Mechanical Engineering

Wave propagation method (WPM) is utilized, for the first time, to study the resonance response of Atomic Force Microscopy (AFM). The damping coefficient with in the interaction of tip-sample, which is assumed as a linear visco-elastic force, is considered in this paper as it has been neglected in the WPM studies of beam in previous investigations. Experiment and analytical results are provided in order to show the reliability and correctness of WPM method. The results are in good agreements with the experiments and show that the WPM is more accrue than analytical method.

The use of tractors for agricultural works showed an important role to mechanized agricultural sector. A repairable mechanical system (as agricultural tractor) is subject to deterioration or repeated failure. In this study, the regression model was used to predict the failure rate of MF399 tractor. The machine failure pattern was carefully studied and key factors affecting the failure rate were identified in five regions of Khouzestan province. Results showed that different annual use hours (AUH) and maintenance policies affected failure rate. According to the data, the MF399 tractors included in 300-1000 AUH were commonly in a randomized breakdown period during their useful life but these tractors tend to enter the wear out period in the 1200-2000 AUH.

In an ever increasingly competitive environment, product design forms the foundation for enduring sales responsiveness and enhanced customer satisfaction. Superior product performance, quality and reduced cost of ownership are the results of effective, efficient engineering and design. The impact of product design on total cost of ownership and the profitability of a manufacturing company are significant. This paper addresses design for total cost of ownership approach for allocation of redundancy that can minimize the total cost of the product during the product life time. A genetic algorithm based heuristic is developed to provide an optimal or a near optimal solution. This DTCO approach permits engineers to study product designs with respect to cost, reliability and performance during the conceptual design phase and enables the integrated method to identify design changes that improve performance and reduce total cost of ownership.

This paper reveals the mechanical and metallurgical properties of the dissimilar joints of AA2024 aluminium alloy and commercial grade copper alloy fabricated by diffusion bonding process. Three diffusion bonds with varying diffusion layer thickness were fabricated and study the effect of diffusion layer thickness on mechanical and metallurgical properties. Mechanical properties such as lap shear strength, bonding strength and hardness are evaluated, Metallurgical characteristics such as diffusion layers thickness, phases in diffusion layer, elemental composition of diffusion layers were analysed. From this investigation, it is found that the diffusion bond with a medium diffusion layer thickness (in between very minimum to very maximum) exhibits superior mechanical properties.

A numerical study is presented on the effects of chemical reaction and magnetic field on the unsteady free convection flow, heat and mass transfer characteristics in a viscous, incompressible and electrically conducting fluid past an exponentially accelerated vertical plate embedded in a porous medium by taking into account the heat due to viscous dissipation. The problem is governed by coupled non-linear partial differential equations. The dimensionless equations of the problem have been solved numerically by the implicit finite difference method of Crank – Nicolson’s type. The effects of governing parameters on the flow variables are discussed quantitatively with the aid of graphs for the flow field, temperature field, concentration field, skin-friction, Nusselt number and Sherwood number. It is found that under the influence of chemical reaction, the flow velocity as well as concentration distributions reduce, while the velocity reduces as porous medium increases. Viscous dissipation parameter leads to increase the temperature.

Vortex tube is a device that separates pressurized inlet gas into hot and cold streams. Its main applications are in spot cooling. Hence cold temperature of outlet gas, as a response variable, is of much concern for experimentation. There are various input controllable parameters, the values (levels) of which may affect the cold temperature of outlet gas. Some studies were carried out on vortex tube hitherto, considering different input controllable parameters. The present work analyses the effect of five input controllable parameters viz., inlet gas (air) Pressure, Length of the vortex (hot)tube, Diameter of the vortex(hot) tube, Diameter of the orifice / diaphragm, and Diameter of the nozzle on the response variable- Temperature of cold-outlet stream of air. Response Surface Methodology (RSM) approach is used to optimize the response. L-27 Orthogonal Array (OA) is used for experimentation. Response is of “Smaller the Better” type. Regression equation is obtained. All the parameters considered but the Length of the vortex tube, are found to be significant from the Analysis of Variance ( ANOVA ) table. Optimum levels for factors are predicted, confirmatory test is run and the experimental results are validated.

Machining is the most important of the manufacturing processes which involves the process of removing material from a workpiece in the form of chips. Machining is necessary where tight tolerances on dimensions and finishes are required. Being such an important process in manufacturing industry, a machining process is considered for investigation in the present work. This paper presents the experimental investigations on the effects of cutting variables like Spindle speed, Feed and Depth of cut on the Material removal rate and tool wear. The experiments were conducted on AISI SI steel grade on a CNC turning machine using ceramic insert. The experiments were conducted as per the design of experiments. Initial trial experiments were conducted to fix the ranges for the control parameters. After conducting the experiments the MRR and Tool wear were measured and recorded. The effects were studied after plotting the graphs between the Input process parameters versus the responses using Design expert software. The results obtained in this study can by further used for optimizing the process parameters there by the optimized results help the operator to enhance the quality as well as machining rate

This paper presents an experimental investigation on the influence of cutting parameters of wire cut Electrical Discharge Machining (Wire-EDM) during the machining of Inconel825.Demand for better surface finish has been increasing recently for super alloys. The low rigidity and high material removal rate of Inconel alloys offers a challenging task in obtaining a better surface finish. The analysis of surface characteristics like surface roughness of Inconel-825 is carried out and an excellent machined finish can be obtained by setting the machining parameters at optimum level. Experimentation has been done by using Taguchi’s L18 (21x37) orthogonal array under different conditions of parameters. The response of surface roughness is considered for improving the machining efficiency. Optimal combinations of parameters were obtained by this method. The confirmation experiment shows, the significant improvement in surface finish (1.36µm) was obtained. Multiple linear regression model have been developed relating the process parameters and machining performance indicates the suitability of the proposed model in predicting surface roughness. The regression analysis are used to predict the error between actual and regression values of surface roughness in Wire EDM process. Experimental results demonstrate that the machining model is suitable and the Taguchi’s method satisfies the practical requirements.

In this paper Taguchi method is applied for determining the effect of process parameters on vortex tube made of Delrin material. An Experimental work is carried out to analyze the performance of vortex tube with five controllable input parameters namely diameter of the orifices, diameter of the nozzles, length of hot tube, tube diameter and inlet pressure. Cold temperature is considered as output parameter. The various parameters like S/N analysis, ANOVA and Optimal Cold Temperature were carried out in order to determine the effects of process parameters and optimal factor settings.

This paper investigates the development of Al6061/Si3N4 metal matrix composites using stir casting technique and optimize the process parameters in turning based on Genetic Algorithm. In this metal matrix composites Al 6061 alloy reinforced with 3% and 5% weight by volume of Si3N4 particles of mean diameter 75µm was used. Experiments were performed in the CNC lathe by using CNMG inserts at various cutting conditions and parameters such as cutting speed, feed and depth of cut and surface roughness was found at different levels. The optimization of machining parameters was done by using Genetic Algorithm.