Abstract: In the process of polyethylene extrusion polymer
material similar to powder or granule is under compression, melting
and transmission operation and on base of special form, extrudate has
been produced. Twin-screw extruders are applicable in industries
because of their high capacity. The powder mixing with chemical
additives and melting with thermal and mechanical energy in three
zones (feed, compression and metering zone) and because of gear
pump and screw's pressure, converting to final product in latest plate.
Extruders with twin-screw and short distance between screws are
better than other types because of their high capacity and good
thermal and mechanical stress.
In this paper, process of polyethylene extrusion and various tapes
of extruders are studied. It is necessary to have an exact control on
process to producing high quality products with safe operation and
optimum energy consumption.
The granule size is depending on granulator motor speed. Results
show at constant feed rate a decrease in granule size was found whit
Increase in motor speed. Relationships between HDPE feed rate and
speed of granulator motor, main motor and gear pump are calculated
following as:
x = HDPE feed flow rate, yM = Main motor speed
yM = (-3.6076e-3) x^4+ (0.24597) x^3+ (-5.49003) x^2+ (64.22092)
x+61.66786 (1)
x = HDPE feed flow rate, yG = Gear pump speed
yG = (-2.4996e-3) x^4+ (0.18018) x^3+ (-4.22794) x^2+ (48.45536)
x+18.78880 (2)
x = HDPE feed flow rate, y = Granulator motor speed
10th Degree Polynomial Fit: y = a+bx+cx^2+dx^3... (3)
a = 1.2751, b = 282.4655, c = -165.2098,
d = 48.3106, e = -8.18715, f = 0.84997
g = -0.056094, h = 0.002358, i = -6.11816e-5
j = 8.919726e-7, k = -5.59050e-9
Abstract: In this study, effects of EGR on CO and HC emissions
of a dual fuel HCCI-DI engine are investigated. Tests were
conducted on a single-cylinder variable compression ratio (VCR)
diesel engine with compression ratio of 17.5. Premixed gasoline is
provided by a carburetor connected to intake manifold and equipped
with a screw to adjust premixed air-fuel ratio, and diesel fuel is
injected directly into the cylinder through an injector at pressure of
250 bars. A heater placed at inlet manifold is used to control the
intake charge temperature. Optimal intake charge temperature was
110-115ºC due to better formation of a homogeneous mixture
causing HCCI combustion. Timing of diesel fuel injection has a great
effect on stratification of in-cylinder charge in HCCI combustion.
Experiments indicated 35 BTDC as the optimum injection timing.
Coolant temperature was maintained 50ºC during the tests. Results
show that increasing engine speed at a constant EGR rate leads to
increase in CO and UHC emissions due to the incomplete
combustion caused by shorter combustion duration and less
homogeneous mixture. Results also show that increasing EGR
reduces the amount of oxygen and leads to incomplete combustion
and therefore increases CO emission due to lower combustion
temperature. HC emission also increases as a result of lower
combustion temperatures.
Abstract: This research was to evaluate a technical feasibility of
making single-layer experimental particleboard panels from bamboo
waste (Dendrocalamus asper Backer) by converting bamboo into
strips, which are used to make laminated bamboo furniture. Variable
factors were density (600, 700 and 800 kg/m3) and temperature of
condition (25, 40 and 55 °C). The experimental panels were tested for
their physical and mechanical properties including modulus of
elasticity (MOE), modulus of rupture (MOR), internal bonding
strength (IB), screw holding strength (SH) and thickness swelling
values according to the procedures defined by Japanese Industrial
Standard (JIS). The test result of mechanical properties showed that
the MOR, MOE and IB values were not in the set criteria, except the
MOR values at the density of 700 kg/m3 at 25 °C and at the density
of 800 kg/m3 at 25 and 40 °C, the IB values at the density of 600
kg/m3, at 40 °C, and at the density of 800 kg/m3 at 55 °C. The SH
values had the test result according to the set standard, except with
the density of 600 kg/m3, at 40 and 55 °C. Conclusively, a valuable
renewable biomass, bamboo waste could be used to manufacture
boards.
Abstract: In this research work, poly (acrylonitrile-butadienestyrene)/
polypropylene (ABS/PP) blends were processed by melt
compounding in a twin-screw extruder. Upgrading of the thermal
characteristics of the obtained materials was attempted by the
incorporation of organically modified montmorillonite (OMMT), as
well as, by the addition of two types of compatibilizers;
polypropylene grafted with maleic anhydride (PP-g-MAH) and ABS
grafted with maleic anhydride (ABS-g-MAH). The effect of the
above treatments was investigated separately and in combination.
Increasing the PP content in ABS matrix seems to increase the
thermal stability of their blend and the glass transition temperature
(Tg) of SAN phase of ABS. From the other part, the addition of ABS
to PP promotes the formation of its β-phase, which is maximum at 30
wt% ABS concentration, and increases the crystallization temperature
(Tc) of PP. In addition, it increases the crystallization rate of PP.The
β-phase of PP in ABS/PP blends is reduced by the addition of
compatibilizers or/and organoclay reinforcement. The incorporation
of compatibilizers increases the thermal stability of PP and reduces
its melting (ΔΗm) and crystallization (ΔΗc) enthalpies. Furthermore it
decreases slightly the Tgs of PP and SAN phases of ABS/PP blends.
Regarding the storage modulus of the ABS/PP blends, it presents a
change in their behavior at about 10°C and return to their initial
behavior at ~110°C. The incorporation of OMMT to no compatibilized
and compatibilized ABS/PP blends enhances their storage modulus.
Abstract: To determine the length of engagement threads of a bolt installed in a tapped part in order to avoid the threads stripping remains a very current problem in the design of the thread assemblies. It does not exist a calculation method formalized for the cases where the bolt is screwed directly in a ductile material. In this article, we study the behavior of the threads stripping of a loaded assembly by using a modelling by finite elements and a rupture criterion by damage. This modelling enables us to study the different parameters likely to influence the behavior of this bolted connection. We study in particular, the influence of couple of materials constituting the connection, of the bolt-s diameter and the geometrical characteristics of the tapped part, like the external diameter and the length of engagement threads. We established an experiments design to know the most significant parameters. That enables us to propose a simple expression making possible to calculate the resistance of the threads whatever the metallic materials of the bolt and the tapped part. We carried out stripping tests in order to validate our model. The estimated results are very close to those obtained by the tests.
Abstract: The influence of full-fat soy flour (FFSF) and
extrusion conditions on the mechanical characteristics of dry
spaghetti were evaluated. Process was performed with screw speed of
10-40rpm and water circulating temperature of 35-70°C. Data
analysis using mixture design showed that this enrichment resulted in
significant differences in mechanical strength.
Abstract: This study aimed to present the mechanical
performance evaluation of the dynamic hip screw (DHS) for
trochanteric fracture by means of finite element method. The
analyses were performed based on stainless steel and titanium
implant material definitions at various stages of bone healing and
including implant removal. The assessment of the mechanical
performance used two parameters, von Mises stress to evaluate the
strength of bone and implant and elastic strain to evaluate fracture
stability. The results show several critical aspects of dynamic hip
screw for trochanteric fracture stabilization. In the initial stage of
bone healing process, partial weight bearing should be applied to
avoid the implant failure. In the late stage of bone healing, stainless
steel implant should be removed.
Abstract: This paper describes the development of an
autonomous robot for painting the interior walls of buildings. The
robot consists of a painting arm with an end effector roller that scans
the walls vertically and a mobile platform to give horizontal feed to
paint the whole area of the wall. The painting arm has a planar twolink
mechanism with two joints. Joints are driven from a stepping
motor through a ball screw-nut mechanism. Four ultrasonic sensors
are attached to the mobile platform and used to maintain a certain
distance from the facing wall and to avoid collision with side walls.
When settled on adjusted distance from the wall, the controller starts
the painting process autonomously. Simplicity, relatively low weight
and short painting time were considered in our design. Different
modules constituting the robot have been separately tested then
integrated. Experiments have shown successfulness of the robot in its
intended tasks.
Abstract: Plastics occupy wide place in the applications of
automotive, electronics and house goods. Especially reinforced
plastics become popular because of their high strength besides their
advantages of low weight and easy manufacturability. In this study,
mechanical and morphological properties of polypropylene (PP) and
high density polyethylene (HDPE) matrix composites reinforced with
surface modified nano titan dioxide (TiO2) particles were
investigated. Surface modification was made by coating the nano
powders with maleic anhydride grafted styrene ethylene butylene
styrene (SEBS-g-MA) and silane, respectively. After surface
modification, PP/TiO2 and HDPE/TiO2 composites were obtained by
using twin screw extruder at titan dioxide loading of 1 wt.%, 3 wt.%
and 5 wt.%. Effects of surface modification were determined by
thermal and morphological analysis. SEBS-g-MA provided bridging
effect between TiO2 particles and polymer matrix while silane was
effective as a dispersant. Depending on that, homogenous structures
without agglomeration were obtained. Mechanical tests were
performed on the injection moldings of the composites for obtaining
the impact strength, tensile strength, stress at break, elongation and
elastic modulus. Reinforced HDPE and PP moldings gave higher
tensile strength and elastic modulus due to the rigid structure of TiO2.
Slight increment was seen in stress at break. Elongation and impact
strength decreased due to the stiffness of the nano titan dioxide.
Abstract: For maintenance of a spine stability during the
postoperative period a transpedicular fixing of its elements is often
used. Usually the transpedicular systems are formed of rods which as
a result form a design of the frame type, fastening by screws to
vertebras. Such design should be rigid and perceive loadings
operating from the spine without essential deformations. From the
perfection point of view of known designs their stress
whole, and each of elements, in particular is of interest. In this study
the modeling of the transpedicular screw is performed and
estimation of its deformations taking into account interaction with a
vertebra body having variable structure is made.
Abstract: This current research focused on development of degradable starch based packaging film with enhanced mechanical properties. A series of low density polyethylene (LDPE)/tapioca starch compounds with various tapioca starch contents were prepared by twin screw extrusion with the addition of maleic anhydride grafted polyethylene as compatibilizer. Palm cooking oil was used as processing aid to ease the blown film process, thus, degradable film can be processed via conventional blown film machine. Studies on their characteristics, mechanical properties and biodegradation were carried out by Fourier Transform Infrared (FTIR) spectroscopy and optical properties, tensile test and exposure to fungi environment respectively. The presence of high starch contents had an adverse effect on the tensile properties of LDPE/tapioca starch blends. However, the addition of compatibilizer to the blends improved the interfacial adhesion between the two materials, hence, improved the tensile properties of the films. High content of starch amount also was found to increase the rate of biodegradability of LDPE/tapioca starch films. It can be proved by exposure of the film to fungi environment. A growth of microbes colony can be seen on the surface of LDPE/tapioca starch film indicates that the granular starch present on the surface of the polymer film is attacked by microorganisms, until most of it is assimilated as a carbon source.
Abstract: This paper proposes a robot able to climb Columns.
This robot is not dependent on the diameter and material of the
columns. Some climbing robots have been designed up to now but
Koala robot was designed and fabricated for climbing columns
exclusively. Simple kinematics of climbing in the nature inspired us
to design this robot. We used two linear mechanisms to grip the
column. The gripper consists of a DC motor and a power screw
mechanism with a linear bushing as a guide. This mechanism
provides enough force to grip the column. In addition we needed an
actuator for climbing the column; hence, two pneumatic jacks were
used. All the mechanical parts were designed according to the
exerted forces and operational condition. The prototype can be
simply installed and controlled on the column by an inexperienced
operator. This robot is intended for inspection and surveillance of
pipes in oil industries and power poles in electric industries.
Abstract: In this study, effects of premixed and equivalence
ratios on CO and HC emissions of a dual fuel HCCI engine are
investigated. Tests were conducted on a single-cylinder engine with
compression ratio of 17.5. Premixed gasoline is provided by a
carburetor connected to intake manifold and equipped with a screw
to adjust premixed air-fuel ratio, and diesel fuel is injected directly
into the cylinder through an injector at pressure of 250 bars. A heater
placed at inlet manifold is used to control the intake charge
temperature. Optimal intake charge temperature results in better
HCCI combustion due to formation of a homogeneous mixture,
therefore, all tests were carried out over the optimum intake
temperature of 110-115 ºC. Timing of diesel fuel injection has a great
effect on stratification of in-cylinder charge and plays an important
role in HCCI combustion phasing. Experiments indicated 35 BTDC
as the optimum injection timing. Varying the coolant temperature in
a range of 40 to 70 ºC, better HCCI combustion was achieved at 50
ºC. Therefore, coolant temperature was maintained 50 ºC during all
tests. Simultaneous investigation of effective parameters on HCCI
combustion was conducted to determine optimum parameters
resulting in fast transition to HCCI combustion. One of the
advantages of the method studied in this study is feasibility of easy
and fast transition of typical diesel engine to a dual fuel HCCI
engine. Results show that increasing premixed ratio, while keeping
EGR rate constant, increases unburned hydrocarbon (UHC)
emissions due to quenching phenomena and trapping of premixed
fuel in crevices, but CO emission decreases due to increase in CO to
CO2 reactions.
Abstract: In order to improve control performance and eliminate steady, a coupling compensation for 6-DOF parallel robot is presented. Taking dynamic load Tank Simulator as the research object, this paper analyzes the coupling of 6-DOC parallel robot considering the degree of freedom of the 6-DOF parallel manipulator. The coupling angle and coupling velocity are derived based on inverse kinematics model. It uses the mechanism-model combined method which takes practical moving track that considering the performance of motion controller and motor as its input to make the study. Experimental results show that the coupling compensation improves motion stability as well as accuracy. Besides, it decreases the dither amplitude of dynamic load Tank Simulator.
Abstract: In present study, two kinds of thermal power plant ashes; one the fly ash and the other waste ash are mixed with adhesive tragacanth and cement to produce new composite materials. 48 new samples are produced by varying the percentages of the fly ash, waste ash, cement and tragacanth. The new samples are subjected to some tests to find out their properties such as thermal conductivity, compressive strength, tensile strength and sucking capability of water. It is found that; the thermal conductivity decreases with increasing amount of tragacanth in the mixture. The compressive, tensile strength increases when the rate of tragacanth is up to 1%, whilst as the amount of tragacanth increases up to 1.5%, the compressive, tensile strength decreases slightly. The rate of water absorption of samples was more than 30%. From this result, it is concluded that these materials can not be used as external plaster or internal plaster material that faces to water. They can be used in internal plaster unless touching water and they can be used as cover plaster under roof and riprap material in sandwich panels. It is also found that, these materials can be cut with saw, drilled with screw and painted with any kind of paint.
Abstract: In order to make environmental test centrifuge balance
automatically and accurately, reduce unbalance centrifugal force,
balance adjusting system of centrifuge is designed. The new balance
adjusting system comprises motor-reducer, timing belt, screw pair,
slider-guideway and four rocker force sensors. According to
information obtained by the four rocker force sensors, unbalanced
value at both ends of the big arm is computed and heavy block is
moved to achieve balance adjusting. In this paper, motor power and
torque to move the heavy block is calculated. In full load running
progress of centrifuge, the stress-strain of screw pair composed by
adjusting nut and big arm are analyzed. A successful application of the
balance adjusting system is also put forwarded. The results show that
the balance adjusting system can satisfy balance require of
environmental test centrifuge.
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: This paper investigates the aerodynamic characters of a model ducted fan system, analyses the basic principle of the effect of thrust promotion and torque reduction, discovers the relationship between the revolutions per minute(RPM) of the fan and the characters of thrust, as well as system torque. Firstly a model ducted fan has been designed and manufactured according to the specific structure of flow field, then CFD simulation has been carried out to analyze such aerodynamics, finally bench tests have been used to validate the simulation results and system configuration.
Abstract: This paper proposed a stiffness analysis method for a
3-PRS mechanism for welding thick aluminum plate using FSW
technology. In the molding process, elastic deformation of lead-screws
and links are taken into account. This method is based on the virtual
work principle. Through a survey of the commonly used stiffness
performance indices, the minimum and maximum eigenvalues of the
stiffness matrix are used to evaluate the stiffness of the 3-PRS
mechanism. Furthermore, A FEA model has been constructed to verify
the method. Finally, we redefined the workspace using the stiffness
analysis method.
Abstract: Flour from Mucuna beans (Mucuna pruriens) were
used in producing texturized meat analogue using a single screw
extruder to monitor modifications on the proximate composition and
the functional properties at high moisture level. Response surface
methodology based on Box Behnken design at three levels of barrel
temperature (110, 120, 130°C), screw speed (100,120,140rpm) and
feed moisture (44, 47, 50%) were used in 17 runs. Regression models
describing the effect of variables on the product responses were
obtained. Descriptive profile analyses and consumer acceptability
test were carried out on optimized flavoured extruded meat analogue.
Responses were mostly affected by barrel temperature and moisture
level and to a lesser extent by screw speed. Optimization results
based on desirability concept indicated that a barrel temperature of
120.15°C, feed moisture of 47% and screw speed of 119.19 rpm
would produce meat analogue of preferable proximate composition,
functional and sensory properties which reveals consumers` likeness
for the product.