Asish Bandyopadhyay

Desirability Function Approach for Solving Multi-Objective Optimization Problem in Submerged Arc Welding

Like any other welding technique, Submerged Arc Welding (SAW) is also a multi-objective, multi-variable metal processing technology. In general, the acceptability of a weldment depends on various parameters in relation to bead geometry, bead quality, microstructure and mechanical-metallurgical characteristics of the weld, that can fulfill the required goal. The acceptable limits of these parameters are also influenced by the area of application as well as functional requirements of the prepared weld. Therefore, there exists a need to search for an optimal process condition that may achieve the desired purpose. In the present work, it is aimed to search for an optimal solution for the process parameters that would result in maximum depth of penetration, minimum height of reinforcement, minimum bead width, minimum dilution, minimum area of reinforcement and minimum area of penetration, within experimental domain. Data, collected from previous research for four factor-five level central composite design, have been utilized to determine individual desirability of the responses, which have been used further to calculate composite desirability associated with overall features of bead geometry and bead volume of the desired weldment. Desirability function optimization approach, followed by Response Surface Methodology (RSM), has been incorporated to evaluate the optimum parameter setting that would meet * Communicating Author the overall desirability of the weldment. Comparison of optimal parametric combination as determined by the previous researchers to that obtained by using desirability function approach and RSM has also been made. Good agreement has been found. This proves the application feasibility of desirability function approach coupled with RSM for solving multi-objective optimization problems in SA welding.

Investigation of forced convective heat transfer enhancement in the presence of an electric field – a finite element analysis

The effect of electro‐convection in a cylindrical flow annulus on heat transfer enhancement has been investigated numerically. Weakly ionized air is considered to be the working fluid throughout this work. The effect of exit boundary condition, considered to be the main hindrance for the numerical solution, has been discussed in detail. The present work shows interesting flow field characteristics, which are in excellent agreement with some other established experiments. The heat transfer enhancement, as reported in this work, appears to be small in view of the low magnitude of the applied voltage but it clearly and surely delineates the trend, i.e. with increase in the strength of the electric field, heat transfer enhances.

INVESTIGATION ON SURFACE ROUGHNESS IN CYLINDRICAL GRINDING

Cylindrical grinding is a complex machining process. And surface roughness is often a key factor in any machining process while considering the machine tool or machining performance. Further, surface roughness is one of the measures of the technological quality of the product and is a factor that greatly influences cost and quality. The present work is related to some aspects of surface finish in the context of traverse‐cut cylindrical grinding. The parameters considered have been: infeed, longitudinal feed and work speed. Taguchi quality design is used to design the experiments and to identify the significantly import parameter(s) affecting the surface roughness. By utilization of Response Surface Methodology (RSM), second order differential equation has been developed and attempts have also been made for optimization of the process in the context of surface roughness by using C‐ programming.

Roughness modelling and optimisation in EDM using response surface method for different work piece materials

Influence of machining parameters, viz., pulse current, pulse on time and pulse off time on the quality of surface produced in electrical discharge machining (EDM) is investigated. Experiments are conducted for three different work piece materials to see the effect of work piece material variation in this respect. Five roughness parameters, viz., centreline average roughness, root mean square roughness; skewness, kurtosis and mean line peak spacing have been considered. The second order mathematical models have been developed for each of these five-roughness parameters predictions using response surface methodology. The roughness models, as well as the significance of the machining parameters, have been validated with analysis of variance. The response surface models are found to be specific to work piece materials. An attempt has also been made to obtain optimum machining conditions using response optimisation technique.

An Investigation on Temperature Distribution and Cooling Rate of ERW Pipes during TIG Welding

Abstract The present investigation deals with the determination of temperature profile and subsequent rates of cooling at certain points on the external surface along axis of an ERW pipe, during TIG welding. Two samples of different diameters of pipes of ASTM A 106 Gr. B, seamless type are selected for experimentation. The temperatures on the external surface at different locations on each of these seamless pipes (of different diameters) during welding have been measured with the help of digital pyrometers. The temperature variation along the axis of pipe from the weld arc has been presented. Thereafter, through separate analytical methods the temperature distribution across the external surface of the pipe for a given point heat source is theoretically calculated, and the results are compared with the previously found experimental values of temperatures. They are found to be well in agreement. Further, the rates of cooling of a pre-selected point on the pipe surface are experimentally and analytically determined under varying welding conditions and are compared likewise and are found to be in good agreement too.

A study on quality of weld in flux cored arc welding process

Flux cored arc welding (FCAW) is a semi–automatic or fully automatic welding method that is widely used for welding large and thick sections, especially in the flat position. The welding can be performed with shielding gas (FCAW–G) or without shielding gas (FCAW–S). A tubular filler wire containing mixture of mineral flux and powder in the core of the tube is supplied on reels and fed through the welding gun in metal inert gas (MIG) welding. The process is popularly used in construction and fabrication of carbon steel, low alloy steel weldment in power plant equipment. Hence in this paper effects of the welding parameters on the quality of weldment have been discussed based on the experimental data obtained. The welding was performed on metal plates of boiler quality of steel using a semiautomatic gas metal arc welding (GMAW) machine. To predict the weld quality, experiments were conducted based on three–factor five levels Taguchi orthogonal array design matrix. Parametric optimisation has been done based on radiographic test, visual inspection and tensile test results.

Multi-objective optimisation of abrasive water jet machining responses by simulated annealing and particle swarm

Optimum control parameter settings in complex and stochastic type processes are one of the most challenging problems to the process engineers. As such, effective model development and determination of optimal operating conditions of abrasive water jet machining process (AWJM) are reasonably difficult. In this article new modifications are proposed on two single-objective optimisation techniques, simulated annealing and particle swarm optimisation and applied to optimise two response parameters in AWJM – material removal rate (MRR) and depth of cut (DOC) simultaneously. For the optimisation purpose statistical models are developed from experimental data obtained from AWJ machining of amorphous material – borosilicate glass. Optimum results are validated and it is suggested to employ particle swarm-based proposed multi-objective optimisation technique in present case for newly modelled system due to its fast convergence and low memory space requirement.

Solution of Correlated Multi-Response Optimization Problem: Case Study in Submerged Arc Welding

This paper highlights an integrated approach to solve the correlated multi-response optimization problem through a case study in submerged arc welding (SAW). The proposed approach has been presented to overcome different limitations and drawbacks of existing optimization techniques available in literature. Traditional Taguchi optimization technique is based under the assumption that quality responses are independent to each other; however, this assumption may not always be valid. A common trend in the solution of a multi-objective optimization problem is to convert these multi-objectives into an equivalent single objective function. While deriving this equivalent objective function, different weightage are assigned to different responses according to their relative priority. In this regard, it seems that no specific guideline is available for assigning individual response weighs. To avoid this, Principal Component Analysis (PCA) has been adopted to eliminate correlation among individual desirability values and to calculate uncorrelated quality indices that have been aggregated to calculate overall grey relational grade. This study combines PCA, Desirability Function (DF) approach, and grey relation theory to the entropy measurement technique. Finally, the Taguchi method has been used to derive optimal process environment capable of producing desired weld quality related to bead geometry.

Investigation of Titanium Silicon Nitride: A Review

Nano-tribological studies are required to develop in-depth understanding on interfacial phenomena of different materials that are used in different industrial (e.g. aerospace industry, coatings, tool hardening electronics devices etc.) applications. In a recent year, tribological studies on transition metals increase because of their promising mechanical properties, hardness, oxidation resistant and wear resistant characteristics. Titanium silicon nitride is considered to be one of the most prominent materials among all the transition metals. Silicon provides excellent resistance to oxidation and titanium guarantees hard coatings. So, combination of two can be developed a useful coating material which can provide wear resistance even at elevated temperature.

An Investigation on Slab Milling Operation to Find Out Optimum Cutting Parameters

Milling is a widely used machining operation. For generating a flat wide surface, slab milling is usually employed in industry. In this experimental work, slab milling operation has been performed on low alloy steel to obtain appropriate cutting parameters in order to get low surface roughness, low vibration and high material removal rate. Taguchi method and composite desirability function of response surface methodology have been used to get required cutting parameters. It has been observed from Taguchi’s methodology that surface roughness is affected mostly by variation of cutting velocity or speed; in case of material removal rate, effect of feed is quite high, and speed also has sufficient effect on it.