Aligned discontinuous carbon fibre tows in hybrid composites and their tensile behaviour: An experimental study

2019 ◽  
Vol 53 (26-27) ◽  
pp. 3893-3907
Author(s):  
Khong Wui Gan ◽  
You Wei Ho ◽  
Zheng Yang Ow ◽  
Haris Ahmad Israr ◽  
King Jye Wong

The paper aims to explore potential higher value applications of discontinuous carbon fibre tows. A vibration-assisted dry alignment method is presented to align the discontinuous fibre tows between conventional dry reinforcement mats/fabrics to fabricate cost-effective hybrid composites. Its viability is demonstrated by successful fabrication of two hybrid composite panels, where thin layers of aligned 12 mm discontinuous carbon fibre tows were deposited between E-glass chopped strand mats or woven fabrics respectively, via an out-of-autoclave resin infusion process; 54% and 81% of the fibre tows were aligned in the range of ±5° and ±10°, respectively. The tensile test results clearly demonstrate the importance of having the discontinuous fibre tows highly aligned in the hybrid composites, which shows increased stiffness (up to 24.4%) and strength (up to 59.9%) over the non-aligned hybrid composites. The aligned hybrid composites also exhibit a non-linear pseudo-ductile response due to subcritical progressive damage compared to the catastrophic brittle failure of the baseline non-hybrid E-glass and non-aligned hybrid composites, despite the tensile strength knockdown (up to −40.3%) due to premature inter-tow debonding. They also display increased stiffness up to 90%.

Author(s):  
Yentl Swolfs ◽  
Liesbet Crauwels ◽  
Eline Van Breda ◽  
Larissa Gorbatikh ◽  
Peter Hine ◽  
...  

Author(s):  
V Vignesh Kumar ◽  
K Raja ◽  
T Ramkumar ◽  
M Selvakumar ◽  
TS Senthil Kumar

The research article addresses the reciprocating wear behaviour of hybrid AA7075 reinforced with boron carbide and boron nitride through a stir-casting technique. The experiment involved varying wt.% of the secondary particle boron carbide (3, 6 and 9) while boron nitride (3) was kept as constant. The hybrid composites were characterised using scanning electron microscopy coupled with energy dispersive spectroscopy. The hardness and tensile behaviour of the hybrid composites were evaluated. Reciprocating wear behaviour of the hybrid composites were examined using a tribometer by varying the wear parameters such as load and sliding distance. The results revealed that AA7075/6boron carbide/3boron nitride had better hardness, tensile and wear properties. The surface morphology of the wear samples was analysed using SEM.


Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1178
Author(s):  
Aggelos Koutsomichalis ◽  
Thomas Kalampoukas ◽  
Dionysios E. Mouzakis

The purpose of this study was to manufacture hybrid composites from fabrics with superior ballistic performance, and to analyze their viscoelastic and mechanical response. Therefore, composites in hybrid lay-up modes were manufactured from Vectran, Kevlar and aluminum fiber-woven fabrics through a vacuum assisted resin transfer molding. The specimens were consequently analyzed using static three-point bending, as well as by dynamic mechanical analysis (DMA). Apart from DMA, time–temperature superposition (TTS) analysis was performed by all available models. It was possible to study the intrinsic viscoelastic behavior of hybrid ballistic laminates, with TTS analysis gained from creep testing. A polynomic mathematical function was proposed to provide a high accuracy for TTS curves, when shifting out of the linearity regimes is required. The usual Williams–Landel–Ferry and Arrhenius models proved not useful in order to describe and model the shift factors of the acquired curves. In terms of static results, the highly nonlinear stress–strain curve of both composites was obvious, whereas the differential mechanism of failure in relation to stress absorption, at each stage of deformation, was studied. SEM fractography revealed that hybrid specimens with Kevlar plies are prone to tensile side failure, whereas the hybrid specimens with Vectran plies exhibited high performance on the tensile side of the specimens in three-point bending, leading to compressive failure owing to the high stress retained at higher strains after the maximum bending strength was reached.


Author(s):  
J. Shi

Scatter in test results is common for relatively brittle materials such as ceramic matrix composites. The scatter may come from differences in material processing conditions, specimen machining/handling and from variations in test parameters for nominally the same test material. Large scatter in test results makes material modeling difficult. In the past, master curve concepts have been proposed to reduce scatter in tensile data and to interpret fatigue/creep results. In this paper, one such concept is examined in detail by applying it to the recent tensile test results of a SiC/SiC composite. It was found that the way to construct master curves did not apply to the CMC studied and thus a new master curve was developed to better represent the tensile data. In addition, the test data were analysed statistically based on the new master curve.


2021 ◽  
Vol 168 ◽  
pp. 108293
Author(s):  
Haichao Hu ◽  
Ning Hu ◽  
Qiang Wei ◽  
Boya Liu ◽  
Jin Wu ◽  
...  

Author(s):  
Miss Payal W. Paratpure

Tracking of public bus location requires a GPS device to be installed, and lots of bus operators in developing countries don't have such an answer in situ to supply an accurate estimation of bus time of arrival (ETA). Without ETA information, it's very difficult for the overall public to plan their journey effectively. In this paper, implementation of an innovative IOT solution to trace the real time location of buses without requiring the deployment of a GPS device is discussed. It uses Bluetooth Low Energy (BLE) proximity beacon to trace the journey of a bus by deploying an Estimate location beacon on the bus. BLE detection devices (Raspberry Pi 4) are installed at selected bus stops along the path to detect the arrival of buses. Once detected, the situation of the bus is submitted to a cloud server to compute the bus ETAs. A field trial is currently being conducted in Johor, Malaysia together with an area bus operator on one single path. Our test results showed that the detection of BLE beacons is extremely accurate and it's feasible to trace the situation of buses without employing a GPS device during a cost-effective way.


The present work was planned to evaluate the mechanical properties of alumina reinforced aluminium alloy such hardness and compression behavior of al2o3 /aa7075 alloy metal matrix composites. Both, experimental and finite element analyses were carried out to establish tensile behaviour of the composites with different weight percentage of al2o3 fabricated by the stir casting process. The results concluded that addition of alumina to the aa7075 improves the mechanical properties of the composite. Further the results of FEA simulation of the composites are close to the actual results which shows that cost and time can be reduced if FEA is performed


2021 ◽  
Vol 2021 ◽  
pp. 102-108
Author(s):  
J. Domenech-Pastor ◽  
P. Diaz-Garcia ◽  
D. Garcia

Composites are materials formed by the combination of two or more components that acquire better properties than the ones obtained by each component on its own. Composites have been widely used in the industry due to its light weight and good mechanical properties. To improve these properties several layers of reinforced material (e.g., carbon fibre) are overlapped which produce an increase in the fibre consumption. In this sense Tailored Fibre Placement (TFP) embroidery can offer good opportunity to reduce the consumption of reinforced fibre while improving the mechanical properties due to the alignment of the fibres in the effort direction. This study analyzes the performance of carbon fibre reinforced composites with Polyester resin made with TFP embroidery technology against flexural strength efforts and without using plain woven fabrics to demonstrate that the use of reinforcement fabrics in composites can be optimized by a curved alignment of the fibers. Two different structures were embroidered with TFP technology, one simulating a woven fabric with straight unidirectional alignment of fibres in horizontal and vertical direction, and a second structure made with curvilinear alignment of carbon fibers. After the study of the flexural mechanical properties an improvement of 18% was obtained in maximum flexural strength.


2002 ◽  
Vol 49 (3-4) ◽  
pp. 75-80 ◽  
Author(s):  
Dejan Markovic

Evaluation o f cytotoxicity is a first step in assessment of dental materials biocompatibility. Necessity for unique criteria in researches resulted in international standard methodology (ISO). The aim of this study was to assess the cytotoxicity of four restorative materials (three glas ionomer cements and one composite material) and to define adventages and disadventages of common ISO methodology for evaluation of this aspect of dental materials biocompatibility. Research was designed according to ISO/TC 106/1995 and ISO/ 10993-5/1994 methodology. Materials used in this investigation were Fuji IILC (GC), Vitiemer (3M), Ionosit fill (DMG-Hamburg), Luxat (DMG-Hamburg). Evaluation of cytotoxicity was carried out on standardized Human Diploid Cell Lung WI-38. Obtained results showed expressive cytotoxic effect of all investigated materials without statisticaly significant difference. Estimation of material biocompatibility and assessment of obtained results can be made only after establishment of correlation with test results. Common ISO methodology is simple for conductance and reproduction, and use of cell cultures in researches is painless, cost effective and without moral or ethical dilemma.


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