Tahreem Naveed

Project description

While conventional fibre reinforced polymer composites are widely used in automotive industry because of their light weight, high strength and stiffness, they lack the ability to absorb energy prior to failure. Hence, leading to catastrophic failure of structures without any prior warning. This prohibits the use of conventional CFRP composites in critical structural applications which may be subjected to earthquake, collision or blast. Hence, researchers are now working to improve the energy absorption ability of CFRP composites without compromising their strength and stiffness.

Hybrid fibre composites were developed by combining the low elongation and high elongation fibres in a polymer matrix. The research carried out on hybrid fibre composites showed that this combination enhances the structural performance as well as the energy absorption ability of fibre composites

The aim of my project is to integrate the hybrid composites in the industrialised composite automotive process chain. This aim will be achieved in three main steps. The first step will require to understand and predict the link between material, microstructure and mechanical properties of hybrid composites. In the second step a design process will be established to reduce cost and increase weight savings using hybrid composites. Finally, the last step will involve a demonstration that these hybrid composites can be used in the existing process chain (including paint shop).

Education

PhD researcher at BMW Germany (2019 – Present)

MSc in Advanced Mechanical Engineering from Imperial College London (2017 – 2018)

Research interests

Experimental testing of composites, numerical simulation of damage and failure in composites and recycling of composites.

Personal note

Outside of work and studies I like exploring new places and meeting with people belonging to different cultures. Going on road trips with my friends and family help me to disconnect for sometime from work related stress and gives me an opportunity to relax my mind and body.

I feel strongly about the in-availability of good education to women in rural areas of under-developed countries. Hence, it is one of my future goals and dream to build an educational institute in the rural areas of Pakistan where women can get basic education and can become aware of their rights.

Latest publications by this author

Improving the performance of pseudo-ductile hybrid composites by film-interleaving [OPEN ACCESS]

Salvatore GiacomoMarino, GergelyCzél

Improvement of the interfacial fracture toughness of the layer interfaces is one way to increase the performance of interlayer hybrid laminates containing standard thickness carbon/epoxy plies and make them fail in a stable, progressive way. The layer interfaces were interleaved with thermoset 913 type epoxy or thermoplastic acrylonitrile–butadienestyrene (ABS) films to introduce beneficial energy absorption mechanisms and promote the fragmentation of the relatively thick carbon layer under tensile loads. Carbon layer fragmentation and dispersed delamination around the carbon layer fractures characterised the damage modes of the epoxy film interleaved hybrid laminates, which showed pseudo-ductility in some cases. In the ABS film interleaved laminates, a unique phase-separated ABS/epoxy inter-locking structure was discovered at the boundary of the two resin systems, which resulted in a strong adhesion between the fibre-reinforced and the thermoplastic layers. As a result, the delamination cracks were contained within the ABS interleaf films.

Effect of Plasma-Treatment of Interleaved Thermoplastic Films on Delamination in Interlayer Fibre Hybrid Composite Laminates [OPEN ACCESS]

Salvatore Giacomo Marino, Florian Mayer, Alexander Bismarck and Gergely Czél

Safe, light, and high-performance engineering structures may be generated by adopting composite materials with stable damage process (i.e., without catastrophic delamination). Interlayer hybrid composites may fail stably by suppressing catastrophic interlayer delamination. This paper provides a detailed analysis of delamination occurring in poly(acrylonitrile-butadiene-styrene) (ABS) or polystyrene (PS) film interleaved carbon-glass/epoxy hybrid composites. The ABS films toughened the interfaces of the hybrid laminates, generating materials with higher mode II interlaminar fracture toughness (GIIC), delamination stress (σdel), and eliminating the stress drops observed in the reference baseline material, i.e., without interleaf films, during tensile tests. Furthermore, stable behaviour was achieved by treating the ABS films in oxygen plasma. The mechanical performance (GIIC and σdel) of hybrid composites containing PS films, were initially reduced but increased after oxygen plasma treatment. The plasma treatment introduced O-C=O and O-C-O-O functional groups on the PS surfaces, enabling better epoxy/PS interactions. Microscopy analysis provided evidence of the toughening mechanisms, i.e., crack deflection, leading plasma-treated PS to stabilise delamination.

Understanding the mechanical response of glass and carbon fibres: stress-strain analysis and modulus determination

Rajnish Kumar, Lars P Mikkelsen, Hans Lilholt and Bo Madsen

Accurate characterization of fibres is crucial for the understanding the properties and behaviour of fibre-reinforced composite materials. Fibre properties are key parameters for composite design, modelling and analysis. In this study, characterization of mechanical properties of glass and carbon fibres has been performed using a semi-automated single-fibre testing machine. Based on a sample set of 150 glass and carbon fibers fibres, engineering and true stress-strain curves are analyzed. Different modulus determination methods are discussed based on true stress-strain and tangent modulus-strain relationships. For glass fibres, the true stress-strain based tangent modulus is found to be independent of applied strain, whereas for carbon fibres, a tendency of tangent modulus to increase with applied strain is observed. The modulus of glass fibres is found to be independent of fibre diameter, whereas carbon fibres with smaller diameter show higher modulus compared with carbon fibres with larger diameters.