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The Effect of Rare Earth Addition and Stirring
on the Mechanical Properties of a Cast A356 Alloy
--Bharat Bhushan, Balraj Singh, Deepak Suthar, Jyoti Menghani and Dimple V Shah
A356 Al alloy containing 7% Si and 0.3% Mg is widely used in automobile and aircraft industries due to excellent castability, good corrosion resistance and good pressure tightness. The present investigation was undertaken to explore the possibilities of rare earth metal additions primarily as modifiers of eutectic silicon and secondarily beneficial alloying element. In the present study, the effect of rare earth addition and stirring on the mechanical properties of a cast A356 alloy was studied. Alloy was casted by addition of 0%, 0.5 wt%, 1.5 wt% rare earth along with 0, 400 and 600 rpm of stirring speed. Microstructural characterization of the casted A356 alloy was carried out by means of Optical Microscopy and its phases were detected by XRD. Mechanical characterization was based on tensile and hardness tests. Inclusion of rare earth along with stirring gives grain refinement and increases the strength of the as-cast alloy. Optimal rare earth addition was found to be 0.5% at 600 rpm of stirring speed. Addition of rare earth causes formation of intermetallic compound as observed in XRD and stirring results in size reduction of dendrites and desegregation of Si needles present in A356 alloy. © 2015 IUP. All Rights Reserved.
An Application to Detect Knock and Combustion Severity
of Diesel Engine Working with Biodiesel (COME)-
Additive Blends Using Cylinder Vibration Signature
--P Venkateswara Rao and B V Appa Rao
Knock is an undesirable combustion mode occurring in diesel engines due to longer delay period that decreases the engine performance and life. In diesel engine, knock is mainly due to the improper fuel burning or missing caused by the injection system problems. Engine miss causes rapid combustion with very high pressures generating a rumble or dull clattering sound with violent vibration called “knocking or detonation”. The method introduced in the present study using alternate fuel (biodiesel-triacetin additive) in the engine suggests a newly developed approach towards analyzing the cylinder vibration of diesel engine. This method is based on fundamental relationship between the engine vibrations pattern and relative characteristics of the combustion process in the cylinder. Vibrations generated by the engine during knock are measured by using DC-11 Fast Fourier Transform (FFT) analyzer with accelerometer. The FFT output at each load of the cylinder excitation frequencies is obtained and compared with the frequencies of diesel fuel as base line. Time waveforms on the cylinder head and derived heat release rate curves are used to analyze the modus operandi of how combustion generates the vibrations and finally to detect the engine knock. © 2015 IUP. All Rights Reserved.
Mesoscopic Modeling of Density-Internal Energy
Distribution Function for Convection Heat Transfer
--D Arumuga Perumal
This paper focuses on the mesoscopic methodology of density-internal energy lattice Boltzmann computation of two-dimensional natural convection in a square cavity filled with porous medium. It is realized that the impact of permeable media is acquainted by including porosity with the balance molecule thickness conveyance capacity and by adding energy term to the molecule thickness dispersion capacity. In the present paper, density-internal energy distribution function lattice Boltzmann model is utilized to recreate convection in permeable medium at the Representative Elementary Volume (REV) scale. The two-dimensional nine-speed model (D2Q9) with nine discrete speeds is utilized as a part of the work. The impact of Rayleigh number, Darcy number and porosity are mulled over. The boundary conditions used are stable and also correct. It is concluded that the present study on finite porous enclosure produces results that are in excellent conformity with earlier conventional numerical observations. © 2015 IUP. All Rights Reserved.
Process Control Through Measurement of Cp and Cpk
of a Production Process
--D R Prajapati
It is a fact that no two products are exactly alike because of slight differences in materials, workers, machines, tools and other factors. These are called common or random causes of variation. Common causes of variation are based on random causes that we cannot identify. The combination of Cp and Cpk is used extensively because it shows both the potential process capabilities. The Process Capability Ratio (PCR) and Process Capability Index (Cpk) for a kick starter gear drive (depth of pitch problem) were computed after stabilizing the manufacturing process. Data were taken from the manufacturing process and the and R control charts were plotted to find whether the processes are within statistical control or out of statistical control. The process capability analysis was done to find out the effectiveness of the processes. It was found that 0.465% of kick starter gear due to depth of pitch was beyond the control limits, which is really a major concern for the industry. © 2015 IUP. All Rights Reserved.
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