Next Generation Aerospace Composites using Carbon Nanotube based Fuzzy Fibre Technology Dr. Thomas Pozegic Prof. S. R. P. Silva Dr. I. Hamerton Mr. P. Ballocchi

Carbon Fibre Reinforced Plastics (CFRP) CFRP offers a 40% reduction in density over aluminium but the same strength as that of high-strength steels. My project was based on CFRP Revolutionised many industries including the the aerospace industry driven by the reductions in weight and retaining the strength of the outgoing metal. Has other improvements to.. High modulus (stiffness) High life expectancy under fatigue loading Improved dampening Reduced part count Smooth (aerodynamic) finish High thermal-dimensional stability

Carbon Fibre Reinforced Plastics High Strength High Modulus Low Density e.g Polyacrylonitrile Carbon Fibre Reinforced Plastics What is it? A composite where the fibres provide strength…. Distributes load Protection e.g. Epoxy Resin

Poor Electrical Conductivity Poor Thermal Conductivity With metallic mesh Static charge and lightning strikes Still rely on metallic sheets/mesh – heavy difficult to consolidate Lightning strike once every 3,000 flying hours Poor Thermal Conductivity Reducing fuel temperature and accumulating fuel vapour Anti/de-icing solutions However there are problem with composite materials… Emphasise the difficulty to consolidate the metallic mesh. For thermal conductivity just say that ‘the composites are not efficient at keeping the fuel cool and preventing vapour buildup and the anti/de-icing solutions aren’t as efficient for poor thermally conductive materials.

Carbon Nanotubes Carbon fibres (strength..) + Polymer matrix (protection, distributes loads..) Carbon Nanotubes AG Molekulare Genetik/TU Darmstadt Density: 1.4 g/cm3 (Al: 2.7 g/cm3) Stiffness: > 1 TPa (same as Diamond) Current carrying capacity: 109 A/cm2 (Cu: 106 A/cm2) Tensile strength: ~100 – 600 GPa (66% greater than carbon fibres) Thermal Conductivity: 6000 W/mK (Diamond: 3320 W/mK) Electrical Conductivity: Metallic Robert Johnson

CNTs Carbon Fibres However optimising the surface…. Describe images. Show sample

Thermal Analysis of Carbon Fibre Removal of the polymer sizing - (interfacial adhesion, infusion capability and handleability) However, as shown by the thermal gravimetric analysis – shows decomposition with temperature, there are two areas of degrdation At 350oC, the removal of the sizing and then the critical strength-loss temperature (complete decomposition of the carbon fibre) Highlight growth temperature. Critical strength-loss temperature

Fibre Analysis Single Fibre Tensile Test Tow Pull-Out Test Interfacial Shear Strength (MPa) Interfacial shear strength retained even after removal of the polymer sizing Toughening of interphase region Pull-out fracturing mechanism Only a 9.7% degradation Optical heating Water-cooled walls and substrate holder Thomas Pozegic et al. Carbon 2014 Thomas Pozegic et al. Comp. Part A. 2016

Composite Fabrication Composite Mechanical Test Resin Transfer Moulding Process Tensile Tests Tensile test is fibre dominated Tensile stress degradation carries through (-30%) Increase in Young’s modulus (+150%) Good wettability Thomas Pozegic et al. Sci Reports 2016 Thomas Pozegic et al. Comp. Part A. 2016

Composite Mechanical Tests Interlaminar Toughness In-Plane Shear Interlaminar Toughness Standard Fuzzy Fibre | Sample Fracture Toughness Standard 810 J/m2 Fuzzy Fibre 1480 J/m2 (+80%) Toughening of the matrix, interphase region (+20% in USS and +70% in SCM) Less dependence on fibre properties Strong interfacial shear strength correlated with enhanced IPS properties Pull-out toughening mechanism Crack propagation amongst strong nanostructures Thomas Pozegic et al. Comp. Part A. 2016

Electrical Conductivity Functionality Electrical Conductivity Thermal Conductivity 300 % 450 % 230 % Standard Fuzzy Fibre Thermal Conductivity (W/m.K) 100 % Standard Fuzzy Fibre Thomas Pozegic et al. Comp. Part A. 2016

Optimisation Significantly reduce the electron and phonon percolation threshold  increase the electrical and thermal conductivity Improve fracture toughness  propagating crack pathway around microstructures Increase shear properties Enhance Z-plane properties e- q Ideal situation

Future in Composite Design? Enhanced: Electrical conductivity (lightning strike protection without a mesh) Enhanced thermal conductivity (anti/de-icing, minimise fuel vapour formation) Increased interlaminar toughness and in-plane shear properties Effectively replaced the polymer sizing: Compatibility with polymer matrix (wet-out) Retain handleability and interfacial adhesion Multifunctional Energy storage Electrical conductive pathways Damage sensing Anti-icing & self-healing.. Interestingly observed a replacement for the polymer siszing Airbus

Thank you for your attention Special acknowledgement to Bombardier and EPSRC for funding this project Thank you for your attention Dr Thomas Pozegic E-mail: t.pozegic@bristol.ac.uk