Abstract: Sisal leaves were subjected to enzymatic retting
method to extract the sisal fibre. A portion of the fibre was pretreated
with alkali (NaOH), and further treated with benzoyl chloride
and silane treatment reagents. Both the treated and untreated Sisal
fibre composites were used to fabricate the composite by hand lay-up
technique using unsaturated polyester resin. Tensile, flexural, water
absorption, density, thickness swelling and chemical resistant tests
were conducted and evaluated on the composites. Results obtained
for all the parameters showed an increase in the treated fibre
compared to untreated fibre. FT-IR spectra results ascertained the
inclusion of benzoyl and silane groups on the fibre surface. Scanning
electron microscopy (SEM) result obtained showed variation in the
morphology of the treated and untreated fibre. Chemical modification
was found to improve adhesion of the fibre to the matrix, as well as
physico-mechanical properties of the composites.
Abstract: The combination of multi–walled carbon nanotubes
(MWCNTs) with polymers offers an attractive route to reinforce the
macromolecular compounds as well as the introduction of new
properties based on morphological modifications or electronic
interactions between the two constituents. As they are only a few
nanometers in dimension, it offers ultra-large interfacial area per
volume between the nano-element and polymer matrix. Nevertheless,
the use of MWCNTs as a rough material in different applications has
been largely limited by their poor processability, insolubility, and
infusibility. Studies concerning the nanofiller reinforced polymer
composites are justified in an attempt to overcome these limitations.
This work presents one preliminary study of MWCNTs dispersion
into the PVDF homopolymer. For preparation, the composite
components were diluted in n,n-dimethylacetamide (DMAc) with
mechanical agitation assistance. After complete dilution, followed by
slow evaporation of the solvent at 60°C, the samples were dried.
Films of about 80 μm were obtained. FTIR and UV-Vis
spectroscopic techniques were used to characterize the
nanocomposites. The appearance of absorption bands in the FTIR
spectra of nanofilled samples, when compared to the spectrum of
pristine PVDF samples, are discussed and compared with the UV-Vis
measurements.
Abstract: A composite material with carbon fiber and polymer
matrix has been used as adherent for manufacturing adhesive joints.
In order to evaluate different fiber orientations on joint performance,
the adherents with the 0°, ±15°, ±30°, ±45° fiber orientations were
used in the single lap joint configuration. The joints with an overlap
length of 25 mm were prepared according to the ASTM 1002
specifications and subjected to tensile loadings. The structural
adhesive used was a two-part epoxy to be cured at 70°C for an hour.
First, mechanical behaviors of the adherents were measured using
three point bending test. In the test, considerations were given to
stress to failure and elastic modulus. The results were compared with
theoretical ones using rule of mixture. Then, the joints were
manufactured in a specially prepared jig, after a proper surface
preparation. Experimental results showed that the fiber orientations
of the adherents affected the joint performance considerably; the
joints with ±45° adherents experienced the worst shear strength, half
of those with 0° adherents, and in general, there was a great
relationship between the fiber orientations and failure mechanisms.
Delamination problems were observed for many joints, which were
thought to be due to peel effects at the ends of the overlap. It was
proved that the surface preparation applied to the adherent surface
was adequate. For further explanation of the results, a numerical
work should be carried out using a possible non-linear analysis.
Abstract: Growth and remodeling of biological structures have
gained lots of attention over the past decades. Determining the
response of living tissues to mechanical loads is necessary for a wide
range of developing fields such as prosthetics design or computerassisted
surgical interventions. It is a well-known fact that biological
structures are never stress-free, even when externally unloaded. The
exact origin of these residual stresses is not clear, but theoretically,
growth is one of the main sources. Extracting body organ’s shapes
from medical imaging does not produce any information regarding
the existing residual stresses in that organ. The simplest cause of such
stresses is gravity since an organ grows under its influence from
birth. Ignoring such residual stresses might cause erroneous results in
numerical simulations. Accounting for residual stresses due to tissue
growth can improve the accuracy of mechanical analysis results. This
paper presents an original computational framework based on gradual
growth to determine the residual stresses due to growth. To illustrate
the method, we apply it to a finite element model of a healthy human
face reconstructed from medical images. The distribution of residual
stress in facial tissues is computed, which can overcome the effect of
gravity and maintain tissues firmness. Our assumption is that tissue
wrinkles caused by aging could be a consequence of decreasing
residual stress and thus not counteracting gravity. Taking into
account these stresses seems therefore extremely important in
maxillofacial surgery. It would indeed help surgeons to estimate
tissues changes after surgery.
Abstract: The application of recycle waste tires into civil
engineering practices, namely asphalt paving mixtures and cementbased
materials has been gaining ground across the world. This
review summarizes and compares the recent achievements in the area
of plain rubberized concrete (PRC), in details. Different treatment
methods have been discussed to improve the performance of
rubberized Portland cement concrete. The review also includes the
effects of size and amount of tire rubbers on mechanical and
durability properties of PRC. The microstructure behaviour of the
rubberized concrete was detailed.
Abstract: Microstructure and mechanical properties of AZ91D
Mg alloys for nonflammable use, containing Ca and Y, were
investigated in this study. Solid solution treatment of AZ91D Mg alloy
with Ca and Y was successfully conducted at 420oC and
supersaturated microstructure with almost all beta phases resolved into
matrix was obtained. After solid solution treatment, the alloy was
annealed at temperatures of 180 and 200oC for time intervals from 1
min to 48 hrs and hardness of each condition was measured by
micro-Vickers method. Peak aging conditions were deduced from the
results as at the temperature of 200oC for 10 hrs. Hot rolling was also
carried out at 400oC by the reduction ratio of 0.6 through 5 passes
followed by recrystallization treatment. Tensile and compressive
properties were measured at room temperature on the specimens of
each process, i.e. as-cast, solution treatment, hot rolling, and
recrystallization.
Abstract: This paper describes an ab-initio design, development and calibration results of an Optical Sensor Ground Reaction Force Measurement Platform (OSGRFP) for gait and geriatric studies. The developed system employs an array of FBG sensors to measure the respective ground reaction forces from all three axes (X, Y and Z), which are perpendicular to each other. The novelty of this work is two folded. One is in its uniqueness to resolve the tri axial resultant forces during the stance in to the respective pure axis loads and the other is the applicability of inherently advantageous FBG sensors which are most suitable for biomechanical instrumentation. To validate the response of the FBG sensors installed in OSGRFP and to measure the cross sensitivity of the force applied in other directions, load sensors with indicators are used. Further in this work, relevant mathematical formulations are presented for extracting respective ground reaction forces from wavelength shifts/strain of FBG sensors on the OSGRFP. The result of this device has implications in understanding the foot function, identifying issues in gait cycle and measuring discrepancies between left and right foot. The device also provides a method to quantify and compare relative postural stability of different subjects under test, which has implications in post-surgical rehabilitation, geriatrics and optimizing training protocols for sports personnel.
Abstract: Some of the main causes for degradation of polymeric materials are thermal aging, hydrolysis, oxidation or chemical degradation by acids, alkalis or water. The first part of this paper provides a brief summary of advances in technology, methods and specification of composite materials for relining as a rehabilitation technique for sewage systems. The second part summarizes an investigation on frequently used composite materials for relining in Sweden, the rubber filled epoxy composite and reinforced polyester composite when they were immersed in deionized water or in dry conditions, and elevated temperatures up to 80°C in the laboratory. The tests were conducted by visual inspection, microscopy, Dynamic Mechanical Analysis (DMA), Differential Scanning Calorimetry (DSC) as well as mechanical testing, three point bending and tensile testing.
Abstract: We have aimed to produce a self-cleaning transparent
polymer coating with polyurethane (PU) matrix as the latter is highly
solvent, chemical and weather resistant having good mechanical
properties. Nano-silica modified by 1H, 1H, 2H, 2Hperflurooctyltriethoxysilane
was incorporated into the PU matrix for
attaining self-cleaning ability through hydrophobicity. The
modification was confirmed by particle size analysis and scanning
electron microscopy (SEM). Thermo-gravimetric (TGA) studies were
carried to ascertain the grafting of silane onto the silica. Several
coating formulations were prepared by varying the silica loading
content and compared to a commercial equivalent. The effect of
dispersion and the morphology of the coated films were assessed by
SEM analysis. All coating standardized tests like solvent resistance,
adhesion, flexibility, acid, alkali, gloss etc. have been performed as
per ASTM standards. Water contact angle studies were conducted to
analyze the hydrophobic character of the coating. In addition, the
coatings were also subjected to salt spray and accelerated weather
testing to analyze the durability of the coating.
Abstract: In this current contribution, authors are dedicated to
investigate influence of the crystal lamellae orientation on
electromechanical behaviors of relaxor ferroelectric Poly
(vinylidene fluoride –trifluoroethylene -chlorotrifluoroethylene)
(P(VDF-TrFE-CTFE)) films by control of polymer microstructure,
aiming to picture the full map of structure-property relationship. In
order to define their crystal orientation films, terpolymer films were
fabricated by solution-casting, stretching and hot-pressing process.
Differential scanning calorimetry, impedance analyzer, and tensile
strength techniques were employed to characterize crystallographic
parameters, dielectric permittivity, and elastic Young’s modulus
respectively. In addition, large electrical induced out-of-plane
electrostrictive strain was obtained by cantilever beam mode.
Consequently, as-casted pristine films exhibited surprisingly high
electrostrictive strain 0.1774% due to considerably small value of
elastic Young’s modulus although relatively low dielectric
permittivity. Such reasons contributed to large mechanical elastic
energy density. Instead, due to 2 folds increase of elastic Young’s
modulus and less than 50% augmentation of dielectric constant, fullycrystallized
film showed weak electrostrictive behavior and
mechanical energy density as well. And subjected to mechanical
stretching process, Film C exhibited stronger dielectric constant and
out-performed electrostrictive strain over Film B because edge-on
crystal lamellae orientation induced by uniaxially mechanical stretch.
Hot-press films were compared in term of cooling rate. Rather large
electrostrictive strain of 0.2788% for hot-pressed Film D in
quenching process was observed although its dielectric permittivity
equivalent to that of pristine as-casted Film A, showing highest
mechanical elastic energy density value of 359.5 J/m3. In hot-press
cooling process, dielectric permittivity of Film E saw values at 48.8
concomitant with ca.100% increase of Young’s modulus. Films with
intermediate mechanical energy density were obtained.
Abstract: Excessive vibration means increased wear, increased
repair efforts, bad product selection & quality and high energy
consumption. This may be sometimes experienced by cavitation or
suction/discharge recirculation which could occur only when net
positive suction head available NPSHA drops below the net positive
suction head required NPSHR. Cavitation can cause axial surging, if it
is excessive, will damage mechanical seals, bearings, possibly other
pump components frequently, and shorten the life of the impeller.
Efforts have been made to explain Suction Energy (SE), Specific
Speed (Ns), Suction Specific Speed (Nss), NPSHA, NPSHR & their
significance, possible reasons of cavitation /internal recirculation, its
diagnostics and remedial measures to arrest and prevent cavitation in
this paper. A case study is presented by the author highlighting that
the root cause of unwanted noise and vibration is due to cavitation,
caused by high specific speeds or inadequate net- positive suction
head available which results in damages to material surfaces of
impeller & suction bells and degradation of machine performance, its
capacity and efficiency too. Author strongly recommends revisiting
the technical specifications of CW pumps to provide sufficient NPSH
margin ratios >1.5, for future projects and Nss be limited to 8500 -
9000 for cavitation free operation.
Abstract: The paper presents an additive manufacturing process for the production of metal and composite parts. It is termed as composite metal foil manufacturing and is a combination of laminated object manufacturing and brazing techniques. The process has been described in detail and is being used to produce dissimilar aluminum to copper foil single lap joints. A three dimensional finite element model has been developed to study the thermo-mechanical characteristics of the dissimilar Al/Cu single lap joint. The effects of thermal stress and strain have been analyzed by carrying out transient thermal analysis on the heated plates used to join the two 0.1mm thin metal foils. Tensile test has been carried out on the foils before joining and after the single Al/Cu lap joints are made, they are subjected to tensile lap-shear test to analyze the effect of heat on the foils. The analyses are designed to assess the mechanical integrity of the foils after the brazing process and understand whether or not the heat treatment has an effect on the fracture modes of the produced specimens.
Abstract: Biodiesel is widely investigated to solve the twin
problem of depletion of fossil fuel and environmental degradation.
The main objective of the present work is to compare performance,
emissions, and combustion characteristics of biodiesel derived from
cotton seed oil in a diesel engine with the baseline results of
petrodiesel fuel. Tests have been conducted on a single cylinder, four
stroke CIDI diesel engine with a speed of 1500 rpm and a fixed
compression ratio of 17.5 at different load conditions. The
performance parameters evaluated include brake thermal efficiency,
brake specific fuel consumption, brake power, indicated mean
effective pressure, mechanical efficiency, and exhaust gas
temperature. Regarding combustion study, cylinder pressure, rate of
pressure rise, net heat release rate, cumulative heat release, mean gas
temperature, mass fraction burned, and fuel line pressure were
evaluated. The emission parameters such as carbon monoxide, carbon
dioxide, un-burnt hydrocarbon, oxides of nitrogen, and smoke
opacity were also measured by a smoke meter and an exhaust gas
analyzer and compared with baseline results. The brake thermal
efficiency of cotton seed oil methyl ester (CSOME) was lower than
that of petrodiesel and brake specific fuel consumption was found to
be higher. However, biodiesel resulted in the reduction of carbon
dioxide, un-burnt hydrocarbon, and smoke opacity at the expense of
nitrogen oxides. Carbon monoxide emissions for biodiesel was higher
at maximum output power. It has been found that the combustion
characteristics of cotton seed oil methyl ester closely followed those
of standard petrodiesel. The experimental results suggested that
biodiesel derived from cotton seed oil could be used as a good
substitute to petrodiesel fuel in a conventional diesel without any
modification.
Abstract: Holistic methods covering the development process as
a whole – e.g. systems engineering – have established themselves in
product design. However, technical product optimization,
representing improvements in efficiency and/or minimization of loss,
usually applies to single components of a system. A holistic approach
is being defined based on a hierarchical point of view of systems
engineering. This is subsequently presented using the example of an
electromechanical flywheel energy storage system for automotive
applications.
Abstract: This paper presents the effects of mixing procedures
on mechanical properties of flyash-based geopolymer matrices
containing nanosilica (NS) at 0.5%, 1.0%, 2.0%, and 3.0% by weight.
Comparison is made with conventional mechanical dry-mixing of NS
with flyash and wet-mixing of NS in alkaline solutions. Physical and
mechanical properties are investigated using X-Ray Diffraction
(XRD) and Scanning Electron Microscope (SEM). Results show that
generally the addition of NS particles enhanced the microstructure
and improved flexural and compressive strengths of geopolymer
nanocomposites. However, samples, prepared using dry-mixing
approach, demonstrate better physical and mechanical properties
comparing to wet-mixing samples.
Abstract: There was a scenario present day that drying of fresh
fruits and vegetables by indirect solar drying by using mechanical
device; hence, an effort was made to develop a small scale solar
tunnel dryer (STD). Drying of spinach is carried out to analyze the
performance of the dryer and to study its drying characteristics. To
evaluate the performance of dryer the independent variables were
selected as air flow rate, loading density and shade net while collector
efficiency, drying efficiency, overall efficiency and specific energy
consumption were selected as responses during performing the
experiments. The spinach was dried from initial moisture content
88.21-94.04% (w.b.) to final moisture content 3.50-5.13% (w.b.). The
drying time considerably reduced as compared to open sun drying of
spinach as sun drying took 15 h for drying. The average collector
efficiency, drying efficiency and overall efficiency were in the range
28.73-61.15%, 11.63% to 22.13%, and 7.61-14.66%, respectively.
Abstract: Bottom ash from Municipal Solid Waste Incineration
(MSWI) can be viewed as a typical granular material because these
industrial by-products result from the incineration of various
domestic wastes. MSWI bottom ash is mainly used in road
engineering in substitution of the traditional natural aggregates. As
the characterization of their mechanical behavior is essential in order
to use them, specific studies have been led over the past few years. In
the first part of this paper, the mechanical behavior of MSWI bottom
ash is studied with triaxial tests. After, analysis of the experiment
results, the simulation of triaxial tests is carried out by using the
software package CESAR-LCPC. As the first approach in modeling
of this new class material, the Mohr-Coulomb model was chosen to
describe the evolution of material under the influence of external
mechanical actions.
Abstract: In India, most of the pavement is laid by bituminous
road and the consumption of binder is high for pavement construction
and also modified binders are used to satisfy any specific pavement
requirement. Since the binders are visco-elastic material which is
having the mechanical properties of binder transition from viscoelastic
solid to visco-elastic fluid. In this paper, two different
protocols were used to measure the viscosity property of binder using
a Brookfield Viscometer and there is a need to find the appropriate
mixing and compaction temperatures of various types of binders
which can result in complete aggregate coating and adequate field
density of HMA mixtures. The aim of this work is to find the
transition temperature from Non-Newtonian behavior to Newtonian
behavior of the binder by adopting a steady shear protocol and the
shear rate ramp protocol. The transition from non-Newtonian to
Newtonian can occur through an increase of temperature and shear of
the material. The test has been conducted for unmodified binder VG
30. The transition temperature was found in the unmodified binder
VG is 120oC. Therefore, the application of both modified binder and
unmodified binder in the pavement construction needs to be studied
properly by considering temperature and traffic loading factors of the
respective project site.
Abstract: Cochlear Implantation (CI) which became a routine
procedure for the last decades is an electronic device that provides a
sense of sound for patients who are severely and profoundly deaf.
The optimal success of this implantation depends on the electrode
technology and deep insertion techniques. However, this manual
insertion procedure may cause mechanical trauma which can lead to
severe destruction of the delicate intracochlear structure.
Accordingly, future improvement of the cochlear electrode implant
insertion needs reduction of the excessive force application during
the cochlear implantation which causes tissue damage and trauma.
This study is examined tool-tissue interaction of large prototype scale
digit embedded with distributive tactile sensor based upon cochlear
electrode and large prototype scale cochlea phantom for simulating
the human cochlear which could lead to small scale digit
requirements. The digit, distributive tactile sensors embedded with
silicon-substrate was inserted into the cochlea phantom to measure
any digit/phantom interaction and position of the digit in order to
minimize tissue and trauma damage during the electrode cochlear
insertion. The digit have provided tactile information from the digitphantom
insertion interaction such as contact status, tip penetration,
obstacles, relative shape and location, contact orientation and
multiple contacts. The tests demonstrated that even devices of such a
relative simple design with low cost have potential to improve
cochlear implant surgery and other lumen mapping applications by
providing tactile sensory feedback information and thus controlling
the insertion through sensing and control of the tip of the implant
during the insertion. In that approach, the surgeon could minimize the
tissue damage and potential damage to the delicate structures within
the cochlear caused by current manual electrode insertion of the
cochlear implantation. This approach also can be applied to other
minimally invasive surgery applications as well as diagnosis and path
navigation procedures.
Abstract: This experimental study consists of a characterization
of epoxy grout where an amount of 2% of graphene nanoplatelets
particles were added to commercial epoxy resin to evaluate their
behavior regarding neat epoxy resin. Compressive tests, tensile tests
and flexural tests were conducted to study the effect of graphene
nanoplatelets on neat epoxy resin. By comparing graphene-based and
neat epoxy grout, there is no significant increase of strength due to
weak interface in the graphene nanoplatelets/epoxy composites.
From this experiment, the tension and flexural strength of graphenebased
epoxy grouts is slightly lower than ones of neat epoxy grout.
Nevertheless, the addition of graphene has produced more consistent
results according to a smaller standard deviation of strength.
Furthermore, the graphene has also improved the ductility of the
grout, hence reducing its brittle behaviour. This shows that the
performance of graphene-based grout is reliably predictable and able
to minimise sudden rupture. This is important since repair design of
damaged pipeline is of deterministic nature.