|
Densification Behavior Modeling for Al-Pb
Alloys Produced by Mechanical Alloying Through Attrition Milling
-- Ch.V S H S R Sastry and G Ranga Janardhana
The recent research of the alternate sliding bearing materials unequivocally
points to the beneficial role of Lead (Pb) in Aluminum (Al). But, these alloys offer a manufacturing challenge, due to wide
immiscibility gap. For such applications, apart from homogeneous microstructure, porosity control is also equally
important, as it influences the tribological performance through spreading of
Lead in Aluminum matrix. These objectives can be achieved by mechanical alloying through attrition milling. In order to control the shape of
the final Powder Metallurgical (P/M) parts, appropriate models are necessary for densification of composite
powders to simulate cold compaction responses. In the present work, the authors studied the effect of alloy
composition and the ball to charge ratio on the densification behavior of attrition milled Al-Pb alloys, with a view
to develop nonlinear regression models that can best describe the densification behavior of attrition milled
Al-Pb alloys, from compressibility test data. Based on their validation, the study concludes that
Richard's model effectively predicts densification behavior of attrition milled Al-Pb alloys. Such modeling will be of
great significance in simulating the cold compaction response, especially in case of alloys where no historical
data exists regarding the effect of processing conditions on densification behavior. © 2009 IUP. All Rights Reserved.
Dynamic Balancing of a CNC Machine Spindle Using Vibration Signature: A Case Study of
Turning Center on Condition Monitoring
-- V Hariharan and P S S Srinivasan
Reliability and accuracy of rotating machinery is very essential for obtaining accurate components.
The vibration level of the spindle and balancing of
the rotating member in rotating machinery is very
important to achieve this. This study involves vibration analysis and dynamic balancing in reducing the spindle
vibrations to a minimum possible level. As the rotational speed of
the machine increases, centrifugal forces due to unbalanced forces increase
dramatically, which in turn increases the vibration leading to equipment
reliability and product quality problems. This paper illustrates the balancing of CNC turning center with the help
of vibration signatures. Three levels of balancing have been considered.
The signal is acquired with the help of powerful dual channel vibration
analyzer, ADASH V4300 along with the accelerometer and taco
sensor. Graphs are presented before and after balancing. © 2009 IUP. All Rights Reserved.
Enhancing Thermal Efficiency of Solar Pond
with Planar Reflector
-- S C Sharma and A Tiwari
Solar ponds have a horizontal surface, and
therefore, the solar radiation received per unit area is less
as compared to what is received on the surface normal to solar radiation. In addition to
this, once the solar pond is constructed it cannot supply increased demand of thermal energy, if need arises. These two limitations
of the solar pond can be overcome by the use of planar
reflectors. These reflectors reflect the solar
radiation, and hence, increase the radiation input to the solar pond. As a result, the pond not only
supplies more heat energy but also saves on land cost to provide the same amount of energy. The enhancement of the
average radiation gain in a solar pond using planar reflector has been studied and calculated for Indore city in
India. The results are then compared with the performance of the pond without reflector. It is found that the
use of reflector having area only 5% of the total area of the pond can increase the radiation gain by more
than 10%. This can further be enhanced by increasing the area of the reflector,
considering the economic feasibility. © 2009 IUP. All Rights Reserved.
Fabrication and Tensile Testing of Gfrp Joints
-- D Suneel, D Nageswara Rao and T V D B N Kartheek
Over centuries, so many fastening techniques have been developed and are in use. Each technique has its own pros
and cons. With the evolution of composite science and technology, many applications have come into picture. Out of them,
one is the joining of similar and dissimilar metals using Glass Fiber Reinforced Polymer (GFRP). The present paper
deals with joining and tensile testing of similar metals using GFRP and comparing the results with arc welded joints of
the same configuration. Finally, the FRP joint is also subjected to leak detection test. © 2009 IUP. All Rights Reserved.
Prediction of Optimal Stability States in
Inward-Turning Operation Using Genetic Algorithms
-- K Rama Kotaiah and J Srinivas
This paper proposes a neural network-based optimization scheme for predicting localized stable
cutting states in inward-turning operation. A set of cutting experiments are performed in inward orthogonal
turning operation. The cutting forces and critical chatter locations are predicted as a function of operating
variables including tool overhang length. A neural network model is employed to develop the generalized
relations. The optimum cutting parameters are predicted from the model with the help of binary-coded
Genetic Algorithms (GA). The results are illustrated with the data of four different work
materials. © 2009 IUP. All Rights Reserved.
Thermodynamic Study of Gas/Steam Combined Cycle Employing Inlet Air Cooling, Fuel
Heating and Closed Loop Cooling in Topping Cycle
-- J P Yadav and Onkar Singh
The temperature of air entering the compressor of a
gas turbine plant significantly affects the work
availability from the plant. In order to have lesser compressor work requirement the temperature of air entering
the compressor should be low. Gas turbine cycle efficiency can also be improved by reducing the heat addition
in the combustion chamber for the same turbine inlet temperature. In this
paper, a combined cycle arrangement employing compressor inlet
air cooling and fuel heating prior to injection in the combustion chamber
is considered for thermodynamic analysis. The variation in inlet air temperature at
the inlet of the compressor and fuel preheating using a part of steam generated in
Heat Recovery Steam Generator (HRSG) is
considered. Closed loop cooling technique is used for maintaining the gas turbine blade temperature within
metallurgical limits. Water bled after condenser and steam generated at three different
pressures and temperatures is used to meet the coolant and fuel heating requirements. The results obtained have been plotted suitably
for studying the influence of one parameter upon the
other at varying cycle pressure ratio and turbine
inlet temperatures. © 2009 IUP. All Rights Reserved.
|
