Science led vs design led teaching approaches in materials science and engineering for aeronautical engineering students

A comparison on teaching styles has been conducted by analysing behavioural, cognitive, developmental, social cognitive and constructivist perspectives of 26 students (higher engineering apprentices). All of those students are in their full-time employment at Broughton factory (Airbus UK) and were comprehensively surveyed at the end of module (ENGF405: Composites and Aeronautical Materials) to quantify their learning experiences. It is generally assumed that design led, in comparison to science led, approach is the most appropriate method for these hands-on engineering professionals. However, presented results are quite interesting because majority of the high achievers have opted for science led approach for their improved learning experiences during the module

Epoxy – the hub for the most versatile polymer with exceptional combination of superlative features

Epoxy resins and epoxy based materials have experienced significant advancement since their beginning in 1936, when Dr. Castan of Switzerland and Dr. Greenlee of USA succeeded in synthesizing the very first bisphenol-A-based epoxy resins. Whether it is the new carbon fiber composite of Boeing’s Dreamliner or the thin set terrazzo flooring, epoxy has always been the ideal choice because of its superlative properties and unique chemical composition. Belonging to thermoset family, it is certainly one of the most versatile polymers we see around in composites, aerospace, automotive, marine, sports materials, construction, structures, electrical and electronic systems, biomedical devices, thermal management systems, adhesives, paints and coatings, industrial tooling and other general consumer products. Because of its versatile nature, epoxy is replacing many conventional materials, e.g. epoxy based materials have already replaced wood in majority of the boats and various sports goods. Epoxy is an open-access journal and offers a fast and comprehensive peer-review. To ensure that the journal has the largest possible impact in this early phase, no publication fees will apply until the end of 2015

Carbon nanotubes for epoxy Nanocomposites: a review on recent developments

Carbon nanotubes (CNTs) are one of the strongest and stiffest engineering fibres. Due to their unique combination of chemical and physical properties at an incredibly small size, they possess great potential to be used as nanofillers for many structural and functional materials, particularly in aerospace sector. Depending on the type, geometrical parameters, concentration, dispersion and many other factors, CNTs can significantly modify the mechanical, electrical and thermal properties of epoxy based materials. This review paper, covering methods of synthesis, composite processing techniques and properties, presents an overview of develop-ments in the field of CNT/ epoxy nanocomposites in recent years

Re-agglomeration of carbon nanotubes in two-part epoxy system; influence of the concentration

Carbon nanotubes, because of their exceptional mechanical properties, are one of the potential reinforcements for polymers in near future. Before substituting these nanocomposites in commercial applications, there are many problems, like dispersion, agglomeration, cost effectiveness etc., which need to be sorted. Processing such nanocomposites for longer durations is quite frequently observed these days. Apart from the other major obstacles, re-agglomeration, because of strong van der walls forces between carbon nanotubes, is one of the latest problems that has been always underestimated and ignored. In this study, different carbon nanotubes (Single-wall nanotubes (SWNT), Double wall nanotubes (DWNT), Amino-modified double wall nanotubes (DWNT-NH2), Thin Multi wall nanotubes (MWNT) and COOH-modified thin multi wall nanotubes (MWNT-COOH)) at different concentrations (0.025, 0.05 and 0.1 %wt) in two-part epoxy system (Liquid Epoxy, Liquid hardener and Liquid epoxy-hardener mixture) were studied involving nano-particle size analyzer. After a study of 3 hours, it was observed that there is a strong dependence of re-aggregation profile on the employed homogenizing technique, i.e. high-power bath ultrasonication in this study. Apart from nanotubes/epoxy mixture, higher concentrations yielded higher aggregates profile and vice versa. Re-agglomeration, with the passage of time, in liquid epoxy was found to be least as compared to liquid hardener and liquid epoxy-hardener mixture. Hardener in liquid-epoxy mixture was the main culprit responsible for re-aggregation. Results were further verified by scanning electron microscopy, which revealed significant differences in the microstructures of the cured and fractured samples. Suggestions for altering processing parameters in order to avoid this major obstacle are discussed

Vibration and buckling of cross-ply composite beams using refined shear deformation theory

Vibration and buckling analysis of cross-ply composite beams using refined shear deformation theory is presented. The theory accounts for the parabolical variation of shear strains through the depth of beam. Three governing equations of motion are derived from the Hamilton’s principle. The resulting coupling is referred to as triply coupled vibration and buckling. A two-noded C1 beam element with five degree-of-freedom per node is developed to solve the problem. Numerical results are obtained for composite beams to investigate modulus ratio on the natural frequencies, critical buckling loads and load-frequency interaction curves

Rapid microwave processing of epoxy nanocomposites using carbon nanotubes

Microwave processing is one of the rapid processing techniques for manufacturing nanocomposites. There is very little work focussing on the addition of CNTs for shortening the curing time of epoxy nanocomposites. Using microwave energy, the effect of CNT addition on the curing of epoxy nanocomposites was researched in this work. Differential scanning calorimetry (DSC) was used to determine the degree of cure for epoxy and nanocomposite samples. CNT addition significantly reduced the duration for complete curing of epoxy nanocomposites. As compared to monolithic cured epoxy, 20.5% of decrease in time and 12.5% decrease in spent consumed energy were observed for 0.2 wt.% CNT filled epoxy nanocomposite

Improving oxidation resistance of carbon nanotube nanocomposites for aerospace applications

Carbon nanotubes (CNTs) based materials possess strong potential to substitute various functional materials developed exclusively for aerospace applications. However, because of the low oxidation temperature of CNTs (400-500 oC), using CNT based ceramic nanocomposites in high temperature applications can be problematic. Making ceramic-CNT nanocomposites by atomic layer deposition (ALD) method and field assisted sintering technology (FAST) is a good route to improve oxidative stability of CNTs. In this study, thermo-gravimetric analysis (TGA) of alumina coated CNTs (prepared by ALD) and alumina-CNT nanocomposites (prepared by FAST) were carried out. 16% improvements were observed in the oxidation resistance for alumina-CNT nanocompo-sites prepared by ALD and SPS techniques. Different strategies to improve oxidation resistance are discussed

Advanced nanocomposite materials for subsea oil & gas production

The search for novel materials has continued to dominate industries like automotive, power, aerospace and energy where maintaining a competitive edge is necessary for increasing industry market share. For subsea applications, where high pressures and temperatures are the norm, using reinforced composites have potential as the next generation solution. This presentation investigates the influence of micro/nano fillers on mechanical properties of lightweight polymeric materials employed in thermoplastic risers and hoses for subsea applications and the challenge of incorporating such novel materials for potential up-scaling. To obtain commercially viable microstructures, a two-step processing routes was selected and its influence on final polymer nanocomposite morphology has been studied

Fullerenes for enhanced performance of novel nano-exploited aircraft materials

Fullerene is an allotropic form of carbon having a large spheroidal molecule consisting of a hollow case of sixty or more carbon atoms. In the past decade, this family of super carbonaceous materials is subject of significant research interest for their utilization in an increasing number of applications including energy, transportation, defense, automotive, aerospace, sporting goods, and infrastructure sectors. Carbon nanotubes and graphene are some of the common types of fullerenes. This presentation will look into how a simple chemical manipulation at nano-scale of a superlative chicken wire structure of graphene can be exploited to address major engineering challenges we are now encountering in the development of non-metallic reinforced plastic aircrafts like Airbus A350 and Boeing Dreamliner 787. Substituting metallic accessories, like Expanded Copper Foil (ECF) used for lighting strike protection, with graphene in the wings of carbon fiber reinforced polymer composites aircrafts is currently being extensively researched at industrial scale. This substitution offers good chemical compatibility with the base matrix material (epoxy) and can solve various existing issues. It would also offer other benefits, like in-situ structural health monitoring of aircraft components and improved mechanical properties and structural integrity as well. However, there are several challenges prior to this forthcoming substitution, as being dealt by leading aircraft manufacturers of Europe and USA, which will be discussed in detail

Fractography analysis of 1.0 wt% nanoclay/multi-layer graphene reinforced epoxy nanocomposites

The topographical features of fractured tensile, flexural, K1C, and impact specimens of 1.0 wt% multi-layered graphene/nanoclay-epoxy nanocomposites have been investigated. The topographical features studied include maximum roughness height (Rmax or Rz), root mean square value (Rq), roughness average (Ra), and waviness (Wa). Due to deflection and bifurcation of the cracks by nanofillers, specific fracture patterns are observed. Although these fracture patterns seem aesthetically appealing, however, if delved deeper, they can further be used to estimate the influence of nanofiller on the mechanical properties. By a meticulous examination of topographical features of fractured patterns, various important aspects related to fillers can be approximated such as dispersion state, interfacial interactions, presence of agglomerates, and overall influence of the incorporation of filler on the mechanical properties of nanocomposites. In addition, treating the nanocomposites with surfaces of specific topography can help improve the mechanical properties of nanocomposites