Search results for "composites"
showing 10 items of 1905 documents
Microstructural, mechanical and tribological properties of suspension plasma sprayed YSZ/h-BN composite coating
2018
Abstract Brittleness, relative high friction coefficient and wear rate limit the applications of ceramic coatings as wear-resistant layers. However, because embedding additives with ceramic matrix has demonstrated to be an effective way to improve coating performances, different contents and size of h-BN were added into an YSZ suspension. Afterwards, the YSZ/h-BN composite coatings were manufactured by suspension plasma spray and their tribological analysis indicated that: i) the reduction of the friction coefficient and wear rate can be achieved by incorporating h-BN into YSZ coating. ii) finer h-BN particle is more helpful to enhance the tribological properties of the coating. iii) the op…
Impact behaviour of flax/epoxy composite plates
2015
This paper presents an experimental investigation of the impact behaviour of flax/epoxy composite plates submitted to low-velocity transverse impact. Low energy drop-weight impact tests have been performed on two types of quasi-isotropic flax/epoxy composites, rectangularly shaped with edges lengths of 142 mm × 94 mm and 2.85 mm thick. Residual properties have been assessed by compression after impact tests. A detailed description of damage development, especially the increase of the rear face crack with respect to the impact energy is given by the microscopic observation. The influence of impact damage on the residual strength is described. A loss of 15%–30% in compression resistance was n…
The control of the residual lifetimes of carbon fibre-reinforced composite pressure vessels
2015
International audience; The understanding of the degradation of carbon fibre composites, with emphasis on the use of these composites in filament-wound pressure vessels, is explored. Earlier studies by many researchers have led to a general appreciation of the mechanisms involved; however, only recently have both computational power and experimental techniques become sufficiently developed to allow for the use of quantitative analyses. It is shown that damage is controlled by fibre failure, and that initially this occurs randomly within the structure. In monotonic loading, the development of clusters of fibre breaks causes rapid failure; however, under maintained loads the kinetics of damag…
From fracture to damage mechanics: a behavior law for microcracked composites using the concept of crack opening mode
2010
International audience; Many studies have been carried out in order to build a coherent macroscopic behavior law for a composite containing microcracks. All of them are only partially coherent and none of them is complete. This study proposes a hyperelastic behavior law for a microcracked composite, respecting all the conditions associated with the damage activation/deactivation, stress/strain relation continuity, induced anisotropy and the Clausius–Duhem inequality. This approach is based on the definition of the Crack Opening Mode for Damage Mechanics as it exists in Fracture Mechanics.
Electrospun PCL/GO-g-PEG structures: Processing-morphology-properties relationships
2017
Abstract Polycaprolactone (PCL) biocomposite nanofiber scaffolds with different concentrations of graphene oxide (GO) and GO surface grafted with poly(ethylene glycol) (GO-g-PEG) were prepared by electrospinning. Morphological, mechanical as well as wettability characterizations of electrospun nanofibers were carried out. Results showed that the average diameter of PLA/GO electrospun nanofibers decreased upon increasing the filler content. Differently, the diameter increased while using GO-g-PEG. Both nanofillers enhanced the electrospun PCL hydrophilicity even if PCL/GO-g-PEG samples exhibited improved wettability. The Young moduli of the composite nanofiber mats were improved by adding GO…
Mechanical behavior of polylactic acid/polycaprolactone porous layered functional composites
2016
Abstract Biopolymeric porous devices exhibiting graded properties can play a crucial role in several fields, such as tissue engineering or controlled drugs release. In this context, the gradient of a specific property can be achieved by developing porous laminates composed by different types of materials. This work presents for the first time a multi-phasic porous laminate based on polycaprolactone (PCL) and polylactic acid (PLA) prepared by combining melt mixing, compression molding and particle leaching. All the materials were characterized from a morphological and a mechanical point of view. The results put into evidence the possibility to tune and to predict the mechanical properties by…
Scaffolds based on hyaluronan crosslinked with a polyaminoacid: Novel candidates for tissue engineering application
2008
New porous scaffolds, with a suitable hydrolytic and enzymatic degradation, useful for tissue engineering applications have been obtained by a carbodiimide mediated reaction between hyaluronan (HA) and a synthetic polymer with a polyaminoacid structure such as α,β-polyaspartylhydrazide (PAHy). Scaffolds with a different molar ratio between PAHy repeating units and HA repeating units have been prepared and characterized from a chemical and physicochemical point of view. Tests of indirect and direct cytotoxicity, cell adhesion, and spreading on these biomaterials have been performed by using murine L929 fibroblasts. The new biomaterials showed a good cell compatibility and ability to allow ce…
Numerical simulations of the mechanical characteristics of glass fibre reinforced C-profiles
2006
A mechanical characterisation analysis on pultruded glass fibre reinforced C-shaped profiles, developed as modular construction elements to assemble fastening systems, such as doors, window frames and shutters is presented. The key idea is to perform the analysis, and all the related identification procedures of the material parameters, via a coupled approach, based on a limited number of standard laboratory tests and on the numerical finite element simulations of the same tests. The proposed approach allows one to identify all those material parameters which are difficult to detect, by means of simple laboratory experiments on specimens that are extracted from commercial products. It also …
Bubble formation and motion in non-crimp fabrics with perturbed bundle geometry
2010
The behaviour of the fluid front during impregnation of non-crimp fabrics has been considered. Particular attention is paid to creation of bubbles at the fluid front and a virtual 3D model mimickin ...
Self-organization of porphyrin units induced by magnetic field during sol-gel polymerization
2007
The use of a magnetic field as a controlling factor during the hydrolysis-polycondensation of porphyrin precursors substituted by Si(OR)(3) groups, induces a self-organization of porphyrin moieties due to the stacking of these units in the hybrid material and this study also confirms the effect of the magnetic field in the nano- and micrometric organization during the kinetically controlled polycondensation process.