Search results for "Advanced composite materials"
showing 8 items of 8 documents
Mechanical Properties of CNT/Polymer
2018
Abstract The high mechanical properties, the stiffness-to-weight and strength-to-weight make the carbon nanotubes a perfect reinforcing agents in advanced composites. This interesting potential has attracted the attention of both industry and academia that have committed to this research field an impressive amount of work. Several applications of carbon nanotubes enriched polymer composites have already been seen: aerospace structures, sporting goods, automotive components, medical devices, optical barriers, photovoltaic devices, conducting plastics, electromagnetic interference shielding, efficient electrostatic painting of plastics, composite mirrors, plastics with high thermal dissipatio…
Visual indicator for the detection of end-of-life criterion for composite high pressure vessels for hydrogen storage
2012
International audience; A model to predict the accumulation of fibre breaks in advanced composites, that takes into account all physical phenomena implicated in fibre failure (i.e. the random nature, stress transfer due to breaks, fibre debonding and viscosity of the matrix) shows clearly that the failure of a unidirectional composite structure results in the formation of random fibre breaks which at higher loads coalesce into clusters of broken fibres. This stage of development is followed almost immediately by failure. This has direct application to filament wound pressure vessels of the type used to store hydrogen under high pressure. A novel, cost effective, method of revealing developi…
Longitudinal Flexure as a Method for Determining the Flexural Strength of Composite Materials
2004
A method is presented for determining the flexural strength of composites from tests on pinned specimens in axial compression. This scheme is close to the so-called Euler buckling model, but the load is applied eccentrically, and the bar is bent practically from the beginning of loading. An analytical model is proposed for calculating the flexural stress in longitudinal flexure of a thin bar in the case of large displacements. The problem is solved in elliptic integrals of the first and second kinds. The analytical model shows an excellent agreement with experiments. The results obtained are compared with experimental tension data. A device is also designed for testing composite bars in lon…
Quantifiable analysis of the failure of advanced carbon fibre composite structures leading to improved safety factors
2022
Abstract The increasing use of advanced composite materials means that they must now be considered as major materials for a wide variety of structures some of which will be in service for decades. There is therefore an important need to be able to quantify damage accumulation leading to failure in these materials particularly as they are often used in extreme situations for which failure must be avoided. This review shows how damage accumulation in many major composite structures is dominated by fibre failure but that the viscoelastic nature of the matrix induces time effects including delayed failure. It is shown that damage accumulation can be quantitatively modelled using a multi-scale a…
Ionizing radiation induced curing of epoxy resin for advanced composites matrices
2005
Abstract The radiation curing of an epoxy monomer in the presence of an iodonium salt, as photo initiator, is studied. Systems with different concentrations of photo initiators have been polymerized via both gamma rays and e-beam, at various dose rates. The aim of this work is to investigate how the photo initiator concentration and the irradiation dose rate affect the temperature of the systems during curing and how the different thermal histories influence the dynamic mechanical thermal properties of the obtained materials.
The influence of the processing temperature on gamma curing of epoxy resins for the production of advanced composites
2007
Abstract Gamma radiation curing of an epoxy monomer, in the presence of an iodonium salt, as initiator, is studied. Systems have been polymerized at the same irradiation dose and dose rate and at different processing temperatures. The experimental results show that all the irradiated materials exhibit a latent reactivity, undergoing toward an increase of crosslinking density if they are thermally cured after irradiation. The results indicate that the processing temperature affects both the crosslinking density after irradiation and the sensibility to the post-irradiation thermal treatment.
Ultrastrong composites from dopamine modified-polymer-infiltrated colloidal crystals
2015
Although strong and stiff synthetic composites have long been developed, the microstructure of today's most advanced composites has yet to achieve the sophisticated hierarchy of hybrid materials built up by living organisms. We have assembled hard and tough multilayered nanocomposites, which contain alternating layers of Fe3O4 nanoparticles and a 3-hydroxy-tyramine (dopamine) substituted polymer (dopamine modified polymer), strongly cemented together by chelation through infiltration of the polymer into the Fe3O4 mesocrystal. With a Young's modulus of 17 ± 3 GPa and a hardness of 1.3 ± 0.4 GPa the nanocomposite exhibits high resistance against elastic as well as plastic deformation. Key fea…
Thermal properties of e-beam cured epoxy/thermoplastic matrices for advanced composite materials
2007
The aim of this work is to investigate the possibility to improve the thermal behaviour of epoxy based systems, cured by ionizing radiation, in order to produce matrices for advanced carbon fibres composites. Blends of two epoxy monomers, difunctional and trifunctional, have been polymerized by e-beam irradiation and the dynamic mechanical thermal properties have been investigated. The increase of the concentration of the trifunctional epoxy monomer in the blend causes a marked increase of the Tg, but strongly decreases the reactivity. Subsequently, blends of the same epoxy monomers with a high Tg thermoplastic toughening agent have been considered and their reactivity and the thermal prope…