-time control algorithms, and dedicated material benchmarking standard for AFP processes. 

 

Figure 1– The newly commissioned Real-Time Automated Fibre Placement (RT-AFP) Machine in the Bristol Composites Lab (BCI). 

 

Introduction

Automated Fibre Placement is a technique to deliver semi-finished, composite pre-preg tape onto a surface where narrow pre-preg slices are collimated on the head and delivered together through the use of a gantry head, heater, and a compaction roller. This technique is particularly well suited for gently curved or larger structures where a robust and repeatable manufacturing technique is needed, such as in aerospace applications, and where variable stiffness composites are needed such as in hyperbolic blended wing bodies, c-spars, and engine fan blades, which can be achieved through tow steering.

While automation of composite manufacturing processes has been successfully industrialised, part inspection and re-work remains a manual process, which can take up to 42% of the total time per build (Rudberg, T, “A Process for Delivering Extreme AFP Head Reliability”, 2019). Furthermore, this inspection is usually conducted only visually, which is highly dependent on the skill of the technician. Supplemented by the increasing trends in Industry 4.0 and a global emphasis on sustainability aimed to reduce waste and increase efficiency in composite manufacturing, methods to detect and react to defects during manufacturing are of great industrial interest.

 

The Key Features and Capabilities of RT-AFP

The in-house “RT-AFP” rig was developed to address the gap between the AFP representative lab experiments and the full-scale AFP deposition using a commercial AFP machine, which has varying degrees of process complexity, as shown in Figure 2. A key consideration in developing this machine was to ensure it provided rich, in-process deposition data, which many commercial AFP solutions would not offer for research purposes.

The key features of this machine include;

  • Closed-loop control over AFP parameters, such as the layup temperature, compaction force, speed and tow tension.
  • A real-time data capture system, including laser scanner profilometry data, to monitor the deposition process.
  • Material tack characterisation capability via peel-tack-testing after deposition.
  • Implementation of novel sensors in a modular manner.
  • Ability to vary process parameters on the fly and implement different setpoint profiles.

 

Figure 2- Varying degrees of complexity in AFP research, with RT-AFP being in the middle.

 

Figure 3 illustrates the key components of the machine and its operating principles. The image on the left-hand side shows the loading of the composite pre-preg tape as it is being deposited. The pre-deposition and post-deposition laser scanners scan prior to and after the tape deposition, respectively, and can be used to subtract data from one another to identify the incoming tape and any misalignment or defects on the tape. After the deposition, the deposited tape can be peeled off by running the machine reverse.

Figure 3-The key components of the RT-AFP

 

Success Stories and Future Outlook

The “RT-AFP” has already been a critical resource for researchers investigating the AFP process. Some highlight studies include a comparison between the AFP and hot press processes for a layer-by-layer curing technology[1], a real-time defect detection system using laser scanners with convolutional neural networks to classify different types of deposition defects [2] and a real-time process control algorithm to mitigate influence of certain defects during deposition [3].

With strong ties to sensor development teams within the university, including non-destructive testing and evaluation, the “RT-AFP” is a growing tool to accelerate research. Along with these studies, the device is also being used to correlate the process parameters to the evolution of AFP manufacturing defects to better inform our understanding, and models of the AFP deposition process and to develop novel techniques to eliminate arising defects on the fly. The research team invites future collaborators investigating the AFP process, within and external to the university, to utilise the machine to accelerate their research capabilities.

 

Figure 4-Summary of key success stories using the RT-AFP

 

Linked Articles:

  1. Hartley, R., & Kratz, J. (2024). CFRP layer-by-layer curing using research-based automated deposition system. Manufacturing Letters, 40, 85–88. https://doi.org/10.1016/j.mfglet.2024.03.005
  2. https://composites.blogs.bristol.ac.uk/2023/11/30/real-time-quality-control-in-automated-fibre-placement-using-artificial-intelligence/
  3. Nguyen, D. H., Sun, X., Tretiak, I., Valverde, M. A., & Kratz, J. (2023). Automatic process control of an automated fibre placement machine. Composites Part A: Applied Science and Manufacturing, 168, 107465. https://doi.org/10.1016/J.COMPOSITESA.2023.107465

Bristol Composites Institute in Space

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By Prof. Ian Hamerton, Prof. Byung Chul Kim, & Dr Vincent K. Maes 

The high specific properties of composite materials have long made them of interest in space applications, where despite significant reductions over the years it still costs around $15 dollars per gramme of payload to get to Low Earth Orbit (LEO). However, significant challenges remain in terms of producing material systems capable of withstanding the harsh environments, manufacturing light weight components precisely, and developing innovative solutions to enabling future space missions. At the Bristol Composite Institute (BCI), several research activities are targeted at developments that will enable further utilisation of composites in space applications. These can broadly be grouped under three main challenges. 

Challenge 1: Getting to space. 

While the specific properties of composite materials are high, realising the true potential for lightweighting requires reliable defect free manufacturing as well as significant tailoring of the amount of material and orientation of fibres in different regions of the part. To this end, there have been two key developments at the BCI that promise to contribute to extreme light-weighting. WrapToR, or Wrapped Tow Reinforced, truss structured, led by Dr Ben Woods, combines the high specific properties of composites with the high geometrical efficiency of truss structures and the efficient and highly automatable wrapping process. 

 

A manufactured tow steered cylinderIn parallel, development of fibre steered composite structures, led by Prof. Byung Chul (Eric) Kim, has had several successful steps towards commercialization. Specifically, a recent academic – industrial collaborative effort, led by the European Space Agency (ESA), which designed and manufactured Rapid Two-Steered (RTS) cylindrical structure, see Figure 1, clearly shows its potential for launch vehicles, where the design focus is not on the strength but on the structural stability during launching. The produced structure was nominated for a JEC Composites Innovation award in 2022. This study, which is now being followed by an ESA-funded project to apply the same methods to a full scale space structure in collaboration with a prime space contractor, was led by Dr Rainer Groh in collaboration with a BCI spin-out company, iCOMAT, which is commercialising Continuous Tow Shearing (CTS) technology after the techniques was first developed within a BCI research project. iCOMAT are proactively engaging with the space industry having secured £4.8M from the UK Space Agency (UKSA) and very recently a further £22.5M Series A from venture capital, a rare feat for composite start-ups. 

Looking forward, next-generation automated composites manufacturing technologies are needed to enable highly efficient and complex composite structures that cannot be manufactured with current technologies. At BCI, 3D CTS technologies, see Figure 2, are under development which can manufacture complex space structures such as domes and nose cones without defects (see further reading for publication).  

Three people in a lab 

Figure 2 – The team at Bristol developing continuous tow stearing for 3D geometries (top) with examples of standard AFP quality (bottom left) vs CTS quality (bottom right). 

 

Challenge 2: Surviving space. 

Once gravity has been overcome, the materials that remain in space will be exposed to the extremely damaging effects of atomic oxygen, extreme temperatures and thermal cycling, galactic cosmic radiation, and other challenging environmental effects. To address these challenges Prof. Ian Hamerton has led and supervised several research activities around developing new composite materials. Current projects are funded by the UK Space Agency (UKSA) and the Defence and Security Accelerator (DASA) and include collaborations with the National Composites Centre (NCC) in two high profile ESA programmes. 

Initial developments began in 2017, when Oxford Space Systems funded a PhD studentship to study material survivability under space conditions. This work resulted in a family of polybenzoxazine (PBZ) nanocomposite resins, with enhanced resistance to degradation from the highly damaging effects of atomic oxygen, which has subsequently been studied in several research projects. 

These developments have led to the BCI contributing four composite samples to an experiment in the Euro Material Ageing Facility on the Bartolomeo module onboard the International Space Station (ISS). The samples were prepared with UKSA funding and are based on three PBZ resins and a novel cyanate ester resin, also designed in BCI. Transportation to the ISS on a SpaceX Dragon launch vehicle is planned for the autumn of 2024; where the samples will spend up to 18 months, orbiting the Earth, before being returned for further analysis. This is part of a £3.5M Euro Materials Ageing 1 campaign (funded jointly by ESA and CNES), designed to examine the effects of the LEO environment, see Figure 3, on 45 materials drawn from 15 international teams. 

 

A satellite in space

Figure 3 – In space materials are exposed to extreme temperatures and radiation, including charged particles which earth is shielded from by its magnetic field. [image credit: SSA, reproduced under ESA Standard Licence [non-commercial use]). 

In parallel, Prof. Hamerton’s team is also conducting projects to investigate chemically modified variants of the PBZ resins for their shielding characteristics towards galactic cosmic radiation, as well as the effects of LEO on the efficiency of thin (0.3 mm) deployable laminates. Another line of research is developing self-healing variants of PBZ polymer matrices, with the aim of improving the resilience of the composites against high velocity impacts from space debris – which is an important consideration for the final challenge. 

 

Challenge 3: Staying in space 

Once the payload is in space and resilient to the harsh environment, the goal now becomes to stay there and operate for as long as possible. With space agencies shifting their focus towards longer missions and even extraterrestrial habitats, cradle-to-cradle materials and processes that enable in-orbit and off-planet repair and manufacturing will become critical.  In this, both novel material and manufacturing developments within the BCI play a crucial role. 

Increased use of high performance thermoplastics as well as the potential to use reclaimed fibres using the patented HiPerDiF process, currently being commercialised as AFFTTM by another BCI spinout, Lineat Composites, combined with either fibre steering technologies or the WrapToR process, may enable low cost and scalable manufacturing. The specific coupling of HiPerDiF material and the WrapToR process is the current focus of a collaborative PhD project and related proposals to extend this work have recently submitted to the UKSA and ESA. Furthermore the WraptToR process has also been adapted into an extrusion like process, known as “TrussTrusion”, which could allow for compact payloads of raw materials which are then turned into the structural components once in space, or for re-production of recycled materials into new structural elements. 

Outlook 

While the challenges are great, the research already carried out and current developments are providing the building blocks and cornerstone technologies needed to enable the future of space exploration and travel. Providing both improved performance and sustainability, the research at the BCI is well placed to lead the way in the 21st century. 

Acknowledgements 

The challenges in developing new material systems and manufacturing process for space applications are profound, so it takes the efforts of many. Within the BCI contributions have been made by PhD researchers, past and present, post-doctoral researchers, academic staff, and our collaborators around the world including colleagues at the National Composites Centre. 

Further reading: 

Tailor-made composites for tougher space structures, [web], 08/06/2022, https://www.esa.int/Enabling_Support/Space_Engineering_Technology/Tailor-made_composites_for_tougher_space_structures 

 

Lincoln, R., Weaver, R., Pirrera A., and Groh, R., Manufacture and buckling test of a variable-stiffness, variable-thickness composite cylinder under axial compression. AIAA SCITECH 2022 Forum, San Diego, CA, January 3-7, 2022. https://doi.org/10.2514/6.2022-0664 

 

Press release: £47 million investment to supercharge space infrastructure across the UK. UK Space Agency, [web], 22/11/2023, https://www.gov.uk/government/news/47-million-investment-to-supercharge-space-infrastructure-across-the-uk 

 

Rosario Grabriel, E., Rautmann, M, and Kim, B.C. Continuous tow shearing for the automated manufacture of defect-free complex 3D geometry composite parts. Composites Part A, 183, 2024. https://doi.org/10.1016/j.compositesa.2024.108212 

 

Why Space? The Opportunity for Materials Science and Innovation, version 1.2.1, M. Lappa, I. Hamerton, P.C.E. Roberts, A. Kao, M. Domingos, H. Soorghali, P. Carvil (Eds.), STFC and UK Sat Apps, February 2024. (including Considerations for Material Development and Manufacturing in Space, Hamerton, I., Roberts, P. & Carvil, P. pp. 35-40). 

 

Effect of atomic oxygen exposure on polybenzoxazine/POSS nanocomposites for space applications, He, Y., Suliga, A., Brinkmeyer, AW., Schenk, M. & Hamerton, I., 2024, In: Composites Part A: Applied Science and Manufacturing. 177, 107898. https://doi.org/10.1016/j.compositesa.2023.107898 

 

Physical and mechanical properties of nano-modified polybenzoxazine nanocomposite laminates: Pre-flight tests before exposure to low Earth orbit, Kong, K., Gargiuli, J. F., Kanari, K., Rivera Lopez, M. Y., Thomas, J., Worden, G., Lu, L., Cooper, S., Donovan-Holmes, S., Mathers, A., Hewlings, N., Suliga, A., Wessing, J., Vincent-Bonnieu, S., Robson Brown, K. & Hamerton, I., 20 Feb 2024, (E-pub ahead of print) In: Composites Part B: Engineering. 111311. https://doi.org/10.1016/j.compositesb.2024.111311 

 

Development of cyanate ester-oligosiloxane copolymers for deployable satellite applications, Rivera Lopez, M. Y., Suliga, A., Scarpa, F. & Hamerton, I., 11 Dec 2023, (E-pub ahead of print) In: Polymer. https://doi.org/10.1016/j.polymer.2023.126573 

 

Development of Cycloaliphatic Epoxy-POSS Nanocomposite Matrices with Enhanced Resistance to Atomic Oxygen, Rivera Lopez, M. Y., Lambas, J., Stacey, J. P., Gamage, S., Suliga, A., Viquerat, A., Scarpa, F. & Hamerton, I., 25 Mar 2020, In: Molecules. 25, 7. https://doi.org/10.3390/molecules25071483 

 

Morabito, F., Macquart, T., Schenk, M., and Woods, B.K.S. Continuously extruded wrapped tow reinforced truss beams. Journal of Reinforced Plastics and Composites, 2024. https://doi.org/10.1177/07316844241242884 

CoSEM CDT STEM Outreach Day

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On the 20th May, our CoSEM CDT hosted a STEM Outreach Day for a group of 40 Sixth-Form pupils from Katharine Lady Berkeley’s School in Gloucestershire. Led by the current CDT and PhD students, there were four activities that ran throughout the day, highlighting the exciting opportunities in Composites Engineering.

The EPSRC Centre for Doctoral Training in Composites Science, Engineering and Manufacturing (CoSEM CDT) welcomed Sixth Form pupils from Katharine Lady Berkeley’s (KLB) School in Gloucestershire. The CoSEM CDT students and Aerospace PhD students led activities that showcased the work they are engaged in and gave a taster of the type of exciting research being done in the programme.

After a Welcome from Dr Jemma Rowlandson and mini-lecture on Aeronautics from CoSEM Student Matthew Lillywhite, the pupils spent the day in General Engineering laboratory for a variety of hands-on activities. One activity, created by Dr. Ben Woods, was the creation of an aeroplane wing which required pupils in small groups to make decisions to craft a wing that took into consideration aerodynamics and the lift/drag ratio.

The KLB pupils also utilised a crushing apparatus devised by the University’s NextCOMP research team. Using jelly and dried pasta, the pupils were tasked with creating a sample that could withstand the most weight. In an additional NextCOMP activity, the pupils experimented with reinforcing chocolate bars and seeing how they performed under a pendulum test.

The final activity was to create a marble run, and under guidance from Dr Jemma Rowlandson the groups competed to build and test marble runs that met certain parameters.

Jurg Laderach, Maths teacher from KLB school said: “I was so impressed by the interactions between your department and our students. This is exactly how outreach should be done! I overheard many good conversations about career options and your students were brilliant at encouraging our students to choose the path that is right for them and go with what they enjoy. Your students talked with infectious passion about what they do.”

Additional support to run the day was given by: Jo Gildersleve (NextCOMP), Dr Jemma Rowlandson, Dr Ben Woods and Matthew Lillywhite, UoB Active Outreach team, and the CDT Directors and Staff.

 

A group of Sixth Form students are being taking part in the NextCOMP Crusher activity, guided by a current CDT student.A group of Sixth Form students are being taking part in the NextCOMP Crusher activity,    guided by a current CDT student. Photo credit: James Griffith

 

 

A group of Sixth Form students engaged in the activity of creating an aeroplane wing. A group of Sixth Form students engaged in the activity of creating an aeroplane wing. Photo credit: James Griffith

 

A group of Sixth Form students testing their Marble Run.  A group of Sixth Form students testing their Marble Run. Photo credit: James Griffith

BCI PhD Student Wins SAMPE UK Competition

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We are proud to announce that PhD student Nicolas DARRAS has won the 2024 SAMPE UK & Ireland Student Seminar Competition, alongside Badr Moutik from University of Plymouth.

Nic’s presentation titled “Investigation on the manufacture of hierarchical composites and their mechanical compressive performances” impressed the judges and a result he will be representing SAMPE UK at the SAMPE Europe competition (part of the SAMPE Europe conference taking place in Belfast in September).

Nic said “Participating in the SAMPE Student Seminar competition was a tremendous experience, allowing me to enhance my presentation skills and shine a light on the novel research within the NextCOMP programme. As one of the UK representatives, I eagerly anticipate the SAMPE Europe conference in September, where I’m excited to showcase our innovative projects on an international stage.”

Tim Wybrow, SAMPE UKIC Chairman, said, “I am really impressed with all the student researchers this year. We have decided as a committee that as a congratulations and thank you for their efforts, each participant will be offered a complimentary one-year membership to the organisation.”

CIMComp Hub Storytelling Workshop Review

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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

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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

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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 listen to the 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 

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

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

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

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

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

1. Live data collection and pre-processing;

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

3. Defect detection/classification using the CNN.

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

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

 

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

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/.