Mechanical Engineering

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.

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.

Failures of equipments and process costs money. The reasons for failure could be either a bad design, improper working conditions, failure of system components as they approaches the wear out stage or a combination of these factors. There is no way of completely eliminating failures. However, a better understanding of the causes and mechanisms of equipment failure can allow failure control measures to be developed and implemented. Unreliability is the costly part of the economic equation and adopting measures to improve reliability and availability of the system will ultimately result in economic gain. The present work attempts to provide an estimate of the net effect of modification that is required for a system by using the control chart procedure. The method involves plotting control charts for each of the components using the time to fail. The central line of the control chart corresponds to the Mean Time Between Failure (MTBF) and the control limits are placed at a distance of from the mean line and is based on t- distribution. The components that require an improvement with regard to failure rate is identified by analysing the control charts. The desired change in the component availabilities as well as the system availability can be obtained and an estimate of the net effect of modification is also arrived. The model can provide a measure of the performance of the components as well as that of the system. The quantification of the improvements required, if any, can be obtained using the model. A 11 step algorithm is also developed based on the model. It is hoped that the developed model and algorithm will prove to be a powerful tool in process reliability analysis.

In this research work, effect of outer jacket insulation on energy equivalent of bomb calorimeter has been analyzed. Energy equivalent shows the sum of the heat capacities of the components in the calorimeter, especially the bomb, the bucket and the water in the bucket. Energy equivalents are determined at regular intervals by experimenting with a sample of a standard material with a known heat of combustion. Emphasis is being placed on minimizing thermal losses between bomb calorimeter and surrounding. For that some Saw dust are introduced in the outer jacket of the present calorimeter which was previously designed only for filling with water (water jacket). For assessing the effect and significance of these selected insulations on energy equivalent of bomb calorimeter, experiments and calculation have been done with same fuel (Benzoic Acid). In other words, we want to prove that when heat transfer between system and surrounding is less, energy equivalent of bomb calorimeter would be lesser. Experiments were carried out on bomb calorimeter with four types of jackets which are filled with water (Thermal conductivity – 0.56), glass wool (Thermal conductivity – 0.04), and saw dust (Thermal conductivity – 0.08). Some modification work on existing bomb calorimeter had to be done so that selected insulations can be installed as desired in the apparatus for experiments.

The experiment was conducted for testing a locally assembled combine implement used for open furrow, planting and fertilizing under different machinery unit speeds. New Holland TD80 tractor was used in this study. Three machinery speeds included 6.26, 7.44 and 9.53 km?hr which represent main plot and two Furrow depths included 5-15 and 15-25 cm which represent sub plot were used in this study. Field efficiency, Leaf area, 100 seed weight, percentage of oil in maize and maize yield was measured in this experiment. Split plot design under Randomized Complete block design with three replication was used in this study. Least significant differences (L.S.D) under 0.05 level was used to compare the mean of treatment. The results can be summarized as Fallow: 9.53 km ? hr speed gave lower field efficiency stood 63.45% and higher maize yield stood 9.65 t ?h. 5 - 15 cm furrow depth gave higher field efficiency stood 69.01% and greater leaf area stood 0.57 m2 while 15-25 cm furrow depth gave higher maize yield stood 5.23 t ?h. The interaction between speed and furrow depth, has significant effect on all plant properties except 100 seed weight and percentage of oil in maize.Using the locally assembling combine implement for planting corn, fertilizing and open furrows is successfully done. 

Adhesive joints are used in a wide range of industrial applications due to their advantages over other joints. The crack propagation analysis in an adhesive joint is very important for its sustained performance. The Cohesive zone model (CZM) is found to be effective in this area due to its advantage over traditional methods. An overview of the CZM, usage with Finite Element Analysis (FEA), comparison with other methods, and implementation by back face strain (BFS) technique are reviewed in a proportional manner

The optimization of computer numerical control(CNC) boring operation parameters for aluminum alloy 6063 T6 using Taguchi and Grey Relational Analysis(GRA) optimization technique. Machining industry is playing a crucial role in the present manufacturing scenario and boring is an operation which is quite highly used nowadays to enlarge and achieve greater accuracy of the internal holes. In the present work an attempt is made to select the combination of optimum cutting parameters which results in better surface finish (minimum surface roughness i.e. Ra and Rq) and Circularity (Cr). Machining with optimum cutting parameters will result in minimum machining time and enhance the productivity. Three parameters viz. cutting speed, feed and depth of cut of boring bar has been taken as control factors. The cutting trials are performed as per Taguchi L27(3^3) orthogonal method to deal with the response from multi-variables. Taguchi orthogonal array is designed with three levels of boring parameters with the help of software Minitab 16. Grey Relational Analysis is performed for finding out the optimal parameter setting for the Al alloy 6063 T6 material. Additionally, for analyzing the data, the analysis of variance (ANOVA) technique is used to find the significant factors and their individual contribution in the response function i.e. surface roughness and Circularity.

Musculoskeletal disorders (MSDs) are surrounded by the most common work-related problem in India. In an Indian manufacturing industry most of the work is still carried out manually hence issues of work related musculoskeletal disorders and injury in different sites of the body are prominent. Postural analysis using Rapid entire body assessment (REBA), Rapid upper limb assessment (RULA) indicates that the workers are working above the secure limit. The presents study is focused on posture analysis of the workers working in small scale manufacturing industry. The study was conducted on 15 workers engaged in small scale manufacturing industry Wardha (Maharashtra, India). Video tape on different activities of the workers was done and then images were cropped from it for the analysis. This study presents assessment of work posture of worker engaged in different activities of small scale manufacturing industry. Posture analysis tools REBA and RULA method both software as well as worksheet were used. The results of REBA showed that some of the workers were under lower levels and majority at high risk levels. Further the results of RULA showed that majority of the workers were under high risk levels and required immediate change. It was concluded that; there is a lack of ergonomics social contact and understanding in small scale manufacturing industries (SSMIs). Postural analysis using REBA, RULA indicates that the workers are working above the secure limit. A major quantity of the workers is working in awkward postures. Thus the workers are under moderate to high risk of Musculoskeletal disorders (MSDs).

In this study an exergy analysis of 75 MW gas turbine is carried out. Exergy analysis based on second law was applied to the gas cycle and individual components through an off design point modeling approach. The analysis shows that the highest exergy destruction occurs in the combustion chamber (CC), and the gas turbine is significantly affected by the ambient temperature; increase in temperature leads to decrease in GT power output. The compressor has the largest exergy efficiency of 99% as compared to the other components (combustion chamber – 76%, Turbine – 95%). The highest destruction in exergy was recorded in the combustion chamber. As a result of this destruction, 2.23kJ of energy is lost in every 1MW output of power produced by the plant.

A non-linear cumulative fatigue model was developed for estimating the fatigue life of high strength aluminum alloy 7049 in high cycle fatigue (HCF) and low cycle fatigue (LCF) regimes with different laser surface coatings. These coatings are water laser peening and the black paint laser peening (bPLP). The results of the application the new non-liner model to the experimental data that the proposed model is quite applicable for interaction cumulative fatigue with laser coating. The paper also indicated that the fatigue limit increased by 2.59 due to bpLp while it reduced by 2.3 due to WLP.The new non linear model showed satisfactory prediction for bpLp cumulative fatigue loading.