Extended projects 2020 cohort
- Sustainable green concrete with recycled plastics, fibres, and bacteria
- Intelligent composites forming - simulations for faster, higher quality manufacture
- Exploration of design space for a compliant fairing of a folding wingtip
- Nanocomposites excitonic superconductors
- Investigation into the effect of material parameters on electromagnetic induction heating of carbon composites using numerical modelling
- Digital engineering of composite materials for space applications
- The development of functional conjugated microporous polymers for hydrogen storage
- Influence of automated fibre placement processing parameters on the consolidation of out-of-autoclave prepreg
- Forming of thermoplastic prepreg with aligned High-Performance Discontinuous Fibre (HiPerDiF) for sustainable composite manufacturing
Sustainable green concrete with recycled plastics, fibres, and bacteria
Student: Meiran Abdo
Supervisors: Valeska Ting, Andrea Diambra (CIV), Fabrizio Scarpa, Adam Perriman (SMM), Gianni Comandini
Reinforced concrete is responsible for around 7% of carbon dioxide emission every year, but it is also a critical material in Civil Engineering. Reinforced concrete is a composite with a matrix composed of water, cement, and aggregates. The matrix exhibits good behaviour for compression, while for tensile loads its resistance is just 1/10th of the compressive load. Steel bars are inserted in the concrete to achieve better tensile stiffness and strength mass, however, to preserve the durability of the structural element, the pH of concrete must remain around 13. In an alkaline environment rebar is therefore protected from oxidation. Unfortunately, cracks may occur which cause steel reinforcements to oxidize.
There are three main consequences of this phenomenon. First, a loss of resistance of the structural element is present due to the reduction of the reactive area of the rebar caused by the oxidization of the steel section. Secondly, an increment of the permeability of the structural member is also present. Lastly, the increasing volume of the steel section due to rust will lead to an expulsion of the remaining concrete layer around the steel section. Solving the crack problem in concrete is essential for the durability of structures, and to guarantee better safety conditions for infrastructure.
This investigation aims use fibres from composite and other types of waste to understand the best way to produce fibres from recycled composite and waste materials and to assess both the short-term and long-term mechanical performance for concrete mixed with carbon fibre. Experimental work conducted to study the effect of reinforcement in the concrete, as well as prepare specimens and test them after artificial cracking.
Intelligent composites forming - simulations for faster, higher quality manufacture
Student: Siyuan Chen
Supervisors: Jonathan Belnoue, Stephen Hallett, Adam Thompson, Tim Dodwell (University of Exeter)
In this work, a way to the destination of reducing defect level in dry textile forming process was explored. The effect of using springs to assist the forming process was explored by FE simulation approach, supported by a shell-membrane hybrid forming process FE model. A batch of 90 simulations were conducted, of which the results indicate the sensitivity of forming quality to the controllable variables. Two samples from the 90 got lower sum of squared-distance (positive to the defect level) than the baseline model, indicating a possibility to reduce defect level through this road, especially considering the volume of samples is difficult to have a full coverage of the parameter space of 9 input variables.
In the next step, more simulations will be conducted based on the analysis of current data. A machine learning based surrogate model will be established to provide rapid regression and prediction of the forming quality, which is fed with FE simulation results to train and validate. In a long run, this would allow the construction of a fully autonomous forming rig with embedded sensors and active controls where the manufacturing conditions are adapted on the fly and defect formation mitigated based on rich live experimental data feeding into real-time simulation and optimization of the process.
Exploration of design space for a compliant fairing of a folding wingtip
Student: Nuhaadh Mahid
Supervisors: Ben Woods, Mark Schenk, Brano Titurus, Tom Wilson (Airbus)
The Semi-Aeroelastic Hinge concept introduces a folding wing tip device for gust load alleviation. One of the major challenges in the physical realization of the concept in civil aircraft is the requirement for a compliant fairing to cover the discontinuity in the skin surface created by the hinge. The fairing is aimed at providing a smooth, compliant surface to improve the aerodynamic performance while keeping the folding stiffness of the wingtip to a minimum. This project identifies different architectures for folding devices and compliant skin surfaces. It also includes a numerical study on the effects of geometric and elastic parameters of the folding device on the folding stiffness and the smoothness of the surface. This research indicated that high out-of-plane stiffness and pre-tension on the skin are desirable to maintain a smoother surface. It was shown that a longer fairing along the span with a minimal elastic modulus of the skin in the direction across the hinge is desirable to attain a lower folding stiffness.
Nanocomposite excitonic superconductors
Student: Rikesh Patel
Supervisors: Simon Hall, Chris Bell, Steve Eichhorn
Around 60 % of all electrical energy generated worldwide is lost to resistive heating of transmission wires, leading to more fossil fuels being needed to make up the shortfall, and hindering the use of green alternatives. With the ability to transmit electricity with zero electrical resistance, superconducting wires would resolve the problem of resistive losses in the grid. However, this is not yet realised since current superconductive technologies require cryogenic cooling to function. It, therefore, remains a holy grail of the technology to realise superconductivity at ambient temperatures and pressures. This project aims to realise such a material by making a nanocomposite between transition metal dichalcogenides (oxygen group element) and carbon.
In this project, first nanoparticles of WSe2 and TiSe2 will be made and characterised by a suit of characterisation methods including, Ultraviolet and Visible Light Spectroscopy and Transmission Electron Microscopy (TEM). These nanoparticles will then be composited with carbon. Initially, functionalised (with metallophilic functional groups on the surface) carbon fibres will be used with the goal of ‘sticking’ the particles to individual carbon fibres. These will then be tested for superconductivity using a Superconductive Quantum Interference Device (SQUID), the gold standard for these tests.
The outcome of this project has the potential to revolutionise not only how electricity is transmitted but also how it is generated.
Investigation into the effect of material parameters on electromagnetic induction heating of carbon composites using numerical modelling
Student: James Uzzell
Supervisors: Dmitry Ivanov, Laura Pickard, Ian Hamerton, Ivana Partridge
Induction heating is a fast and energy efficient method of volumetrically heating carbon fibre composites which has large potential within different applications, such as rapid curing and repair. This study investigates how the heat sink and heat supply effects produced during induction heating of carbon fibre reinforced polymers, CFRP, are affected by the addition of metallic braids tufted through thickness. The research was conducted using finite element models to compute the electromagnetic and thermal distributions during heating using a simplified coil geometry. A parametric study varying the electrical and thermal conductivity of the braids was conducted to evaluate their impact on the heat sink. The study found that the addition of copper braids of conductivity used in the baseline tufted model increased the maximum temperature achieved during heating from 92 degrees to 155 degrees, based on a 6 Amp power supply at 300kHz. However, further increasing the thermal conductivity of the braids decreased the maximum temperature produced in the laminate. This shows that the heat sink was dominant under these conditions and thermal conductivity is the key mechanism in impacting the heat sink effects produced.
Digital engineering of composite materials for space applications
Student: George Worden
Supervisors: Kate Robson-Brown, Ian Hamerton, Ian Bond
This project is made up of preliminary work carried out to inform creation of a digital twin model of composite materials as they are used in space. This digital twin will simulate the effect of the low earth orbit (LEO) environment on polymer matrix composites, focussing on the effect of atomic oxygen. Atomic oxygen forms in the upper atmosphere and causes a significant amount of erosion to the exposed areas of spacecraft in LEO. At this stage, surface condition, thermal and chemical data regarding a number of samples has been collected using optical microscopy, DSC, and FTIR has been carried out. Further methods that will be used to expand this dataset are also outlined in this report, including mechanical testing and 3D CT scanning of the samples. The ultimate goal of this project is for the digital twin to accurately simulate LEO performance of composite materials. Once this has been achieved the model will be used to help develop a new generation of composite materials that can be optimised for use in space and ideally add new smart functionality such as a self-healing system.
The development of functional conjugated microporous polymers for hydrogen storage
Student: John Worth
Supervisors: Charl Faul, Valeska Ting
The depletion of traditional fossil fuels on such a comprehensive scale has led to calamitous global climate change and severe environmental concerns. Hydrogen is a promising candidate to replace existing finite petroleum-based energy sources because of its remarkable gravimetric energy density, clean combustion and abundance. However, the storing of hydrogen presents significant challenges because of its low volumetric density at ambient temperatures. Currently, the industry standard for storage is to highly compress hydrogen at ambient temperatures. This strategy suffers from eventual compression losses and demands lightweight, mechanically high performing and costly containment structures.
Adsorption of hydrogen in porous materials is a promising alternative to compression. Physical storage in conjugated microporous polymers is of particular interest due to their porous characteristics and metal-free, environmentally friendly chemical composition. Inspired by promising carbon dioxide uptake capabilities, nitrogen-containing conjugated microporous polymers with high specific surface areas have been synthesised via Buchwald—Hartwig amination reactions and their ability to adsorb hydrogen under specific conditions studied. Attempts to optimise these materials by the tuning of surface area, pore size distribution, pore volume and therefore the ultimate material functionality were also performed to demonstrate the material’s potential contribution towards carbon neutrality/net-zero.
Influence of automated fibre placement processing parameters on the consolidation of out-of-autoclave prepreg
Student: Axel Wowogno
Supervisors: James Kratz, Iryna Tretiak, Stephen Hallett
Composite materials are widely used in the aerospace industry due to high performance needs. However, autoclave curing, one of the most commonly used manufacturing processes, represents a bottleneck in the production workflow despite its effectiveness for part consolidation.
Making use of the Automated Fibre Placement (AFP) process, an online consolidation approach has been developed for component creation. In order to fully comprehend the impact of the process parameters, it is essential to first assess the consolidation behaviour of the selected material. By monitoring the evolution of the thickness and the in-plane compaction area of cruciform samples (initially 2mm thick and 30x30mm2 wide), this study investigates the consolidation behaviour of an out-of-autoclave curable carbon fibre reinforced epoxy prepreg system. Two experimental programs were used to examine the material’s behaviour by varying process parameters, such as pressure magnitude (from 0.05 MPa to 0.25 MPa), pressure application time (from 1s to 20 min) and temperature (from 30°C to 210°C). Upon evaluation of the samples’ thinning, widening and post-compaction defects (void sizes and distribution), optimal process parameters that would allow the production of enhanced quality parts that do not require autoclave processing, are identified.
This work represents one of the firsts steps towards the understanding of the influence of process conditions on the material behaviour and final part quality and towards the development of a novel out-of-autoclave manufacturing process.
Forming of thermoplastic prepreg with aligned High-Performance Discontinuous Fibre (HiPerDiF) for sustainable composite manufacturing
Student: Burak Ogun Yavuz
Supervisors: Jonathan Belnoue, Marco Longana, Ian Hamerton & Stephen Hallett
Although composite materials can play a role part in the decarbonisation of transport, through structure lightweighting, they are inherently challenging in terms of sustainability. This is because the high-performance composites used in the aerospace and automotive sector are often made of carbon fibres and thermosets resins that are difficult to recycle.
The HiPerDiF (High-Performance Discontinuous Fibre) method, invented at the University of Bristol, offers a way to remanufacture composites from reclaimed fibres. The method allows the production of composites comprising high-volume fractions of highly aligned discontinuous fibres, with high processability and performance. Still, greater sustainability credentials can be gained by using thermoplastic matrices which have a greater potential for recycling.
This study aims to develop a forming simulation tool for the manufacturing of thermoplastic HiPerDiF tapes, which are composed of 3mm long carbon fibres and PLA matrix. The tool is expected to be validated by forming experiments. This can help in the development of a robust manufacturing process for the highly formable HiPerDiF thermoplastic matrix tapes.