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This study compares the mechanical, tribological, and dielectric properties of glass fiber-reinforced epoxy (GFRE), presenting various fiber/matrix adhesions. Three GFRE composites were studied. The only difference between them is in the initial preparation of fibers which is intentionally simplified compared to the complex sizings used in industry...
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... mechanical properties Table 3 gives the mechanical properties of the tested composite materials. The flexural longitudinal modulus E L is mainly linked to the volume fraction of fiber that is consistent with the so-called rule of mixtures for a continuous fiber composite, ...
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... the monotonic ultimate properties and the failure mode of the composite materials vary strongly with the nature of the fiber/matrix interface (Table 3). ...
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... hypothesis is rein- forced by impact flexural tests performed at 0.8 mm/s on the two composites. For both materials, the impact strength at break increases with strain rate, but the dif- ference is larger for the material W, for which the strength at break is slightly higher than for the AS material (Table 3). In fact, the glass fibers exhibited rate dependence due to the presence of the surface defects. ...
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... failure features of (AS) or (W) materials are characteristic of UD composites with good enough fiber/matrix adhe- sion. The failure for composite (Si) is specific and char- acteristic of a weakly bonded composite behavior (Table 3). ...
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... results are consistent with ILSS measurements (Table 3). The failure occurs by intensive shear at the neutral plane and this kind of test is very often consid- ered to be a good way to compare the quality of fiber/ matrix adhesion in different composites. ...
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... the dielectric point of view (Table 4 and Figure 3), these two materials have a rather close behavior: evacuation of the charges by release or diffu- sion, which limits the localization of the polarization energy. However, this effect is more significant for com- posite (AS) what leads to higher mechanical properties (Table 3). ...
Citations
... where E is the storage modulus and E is the loss modulus. This method is especially well suited for analysing the relaxation processes ((main or α) and sub-T g ) of polymer-based materials [103][104][105]. DMA tests were carried out using a DMA50 of 01 dB METRAVIB (Limonest, France) on rectangular specimens cut into the clutch facing (size 40 × 12 × 2.5 mm 3 ; see Figure 9a). ...
... This method is especially well suited for analysing the relaxation processes ((mai α) and sub-Tg) of polymer-based materials [103][104][105]. DMA tests were carried out usi DMA50 of 01 dB METRAVIB (Limonest, France) on rectangular specimens cut into clutch facing (size 40 × 12 × 2.5 mm 3 ; see Figure 9a). ...
The clutch facing is a complex organic matrix composite in dry clutch systems. When the clutch engages, there is a sliding contact between the clutch facing and the mating surfaces, resulting in temperature increases of up to 300 °C. These thermal cycles activate several mechanisms that can have consequences on such material: cracking and, more generally, the ageing of the polymer. The thermomechanical properties of the material therefore evolve according to the number of thermal cycles. This study focused on investigating the local and average evolution of the coefficients of thermal expansion (CTE) of clutch facing as a function of thermal cycles. Several techniques were employed, including image stereocorrelation for determining the CTE, Dynamic Mechanical Analysis (DMA) tests for monitoring the ageing of the material and acoustic emission for highlighting the damage. The results showed that the average CTE decreased as a function of the temperature and the number of loading cycles, while locally, it increased in some areas and decreased in others. These differences appear to be the result of material heterogeneity (actual yarn tracing, etc.) and interaction between cracking and ageing mechanisms in the polymer matrix. Indeed, thermal cycling led to cracking and additional crosslinking, which is influenced by ageing conditions.
... The role of fibre-matrix interface and fibre orientation on the dielectric properties of glass fibre-reinforced epoxy composites were studied by Kechaou et al. using the scanning electron microscope mirror effect (SEMME) technique [11]. The SEMME method can be applied to any insulating material, and their ability to trap or diffuse electric charges can be known. ...
Composites with improved electrical properties created new pathways in electrical engineering industries. In this work, electrical studies conducted on continuous unidirectional E-glass fibre-reinforced epoxy composites modified with three different graphite oxide fillers are discussed. The three different fillers are (i) graphite oxide (GO), (ii) exfoliated graphite oxide (EGO), and (iii) reduced exfoliated graphite oxide (rEGO). Incorporation of GO fillers exhibited significant improvement in the dielectric characteristics of the composites, where it showed 42% enhancement in breakdown strength values. Dielectric constant measurements of GO-filled composites have also demonstrated considerable enhancement in the values where the fillers promoted interfacial and dipolar polarization phenomena in the material. On the other hand, in the case of EGO and rEGO fillers, conducting nature induced from graphitic structure had significantly reduced the dielectric properties of their composites.
... A closer look at Fig. 12 explains further on the distribution of the glass fiber into the epoxy matrix as presented by the authors. More so, authors like Lin et al. [109], Kechaou et al. [110], Park et al. [111], Manju et al. [112], Ogaili et al. [113], Kumar et al. [114], Nasif et al. [115], Yanfeng et al. [116], Nagaraj et al. [117], Mohammad et al. [118], and Amin et al. [119] extensively reported on the mechanical, corrosion, and electrical properties of both modified and non-modified glass fiber-reinforced epoxy composites for use in mechanical load-bearing and/or insulator applications (see Table 1). And Figs. 13 and 14 illustrate and explain the electrical behaviour of E-glass fiber-reinforced thermosetting polymers (epoxy and polyester) composites and their exposure to acid/moisture. ...
In recent years, glass fiber-reinforced epoxy composites have been proven to be a promising material for use in fabricating insulator core rods for high-voltage transmission lines. Composite insulator core rods are reportedly degrading during its application due to poor interfacial bonding, brittle fracture, stress corrosion cracking, water absorption, and decay-like fracture. These key factors have affected their mechanical and electrical insulation properties during application. However, this review summarizes the effects of glass fibers, such as E-glass and electrical corrosion resistance glass fiber on the corrosion, mechanical, and electrical properties of epoxy composites for composite insulator core rods. Further, the authors concluded the review with advancement, challenges, and recommendations for future improvement of epoxy composites as a mechanical load-bearing and insulation component material in high-voltage composite insulators. As such, the review offers an intuition into the advancement and selection of glass fiber-reinforced epoxy composite materials for core rods. More so, the review will also give way for further research on insulator core rods development for high-voltage transmission lines.
... Their main advantages are low cost, easy production and friendly to the environment. However, the addition of nano-scale synthetic fillers in nanoparticles can improve the viscosity and rheological properties of the polymer (5)(6). Furthermore, the hybrid composite materials can generate high rheological properties such as specific strength, rigidity and processing (7)(8). ...
This work presents the elaboration, formulation, morphological, viscosimetric and rheological behaviors of epoxy resin NGTHTPTBAE and its composite (NGTHTPTBAE/MDA/TSP). Furthermore, we studied the viscosimetric behavior of epoxy resin NGTHTPTBAE. Then, the rheological behavior of prepared composites (NGTHTPTBAE/MDA/TSP) crosslinked by methylene dianiline (MDA) as hardened and formulated by trisodium phosphate (TSP) as filler at different percentages. Thus, the conservation modulus G' and loss modulus G'' (or tanδ = G''/G') are established according to temperature. From these dependencies, we determined the glass transition temperature or tanδ maximum. Moreover, tan δ > 1 for liquid-like materials and it becomes lower than unity for solid-like materials. Finally, the dispersion of the trisodium phosphate incorporated into various prepared composite (NGTHTPTBAE/MDA/TSP) was determined using the scanning electron microscope (SEM).
... The schemed diagrams of the molecular structures of four original materials were shown in Figure 1a. Figure 1b exhibited their 1 H NMR results. Based on the substantial reports [18,19], the declared chemical compositions for them in Materials and Methods section could be confirmed. The permittivity and dielectric loss for 80-15-5 and 80-15-5/PHBV-20 samples were obtained as a function of frequency in Figure 1c and Figure 1d, respectively. ...
... In comparison to 80-15-5, an introduction of 20 wt % of PHBV would result in a reduction of permittivity, attributed to the dilution effect of PHBV with lower polarity [18]. Based on Figure 1d, dielectric loss of composite was slightly higher than 80-15-5 at lower frequencies, due to the interphase formed between two components (interface-induced leakage-conduction loss) in 80-15-5/PHBV-20 [19]. The composite exhibited a lower loss than 80-15-5 at the frequencies between 10 kHz and 1 MHz. ...
High discharged energy density and charge–discharge efficiency, in combination with high electric breakdown strength, maximum electric displacement and low residual displacement, are very difficult to simultaneously achieve in single-component polymer dielectrics. Plenty of researches have reported polymer based composite dielectrics filled with inorganic fillers, through complex surface modification of inorganic fillers to improve interface compatibility. In this work, a novel strategy of introducing environmentally-friendly biological polyester into fluoropolymer matrix has been presented to prepare all-organic polymer composites with desirable high energy storage properties by solution cast process (followed by annealing or stretching post-treatment), in order to simplify the preparation steps and lower the cost. Fluoropolymer with substantial ferroelectric domains (contributing to high dielectric response) as matrix and poly (3-hydroxybutyrate-co-3-hydroxyvalerate) with excellent linear polarization property (resulting in high breakdown strength) as filler were employed. By high-temperature annealing, the size of ferroelectric domains could be improved and interfacial air defects could be removed, leading to elevated high energy storage density and efficiency in composite. By mono-directional stretching, the ferroelectric domains and polyester could be regularly oriented along stretching direction, resulting in desired high energy storage performances as well. Besides, linear dielectric components could contribute to high efficiency from their strong rigidity restrain effect on ferroelectric component. This work might open up the way for a facile fabrication of promising all-organic composite dielectric films with high energy storage properties.
... The SEMME technique, developed during the 1990s [22,23], can provide information related to the trapping and mobility of electric charges within insulating materials. For fibre-reinforced composites, its use appears to have been limited to studies by Kechaou et al: they have investigated the influence of fibre-matrix interfaces on dielectric behaviour, to determine the mechanical effects of sizing on glass fibres moulded in epoxy resin [24][25][26][27] and drying of hemp fibres moulded in polypropylene [28]. In these studies, the fibre-matrix interface regions were observed to play a major role in the trapping or diffusion of charges, where charge diffusion is associated with high interface strength. ...
... Thus a steeper gradient represents a lower value of Q t , implying that fewer charges are trapped and stabilised; instead, more charges diffuse through the material. For fibre-reinforced PMCs, there is evidence to suggest that diffusion of charges along the fibre-matrix interfaces, as opposed to trapping in these regions, corresponds to higher interfacial shear strength [24][25][26][27][28]. At higher beam voltages, the plot of 1/d versus V becomes non-linear: here, a sub-linear curve indicates a lateral spreading of trapped charges, whereas a super-linear curve implies a deeper dispersion of these charges [24]. ...
... Other SEMME investigations have utilised small parallelepiped samples, typically ∼10 × 10 × 1-5 mm thick [22][23][24][25][26][27]32]. High injection voltages (30 kV) were used for a short duration, up to 200 ms [23][24][25][26][27][28], though longer injection times (10-20 s), at lower voltages (< 19 kV) have also been employed [32]. ...
A viscoelastically prestressed polymeric matrix composite (VPPMC) is produced by applying tensile creep to polymeric fibres, the creep load being removed before the fibres are moulded into a resin matrix. Following matrix curing, the viscoelastically strained fibres impart compressive stresses to the surrounding matrix, counterbalanced by residual tension in the fibres. VPPMCs based on nylon 6,6 fibres in polyester resin have previously demonstrated improvements in mechanical properties of up to 50% compared with control (unstressed) counterparts. Although the associated viscoelastic recovery forces are understood, little is known of the fibre-matrix interactions relating to prestress within VPPMCs. This is addressed by investigating composite samples with the scanning electron microscope mirror effect (SEMME). By comparing results from VPPMC samples with their control counterparts, the findings suggest that there are ∼30% fewer trapped negative charges in the former, implying that the VPPMCs possess higher fibre-matrix interfacial strengths. Tensile test results on similar composite samples support these findings. The effects of resin porosity in SEMME data are also evaluated and our findings suggest that porosity can significantly increase charge trapping.
... Nowadays, studies on investigating the RAS using fiber reinforced polymeric composite materials are becoming popular research field. 3,4 Since the mechanical properties and dielectric properties of carbon fiber reinforced polymeric composites (CFRP) can be tailored effectively, they are plausible materials for fabricating the RAS of desired performance. 3,5,6 Usually, the carbon fibers with noncircular-shapes are used in the RAS to enhance the absorbing property of the carbon fiber reinforced polymeric composites. ...
Triangle-shape carbon fiber reinforced polymeric composites is a plausible material for fabricating the radar absorbing structure. In order to design the effective electromagnetic wave absorber, the dielectric properties of its constituents are required in the target frequency band. In this paper, the unidirectional triangle-shape carbon fiber/epoxy composites were manufactured and the carbon fiber volume fraction of composite materials was measured to be about 46%. And then the permittivities of specimens were tested with the rectangle waveguide method in the vertical direction and in the parallel direction. The theoretical models and prediction equations for estimating permittivity of the unidirectional triangle-shape carbon fiber/epoxy composites were proposed with respect to the fiber volume fractions, the cross-section shape of fiber, the fiber orientations and the permittivity of components. It was found that the theoretical values agreed well with the experimental results.
... The concept of developing special materials and coatings to overcome friction and wear problems has become a reality in the recent material developing world. Metal matrix composites (MMCs) are potential materials used for technological applications because they exhibit better mechanical, 1 thermal 2 and tribological, 3 properties as compared to the conventional metal alloys. The aim behind designing MMC materials is to combine the desirable attributes of the metals and the ceramics. ...
... As a result, the delamination of MML occurs. The wear loss is in the form of chips coming out from the material and oxidative layer [1][2][3][4][5][6][7][8][9][10][11] //blrnas3/cenpro/ApplicationFiles/Journals/SAGE/3B2/JCMJ/Vol00000/140035/APPFile/SG-JCMJ140035.3d (JCM) [PREPRINTER stage] no longer has the capability to withstand high stress due to load and thermal softening. ...
... [1][2][3][4][5][6][7][8][9][10][11] //blrnas3/cenpro/ApplicationFiles/Journals/SAGE/3B2/JCMJ/Vol00000/140035/APPFile/SG-JCMJ140035.3d (JCM) [PREPRINTER stage] ...
In the present investigations, LM13 aluminium alloy reinforced with 15 and 20wt.% rutile mineral of fine (50-75 µm) and coarse (106-125 µm) size range was prepared through stir casting technique. The microhardness on different phase of the composite was measured to check the interfacial bonding of particles with the base material. The wear properties of the samples were studied using pin-on-disc tribometer at high load (49 N) with variation in temperatures from 50℃ to 300℃. Wear results indicated that the composites containing fine size reinforced particles showed around two times higher wear resistance over a wide range of temperature than the composite-containing coarse particles. A transition in wear mode from mild to severe was observed above 200℃. Wear track and wear debris were analysed to understand the nature of wear.
... Aging phenomenon in high voltage insulation was found to be strongly related to the matrix/fiber bonding efficiency, surface treated glass fibers with suitable sizing behave better than untreated fibers [20]. Improved dielectric behavior has also been reported on composites, where the fiber had been treated with an amino-silane coupling agent [21]. ...
The latest generation of fusion devices needs large superconducting magnets that have to withstand operational voltages of tens of kV. Their insulation typically targets a dielectric strength of about 10 times the operational voltages to cope with degradation during operation resulting from the high electromagnetic loads with cyclic components, thermal stresses due to cycles from 293 K to 4 K, and ionizing radiation. Degradation of dielectric strength is further mitigated by applying solid polyimide overlapped layers in the insulation. The level of Lorentz forces, together with the large superconducting coil sizes, makes high-voltage tests impossible to realize under exact operational conditions. The fact that insulation is very difficult or even often practically impossible to repair in case of electrical fault, requires sound insulation design to reach utmost quality. In this paper, we will discuss the build-up of the electrical insulation in large superconducting magnets both from the manufacturing and operational point of view. In particular, the impact of the insulation design and manufacturing choices on the quality will be discussed in depth. We will also discuss the implementation and the application of insulation systems.
... L'endommagement associé à la projection de particules peut avoir lieu dans trois différentes phases du matériau: la matrice, l'interface fibre/matrice et les fibres (Soboyejo 2003) Dans le cas des composites ayant un caractère anisotrope marqué en surface (stratifiés réalisés à partir de nappe UD ou composites injectés avec une orientation préférentielle en surface), le comportement à l'abrasion est très dépendant de l'orientation des fibres par rapport à la sollicitation (Pool 1986 ; ; Tewari2002) comme dans le cas du fretting wear (Turki 2004 ;Kechaou 2011). La rupture et la fragmentation des fibres sont favorisées lorsque l'impact du jet de particules a lieu perpendiculairement à la direction principale des fibres (fléchissement des fibres), c'est-à-dire soit pour une incidence normale du faisceau de particules soit si l'angle d'attaque est différent de 90° et que la projection a lieu perpendiculairement aux fibres. ...
One of most problematic in the aeronautical industries is the structural joining of the high performance thermoplastic composites like PEEK composites. Actually, a lot of technologies are used for joining thermoplastic composites like welding, bolting, riveting, fastening and adhesive bonding. Due to the various advantages that characterize the adhesive bonding method, such an uniform stress distribution along the joint, weight-light and cost reduction, makes this technique more desirable to join thermoplastic composites materials compared to the other joining techniques.
PEEK (PolyEtherEtherKetone) is a semi-crystalline thermoplastic material with high performance. This material is wildly used in aeronautical industries, principally, reinforced with carbon of glass fibres. However, its high chemical resistance makes the adhesive bonding of PEEK and its composites difficult and therefore an appropriate and optimised surface treatment is necessary. In the aim to obtain a bonded system with high performance, scientific and technical problematic should be focussed on the junction between adherents. Indeed, the quality of this junction is of utmost importance because it must allow optimum transfer of thermo-mechanical stresses when the assembly is subject to its terms of use. Though, at this time it is well known that thermoplastic composite materials are difficult to bond with-out surface treatment.
This study, therefore, relates to the improvement of mechanical properties (monotonic and cyclic) of the adhesive bonding system PEEK / PEEK. In this context, a surface treatment, easy to implement, is proposed. This surface treatment is sandblasting, which enables surface topographic (morphological) modifications. Understanding of various phenomena of interfaces interaction involved in the improvement of the mechanical behavior of the adhesive joint and is part of the triptych "Rheology, Physico-chemistry and topography" is the major scientific challenge in this thesis.
Initially, the influence of processing parameters such as the projection time, the particle size on surface morphology of various materials based on PEEK was analyzed, thus allowing establishing the correlation between morphological parameters and modification mechanisms involved during surface treatment surface.
One of the key factors for understanding the mechanisms of interaction between the liquid adhesive and the solid substrate is wettability. The analysis of the wetting behavior as a function of various parameters of the treatment was performed. The wettability of treated surfaces is strongly affected by surface roughness created after this treatment. The relationship between morphological parameters and wettability was discussed.
Finally, the influence of sandblasting processing parameters on the mechanical behavior in monotoning and long-term (fatigue tests) of the adhesive joint strength was studied, using single lap shear tests specimens. This has led to the proposal of specific surface morphological parameters for the optimization of the mechanical behavior of the adhesive joint of PEEK and its composites.
