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Hierarchical thermosetting composites

Project overview

In this project we seek to enhance the damage tolerance of traditional composite materials by introducing and optimizing carbon nanotube reinforcement. Although traditional carbon fibre/polymer composites exhibit outstanding in-plane properties due to the former bearing high stresses while the latter transfer them, they suffer from weak interlaminar fracture toughness, particularly under compressive and shear stresses. Carbon nanotubes are ideally suited for this application because of extraordinary stiffness and strength (Young’s modulus up to 1 TPa and tensile strength up to 30 GPa). When applied as additional reinforcement, the nanotubes should improve interfacial properties as a result of through-thickness reinforcement and increases in interfacial area. The final product will be a new generation of high strength and stiffness composite material. The first phase of this project will be to modify the epoxy matrix by introducing high weight fractions of nanotubes with good dispersion. These nanocomposites will be characterized for physical and mechanical properties to ascertain their suitability as a reinforced matrix in carbon fibre composites. Hierarchical composites (HCs) will be produced as tapes/prepregs from carbon fibre tows and the nanoreinforced matrix on a continuous processing line.

They will be characterized to determine nanotube dispersion, distribution and, if possible, orientation. Improvements in fracture toughness over conventional composites will be demonstrated under mode I, mode II and mixed-mode delamination. Ultimately, we will characterize key damage tolerance parameters, such as open hole compression (OHC) and compression after impact (CAI), locating HCs at critical ply interfaces. The project will culminate in demonstration of HC performance on a structural element, such as skin/stiffener pull-off test.

Researcher

Tomi Herceg
Postdoctoral Research Associate

Supervisors:
Prof. Alexander Bismarck
Prof. Milo Shaffer
Dr. Emile Greenhalgh 

Sponsor:
MAST

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