Dynamic
stability of vehicles is a major concern to vehicle manufacturers, as this
determines how safe a vehicle will be on the road, to passengers and other road
users. The location of centre of gravity (CG) on a vehicle determines its
stability. The objective of this work is to evaluate the dynamic stability of a
modeled cargo tricycle. The mass Properties capability of the SolidWorks
software was used to determine the CG location on the tricycle. Result shows
that the model will response to side load with a yaw motion and it’s an
oversteer vehicle. Therefore it is unstable at high speed above its critical
speed. The rollover threshold (Fc) for the tricycle model is 0.32g.
Monday, 29 June 2015
Mechanical Stress Analysis of Tree Branches
Various
models have been developed to calculate stresses due to weight along tree
branches. Most studies have assumed a uniform modulus of elasticity and others
have assumed that branches are tapered cantilever beams orientated horizontally
or at an angle. Astress model was evaluated in which branches are curved and
that the modulus of elasticity may vary along the branch. For this model, the
cross-sectional areasof branches were divided into concentric rings in which
the modulus of elasticity may vary. Next, areas of rings were transformed
according to their modulus of elasticity. Branches with curved shapes were also
considered and best fit lines for branch diameters were developed. A generated
diameter equation was used in the stress calculations to provide realistic
results. From these equations, a Graphical User Interface (GUI) in Matlab, was
developed to calculate stress within tree branches. Moreover, a Finite Element
Model (FEM) was created in Abaqus to compare with the models.
Website: http://www.arjonline.org/engineering/american-research-journal-of-mechanical-and-automation-engineering/
Website: http://www.arjonline.org/engineering/american-research-journal-of-mechanical-and-automation-engineering/
Hydro-Structure Analysis of Composite Marine Propeller under Pressure Hydrodynamic Loading
Because
of the loading on the propeller blade, it goes under significant deformation
that may affect the hydrodynamic performance of the propeller. Thus, the blade
deformation of a propeller due to fluid pressure should be analyzed,
considering hydro-elastic analysis. The propeller was made of anisotropic
composite materials, and the geometry of the propeller is for one skew angle.
First, the hydrodynamic pressure loading is obtained by FVM and then the
deformation of the blade due to this pressure was calculated. Next, the
pressure load for deformed propeller is achieved; it is again repeated to
obtain the new deformed propeller. This procedure is repeated to converge the
thrust, torque and efficiency. We present all results of the pressure
distribution, hydrodynamic characteristics, stress and deformation of the
propeller.
Website: http://www.arjonline.org/engineering/american-research-journal-of-mechanical-and-automation-engineering/
Website: http://www.arjonline.org/engineering/american-research-journal-of-mechanical-and-automation-engineering/
Mechanical Model of Hydrogen Bonds in Protein Molecules
The
unique properties of protein molecules have motivated researchers exploit them
in the design and fabrication of bio-mimetic nano devices to perform a special
task. Function of protein molecules is in turn dependent on their 3D structure
and their ability to modify their shape for a specific task. To study and
manipulate protein molecules we need to have knowledge of mechanical properties
of these molecules. In this paper a multiscale model to predict stiffness of
helical protein molecules has been developed. Hydrogen bonds as major
contributing factor to proteins flexibility, are modeled as elastic springs
based on their empirical potential energy. Such mechanical representation of
hydrogen bonds enables us to obtain the stiffness ellipsoid of hydrogen bonds
which leads to an understanding of the directional stiffness of protein
molecules. The model has also been applied to three different protein molecules
whose stiffness were reported in the literature. The comparison shows an
agreement between the stiffness computed by the proposed model and that
obtained through experiments and/or Molecular Dynamics (MD) simulations.
Website: http://www.arjonline.org/engineering/american-research-journal-of-mechanical-and-automation-engineering/
Website: http://www.arjonline.org/engineering/american-research-journal-of-mechanical-and-automation-engineering/
Modeling of Thermal Mass in a Small Commercial Building and Potential Improvement by Applying TABS
With
a resistor-capacitor model built in Matlab/Simulink, the role of
envelope/interior thermal mass (eTM/iTM) in a small commercial building is
investigated systematically. It concludes that light-weight concrete is a
little worse than normal-weight concrete but much better than wood as eTM or
iTM for controlling operative temperature variation in the building. In order
to combine the advantages of radiant cooling/heating with the heat storage of
massive building structure, an attractive technique called TABS (thermally
activated building systems) is applied to the building to investigate the
potential improvement. Simulations demonstrate that TABS can keep the operative
temperature level around the comfort zone with small variations. As TABS is a
low-temperature heating and high-temperature cooling technique, it suggests
that natural energy gradient driven low-power equipment, such as cooling tower
and rooftop solar thermal panels, can be used to achieve free cooling/heating
combining photovoltaics
Website: http://www.arjonline.org/engineering/american-research-journal-of-mechanical-and-automation-engineering/
Website: http://www.arjonline.org/engineering/american-research-journal-of-mechanical-and-automation-engineering/
The Role of Thermal Mass in a U.S. Prototypical Residential House
Thermal
mass is important for controlling temperature in buildings. This paper
systematically investigates the roles of exterior and interior thermal mass
(eTM/iTM) in a U.S. prototypical residential house. A resistor-capacitor (RC)
model of the house is built in Matlab/Simulink. Simulation results show that,
with normal amount of iTM in a wood-envelope house, changing the wood thickness
in a reasonable range can keep the operative temperature variation in 2.1-3.4
°C; correspondingly, in a concrete-envelope house, the variation is in 0.9-1.9
°C. With constant envelope total thermal resistance, adequate iTM and
sufficient heat EXCHANGE RATE between iTM and indoor air are both necessary to
maintain the operative temperature variation in a small range. It shows that
concrete as iTM has a better control on operative temperature than wood, and
thus from the point of view of heat storage, concrete is better than wood as
thermal mass due to its larger heat capacity.
Website: http://www.arjonline.org/engineering/american-research-journal-of-mechanical-and-automation-engineering/
Website: http://www.arjonline.org/engineering/american-research-journal-of-mechanical-and-automation-engineering/
Production of Biogas by Anaerobic Digestion of Food Waste and Process Simulation
The
produced methane then can be directly used for rural cooking; or after certain
conditioning, can be used in onsite power generation, heating homes or as
vehicular fuel. Besides, food waste is increasingly becoming a major problem in
every society imposing serious economic and environmental concerns. For this
reason, many contemporary researches are emphasizing in finding sustainable
solutions to recycle and produce energy from such waste. In this context, this
paper aims to study and optimize the production of biogas from food waste
(rice). For the experiment, an existing wet digestion biogas plant installed in
Islamic University of Technology was used. The food waste (rice) for the
research was collected from the cafeteria of Islamic University of Technology.
Furthermore, a process simulation was performed by PROII software to estimate
the methane production rate. Eventually, the simulated and experimental results
were compared. The duration of the study period was 120 days. The experimental
results showed that an average specific gas production of 14.4 kg-mol/hr can be
obtained for 0.05 kg-mol/hr of starch loading rate. In case of the simulated
results, the gas production was found to be 19.82 kg-mol/hr for the same
loading rate of starch. The percentage of methane and CO2 obtained in the
biogas plant was 69% and 29% respectively.
Website: http://www.arjonline.org/engineering/american-research-journal-of-mechanical-and-automation-engineering/
Website: http://www.arjonline.org/engineering/american-research-journal-of-mechanical-and-automation-engineering/
Modelling and Design of an Auto Street Light Generation Speed Breaker Mechanism
The
mechanism converts the kinetic energy of vehicles at speed bump into electric
energy. A preliminary modelling of the speed breaker system was developed. The
component members were designed and modelled on SolidWorks software based on
the properties of the selected materials. A static and fatigue analysis of the
spring using SolidWorks reveals a yield stress of 172.3 Mpa. The computational
fluid dynamics of the air reveals an average total pressure and velocity of
29.74 bar and 1.018 m/srespectively.The conceptual design was carried out and
resulted to the selection of materials needed for each component of the design.
A prototype of the speed breaker mechanism was constructed and tested. The
mechanism generated 6V D.C which validates the principle. The light sensor
automatically opens the valve to on the light when it is dark and closes it to
off the light at dawn.
Website: http://www.arjonline.org/engineering/american-research-journal-of-mechanical-and-automation-engineering/
Website: http://www.arjonline.org/engineering/american-research-journal-of-mechanical-and-automation-engineering/
Optimization of Process Parameters of Manual Arc Welding of Mild Steel Using Taguchi Method
The
tensile test was carried out on extracted welded and unwelded specimens using
universal testing machine (UTM). Microstructures of the welded specimens were
carried out and analyzed. Statistical analysis (ANOVA) and signal to noise
ratio were used to study the significant effect of input parameters on ultimate
tensile strength and optimized conditions for the process performance
respectively. The results showed that experiment number 7 has the highest
ultimate tensile strength (UTS) of 487MPa and S/N ratio of 53.74 dB. The S/N
ratio of higher value indicates better characteristic of optimum MMAW process
performance. The study shows that the optimum condition is A3B1C3D2 at welding
current 100A, electrode angle of 700, root gap of 3.3 mm and a welding speed of
3.6 mm/s .
Website: http://www.arjonline.org/engineering/american-research-journal-of-mechanical-and-automation-engineering/
Website: http://www.arjonline.org/engineering/american-research-journal-of-mechanical-and-automation-engineering/
Experimental and Numerical Analysis of Fatigue during the Cyclic Loading
The
experimental determination of Wöhler fatigue curve and knowledge in relation to
the material data for the tested construction material is based on the
experimental results of the testing machine SCHANCK used for determination of
the mechanical fatigue. In the given work, there is the introduction of the
research in the field of the fatigue based on cyclic loading by bending and
moreover, the given research is combined with the modern computational methods
of the mechanics of continuum. In relation to the numerical analysis, the given
thesis is focused on the creation of the computational model according to the
geometry of the tested sample in an experimental way and this computational
model can help us to obtain the most reliable results for the simulation of the
loading with utilisation of the computational program system on the basis of
the finite element method. The total numerical time was also taken into account
because of the achievement of the fast response to the change of the material,
geometrical and other parameters during the creation of the computational
model. The obtained results based on the experimental analysis as well as
numerical analysis were mutually compared. The numerical analysis and
experimental measurement can be also applied for the other types of materials.
Website: http://www.arjonline.org/engineering/american-research-journal-of-mechanical-and-automation-engineering/
Website: http://www.arjonline.org/engineering/american-research-journal-of-mechanical-and-automation-engineering/
Home Security System Using Reconfigurable Robot
Mobile
robots are now widely used in various security and surveillance applications.
The contribution describes a design of the robot with the function of the
security system in the home. The robot is movable on wheels with various
sensors, which sense the movement in the home. Based on detected movement will
start tracking the object and shooting the camera. Picture and sound are
transmitted to the mobile phone via 3G video call.
Website: http://www.arjonline.org/engineering/american-research-journal-of-mechanical-and-automation-engineering/
Website: http://www.arjonline.org/engineering/american-research-journal-of-mechanical-and-automation-engineering/
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