Abstract: In the competitive environment of aircraft industries it becomes absolutely necessary to improve the efficiency, performance of the aircrafts to reduce the development and operating costs considerably, in order to capitalize the market. An important contribution to improve the efficiency and performance can be
achieved by decreasing the aircraft weight through considerable
usage of composite materials in primary aircraft structures. In this study, a type of composite material called Carbon Fiber Reinforced
Plastic (CFRP) is explored for the usage is aircraft skin panels. Even
though there were plenty of studies and research has been already
carried out, here a practical example of an aircraft skin panel is taken
and substantiated the benefits of composites material usage over the
metallic skin panel. A crown skin panel of a commercial aircraft is
designed using both metal and composite materials. Stress analysis
has been carried out for both and margin of safety is estimated for the
critical load cases. The skin panels are compared for manufacturing,
tooling, assembly and cost parameters. Detail step by step comparison between metal and composite constructions are studied
and results are tabulated for better understanding.
Abstract: The nanofiber sheet of Multiwall Cabon Nanotube
(MWCNTs)/Polyacylonitile (PAN) composites was fabricated from
electrospun nanofiber. Firstly the surface of MWCNTs was
chemically modified, comparing two different techniques consisting
of admicellar polymerization and functionalization to improve the
dispersion and prevent the aggregation in the PAN matrix. The
modified MWCNTs were characterized by the dispersion in
dimethylformamide (DMF) solvent, Laser particle size, and FTRaman.
Lastly, DSC, SEM and mechanical properties of the
nanofiber sheet were examined. The results show that the mechanical
properties of the nanofiber sheet prepared from admicellar
polymerization-modified MWCNTs were higher than those of the
others.
Abstract: The mechanical properties including flexural and
tensile of neat vinyl ester and polymer based on layered silicate
nanocomposite materials are discussed. The addition of layered
silicate into the polymer matrix increased the tensile and flexural
modulus up to 1 wt.% clay loading. The incorporation of more clay
resulted in decreasing the mechanical properties which was traced to
the existence of aggregation layers. Likewise, up to 1 wt.% clay
loading, the thermal behaviour showed significant improvements and
at higher clay loading the thermal pattern was reduced. The
aggregation layers imparted a negative impact on the overall
mechanical and thermal properties. Wide Angle X-ray Diffraction,
Scanning Electron Microscopy and Transmission Electron
Microscopy were utilised in order to characterise the interlamellar
structure of nanocomposites.
Abstract: An advanced composite flywheel rotor consisting of
intra and inter hybrid rims was designed to optimally increase the energy capacity, and was manufactured using filament winding with
in-situ curing. The flywheel has recently attracted considerable attention from many investigators since it possesses great potential in
many energy storage applications, including electric utilities, hybrid or
electric automobiles, and space vehicles. In this investigation, a comprehensive study was conducted with the intent to implement
composites in high performance flywheel applications.The inner two
intra-hybrid rims (rims 1 and 2) were manufactured as a whole part
through continuous filament winding under in-situ curing conditions,
and so were the outer two rims (rims 3 and 4). The outer surface of rim
2 and the inner surface of rim 3 were CNC-tapered for press-fitting. Machined rims were finally press-fitted using a hydraulic press with a
maximum compressive force of approximately 1000 ton.
Abstract: The article presents findings from the study and
analysis of the results of an experimental programme focused on the
production of concrete and fibre reinforced concrete in which natural
aggregate has been substituted with brick or concrete recyclate. The
research results are analyzed to monitor the effect of mechanicalphysical
characteristics on the durability properties of tested
cementitious composites. The key parts of the fibre reinforced
concrete mix are the basic components: aggregates – recyclate,
cement, fly ash, water and fibres. Their specific ratios and the
properties of individual components principally affect the resulting
behaviour of fresh fibre reinforced concrete and the characteristics of
the final product. The article builds on the sources dealing with the
use of recycled aggregates from construction and demolition waste in
the production of fibre reinforced concrete. The implemented
procedure of testing the composite contributes to the building
sustainability in environmental engineering.
Abstract: The present work consecutively on synthesis and
characterization of composites, Al/Al alloy A 384.1 as matrix in
which the main ingredient as Al/Al-5% MgO alloy based metal
matrix composite. As practical implications the low cost processing
route for the fabrication of Al alloy A 384.1 and operational
difficulties of presently available manufacturing processes based in
liquid manipulation methods. As all new developments, complete
understanding of the influence of processing variables upon the final
quality of the product. And the composite is applied comprehensively
to the acquaintance for achieving superiority of information
concerning the specific heat measurement of a material through the
aid of thermographs. Products are evaluated concerning relative
particle size and mechanical behavior under tensile strength.
Furthermore, Taguchi technique was employed to examine the
experimental optimum results are achieved, owing to effectiveness of
this approach.
Abstract: The ever growing sentiment of environmentalism across the globe has made many people think on the green lines. But most of such ideas halt short of implementation because of the short term economic viability issues with the concept of going green. In this paper we have tried to amalgamate the green concept with social entrepreneurship for solving a variety of issues faced by the society today. In addition the paper also tries to ensure that the short term economic viability does not act as a deterrent. The paper comes up three sustainable models of social entrepreneurship which tackle a wide assortment of issues such as nutrition problem, land problems, pollution problems and employment problems. The models described fall under the following heads: - Spirulina cultivation: The model addresses nutrition, land and employment issues. It deals with cultivation of a blue green alga called Spirulina which can be used as a very nutritious food. Also, the implementation of this model would bring forth employment to the poor people of the area. - Biocomposites: The model comes up with various avenues in which biocomposites can be used in an economically sustainable manner. This model deals with the environmental concerns and addresses the depletion of natural resources. - Packaging material from empty fruit bunches (EFB) of oil palm: This one deals with air and land pollution. It is intended to be a substitute for packaging materials made from Styrofoam and plastics which are non-biodegradable. It takes care of the biodegradability and land pollution issues. It also reduces air pollution as the empty fruit bunches are not incinerated. All the three models are sustainable and do not deplete the natural resources any further. This paper explains each of the models in detail and deals with the operational/manufacturing procedures and cost analysis while also throwing light on the benefits derived and sustainability aspects.
Abstract: The dominant judgment for earthquake damaged reinforced concrete (RC) structures is to rebuild them with the new ones. Consequently, this paper estimates if there is chance to repair earthquake RC beams and obtain economical contribution to modern day society. Therefore, the totally damaged (damaged in shear under cyclic load) reinforced concrete (RC) beams repaired and strengthened by externally bonded carbon fibre reinforced polymer (CFRP) strips in this study. Four specimens, apart from the reference beam, were separated into two distinct groups. Two experimental beams in the first group primarily tested up to failure then appropriately repaired and strengthened with CFRP strips. Two undamaged specimens from the second group were not repaired but strengthened by the identical strengthening scheme as the first group for comparison. This study studies whether earthquake damaged RC beams that have been repaired and strengthened will validate similar strength and behavior to equally strengthened, undamaged RC beams. Accordingly, a strength correspondence according to strengthened specimens was acquired for the repaired and strengthened specimens. Test results confirmed that repair and strengthening, which were estimated in the experimental program, were effective for the specimens with the cracking patterns considered in the experimental program.
Abstract: In this study, an ablation, mechanical and thermal properties of a rocket motor insulation from phenolic/ fiber matrix composites forming a laminate with different fiber between fiberglass and locally available synthetic fibers. The phenolic/ fiber matrix composites was mechanics and thermal properties by means of tensile strength, ablation, TGA and DSC. The design of thermal insulation involves several factors.Determined the mechanical properties according to MIL-I-24768: Density >1.3 g/cm3, Tensile strength >103 MPa and Ablation
Abstract: In this study the effect of incorporation of recycled
glass-fibre reinforced polymer (GFRP) waste materials, obtained by
means of milling processes, on mechanical behaviour of polyester
polymer mortars was assessed. For this purpose, different contents of
recycled GFRP waste powder and fibres, with distinct size gradings,
were incorporated into polyester based mortars as sand aggregates
and filler replacements. Flexural and compressive loading capacities
were evaluated and found better than unmodified polymer mortars.
GFRP modified polyester based mortars also show a less brittle
behaviour, with retention of some loading capacity after peak load.
Obtained results highlight the high potential of recycled GFRP waste
materials as efficient and sustainable reinforcement and admixture for
polymer concrete and mortars composites, constituting an emergent
waste management solution.
Abstract: Exploding concentrated underwater charges to
damage underwater structures such as ship hulls is a part of naval
warfare strategies. Adding small amounts of foreign particles (like
clay or silica) of nanosize significantly improves the engineering
properties of the polymers. In the present work the clay in terms 1, 2
and 3 percent by weight was surface treated with a suitable silane
agent. The hybrid nanocomposite was prepared by the hand lay-up
technique. Mathematical regression models have been employed for
theoretical prediction. This will result in considerable savings in terms of project time, effort and cost.
Abstract: Commercial hydroxyapatite (HA) was reinforced by
adding 2, 5, and 10 wt % of 28.5%CaO-28.5%P2O5-38%Na2 O-
5%CaF2 based glass and then sintered. Although HA shows good
biocompatibility with the human body, its applications are limited to
non load-bearing areas and coatings due to its poor mechanical
properties. These mechanical properties can be improved
substantially with addition of glass ceramics by sintering. In this
study, the effects of sintering hydroxyapatite with above specified
phosphate glass additions are quantified. Each composition was
sintered over a range of temperatures. Scanning electron microscopy
and x-ray diffraction were used to characterize the microstructure and
phases of the composites. The density, microhardness, and
compressive strength were measured using Archimedes Principle,
Vickers Microhardness Tester (at 0.98 N), and Instron Universal
Testing Machine (cross speed of 0.5 mm/min) respectively. These
results were used to indicate which composition provided suitable
material for use in hard tissue replacement. Composites containing 10
wt % glass additions formed dense HA/TCP (tricalcium phosphate)
composite materials possessing good compressive strength and
hardness than HA. In-vitro bioactivity was assessed by evaluating
changes in pH and Ca2+ ion concentration of SBF-simulated body
fluid on immersion of these composites in it for two weeks.
Abstract: In this study, hydroxyapatite (HA) composites are
prepared on addition of 30%CaO-30%P2O5-40%Na2 O based glass to
pure HA, in proportion of 2, 5, and 10 wt %. Each composition was
sintered over a range of temperatures. The quantitative phase
analysis was carried out using XRD and the microstructures were
studied using SEM. The density, microhardness, and compressive
strength have shown increase with the increasing amount of glass
addition. The resulting composites have chemical compositions that
are similar to the inorganic constituent of the mineral part of bone,
and constitutes trace elements like Na. X-ray diffraction showed no
decomposition of HA to secondary phases, however, the glass
reinforced-HA composites contained a HA phase and variable
amounts of tricalcium phosphate phase, depending on the amount of
bioglass added. The HA-composite material exhibited higher
compressive strength compared to sintered HA. The HA composite
reinforced with 10 wt % bioglass showed highest bioactivity level.
Abstract: Alkali treated oil palm empty fruit bunch (EFB) fibres
(TEFBF) and untreated EFBF fibers (UEFBF) were incorporated in
polypropylene (PP) with and without malic anhydride grafted PP
(MAPP) and magnesium hydroxide as flame retardant (FR) to
produce TEFBF-PP and UEFBF-PP composites by the melt casting
method. The composites were characterized by mechanical and
burning tests along with a scanning electron microscope and Fourier
transform infrared spectroscopy. The significant improvement in
flexural modulus (133%) and flame retardant property (60%) of
TEFBF-PP composite with MAPP and FR is observed. The improved
mechanical property is discussed by the development of encapsulated
textures.
Abstract: This paper describes a study of geometrically
nonlinear free vibration of thin circular functionally graded (CFGP)
plates resting on Winkler elastic foundations. The material properties
of the functionally graded composites examined here are assumed to
be graded smoothly and continuously through the direction of the
plate thickness according to a power law and are estimated using the
rule of mixture. The theoretical model is based on the classical Plate
theory and the Von-Kármán geometrical nonlinearity assumptions.
An homogenization procedure (HP) is developed to reduce the
problem considered here to that of isotropic homogeneous circular
plates resting on Winkler foundation. Hamilton-s principle is applied
and a multimode approach is derived to calculate the fundamental
nonlinear frequency parameters which are found to be in a good
agreement with the published results. On the other hand, the
influence of the foundation parameters on the nonlinear fundamental
frequency has also been analysed.
Abstract: An aqueous methanol sensor for use in direct
methanol fuel cells (DMFCs) applications is demonstrated; the
methanol sensor is built using dispersed single-walled carbon
nanotubes (SWCNTs) with Nafion117 solution to detect the methanol
concentration in water. The study is aimed at the potential use of the
carbon nanotubes array as a methanol sensor for direct methanol fuel
cells (DMFCs). The concentration of methanol in the fuel circulation
loop of a DMFC system is an important operating parameter, because
it determines the electrical performance and efficiency of the fuel cell
system. The sensor is also operative even at ambient temperatures
and responds quickly to changes in the concentration levels of the
methanol. Such a sensor can be easily incorporated into the methanol
fuel solution flow loop in the DMFC system.
Abstract: Toughening of polyamide 6 (PA6)/ Nanoclay (NC) nanocomposites with styrene-ethylene/butadiene-styrene copolymer (SEBS) using maleated styrene-ethylene/butadiene-styrene copolymer (mSEBS)/ as a compatibilizer were investigated by blending them in a co-rotating twin-screw extruder. Response surface method of experimental design was used for optimizing the material and processing parameters. Effect of four factors, including SEBS, mSEBS and NC contents as material variables and order of mixing as a processing factor, on toughness of hybrid nanocomposites were studied. All the prepared samples showed ductile behavior and low temperature Izod impact toughness of some of the hybrid nanocomposites demonstrated 900% improvement compared to the PA6 matrix while the modulus showed maximum enhancement of 20% compared to the pristine PA6 resin.
Abstract: With the development of the Polyvinyl chloride
(PVC) products in many applications, the challenge of investigating
the raw material composition and reducing the cost have both
become more and more important. Considerable research has been
done investigating the effect of additives on the PVC products. Most
of the PVC composites research investigates only the effect of
single/few factors, at a time. This isolated consideration of the input
factors does not take in consideration the interaction effect of the
different factors. This paper implements a mixture experimental
design approach to find out a cost-effective PVC composition for the
production of electrical-insulation cables considering the ASTM
Designation (D) 6096. The results analysis showed that a minimum
cost can be achieved through using 20% virgin PVC, 18.75%
recycled PVC, 43.75% CaCO3 with participle size 10 microns, 14%
DOP plasticizer, and 3.5% CPW plasticizer. For maximum UTS the
compound should consist of: 17.5% DOP, 62.5% virgin PVC, and
20.0% CaCO3 of particle size 5 microns. Finally, for the highest
ductility the compound should be made of 35% virgin PVC, 20%
CaCO3 of particle size 5 microns, and 45.0% DOP plasticizer.
Abstract: In the present work, we have developed a symmetric electrochemical capacitor based on the nanostructured iron oxide (Fe3O4)-activated carbon (AC) nanocomposite materials. The physical properties of the nanocomposites were characterized by Scanning Electron Microscopy (SEM) and Brunauer-Emmett-Teller (BET) analysis. The electrochemical performances of the composite electrode in 1.0 M Na2SO3 and 1.0 M Na2SO4 aqueous solutions were evaluated using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The composite electrode with 4 wt% of iron oxide nanomaterials exhibits the highest capacitance of 86 F/g. The experimental results clearly indicate that the incorporation of iron oxide nanomaterials at low concentration to the composite can improve the capacitive performance, mainly attributed to the contribution of the pseudocapacitance charge storage mechanism and the enhancement on the effective surface area of the electrode. Nevertheless, there is an optimum threshold on the amount of iron oxide that needs to be incorporated into the composite system. When this optimum threshold is exceeded, the capacitive performance of the electrode starts to deteriorate, as a result of the undesired particle aggregation, which is clearly indicated in the SEM analysis. The electrochemical performance of the composite electrode is found to be superior when Na2SO3 is used as the electrolyte, if compared to the Na2SO4 solution. It is believed that Fe3O4 nanoparticles can provide favourable surface adsorption sites for sulphite (SO3 2-) anions which act as catalysts for subsequent redox and intercalation reactions.
Abstract: Composites based on a biodegradable polycaprolactone (PCL) containing 0.5, 1.0 and 2.0 wt % of titanium dioxide (TiO2) micro and nanoparticles were prepared by melt mixing and the effect of filler type and contents on the thermal properties, dynamic-mechanical behaviour and morphology were investigated. Measurements of storage modulus and loss modulus by dynamic mechanical analysis (DMA) showed better results for microfilled PCL/TiO2 composites than nanofilled composites, with the same filler content. DSC analysis showed that the Tg and Tc of micro and nanocomposites were slightly lower than those of neat PCL. The crystallinity of the PCL increased with the addition of TiO2 micro and nanoparticles; however, the cc for the PCL was unchanged with micro TiO2 content. The thermal stability of PCL/TiO2 composites were characterized using thermogravimetric analysis (TGA). The initial weight loss (5 wt %) occurs at slightly higher temperature with micro and nano TiO2 addition and with increasing TiO2 content.