S.P. Sivapirakasam

Multi-attribute decision making for green electrical discharge machining

This paper aims to develop a combination of Taguchi and fuzzy TOPSIS methods to solve multi-response parameter optimization problems in green manufacturing. Electrical Discharge Machining (EDM), a commonly used non-traditional manufacturing process was considered in this study. A decision making model for the selection of process parameters in order to achieve green EDM was developed. An experimental investigation was carried out based on Taguchi L9 orthogonal array to analyze the sensitivity of green manufacturing attributes to the variations in process parameters such as peak current, pulse duration, dielectric level and flushing pressure. Weighing factors for the output responses were determined using triangular fuzzy numbers and the most desirable factor level combinations were selected based on TOPSIS technique. The model developed in this study can be used as a systematic framework for parameter optimization in environmentally conscious manufacturing processes.

Investigations on emission characteristics of the pongamia biodiesel–diesel blend fuelled twin cylinder compression ignition direct injection engine using exhaust gas recirculation methodology and dimethyl carbonate as additive

Experiments were carried out on a twin cylinder direct injection compression ignition engine using pongamia biodiesel–diesel blend as fuel with exhaust gas recirculation (EGR) and dimethyl carbonate (DMC) as additive. The experimental results showed that pongamia biodiesel–diesel blend fuelled engine with EGR and DMC can simultaneously reduce smoke and nitric oxide (NOx) emission. The NOx emission was reduced by about 17.68% for 10% of EGR introduction and about 13.55% increase in smoke emission. When dimethyl carbonate was added with EGR, the engine emits lower smoke with lesser NOx emission, and it showed that the smoke reduction rate had a linear relationship with DMC percentage. The carbon monoxide (CO) and hydrocarbon (HC) emissions also decreased when DMC was added. However, the addition of DMC with EGR caused an increase in both BSEC and BTE.

Thermal hazards of cracker mixture using DSC

DSC studies of cracker mixtures of different compositions of potassium nitrate, sulphur and aluminum have shown some critical characteristics either with the increase or decrease in the composition of the components. Specifically, sulphur composition below 8% showed no exothermic activity. The studies revealed that a minimum of 11% to a maximum of 17% of sulphur is required for good cracking characteristics. The kinetics of decomposition of cracker mixture is carried out employing DSC multiple heating rate kinetic method. Increase in sulphur content decrease the energy of activation facilitating easy ignition of the cracker mixtures. Arrhenius parameters for cracker mixture decomposition are reported in this paper.

A comparative evaluation of Al2O3 coated low heat rejection diesel engine performance and emission characteristics using fuel as rice bran and pongamia methyl ester

In this study, for the first time, a nanoceramic Al2O3 was used as a coating material in the low heat rejection engine concept. Experiments were conducted on single cylinder, four stroke, water cooled, and direct injection diesel engine. First, the engine was tested at different load conditions without coating. Then, combustion chamber surfaces (cylinder head, cylinder liner, valves, and piston crown face) were coated with nanoceramic material of Al2O3 using plasma spray method. Comparative evaluation on performance and emission characteristics using fuel as rice bran methyl ester, pongamia methyl ester, and biodiesel/diesel fuel mixtures was studied in the ceramic coated and uncoated engines under the same running conditions. An increase in engine power and a decrease in specific fuel consumption, as well as significant improvements in exhaust gas emissions (except NOx) and smoke density, were observed in the ceramic coated engines compared with those of the uncoated engine.

Studies on biodiesel production and its effect on DI diesel engine performance, emission and combustion characteristics

Production of biodiesel from waste cooking oil was studied by experimental investigation using response surface methodology, specifically D-optimal design consisting of two levels. Waste cooking oil methyl ester (WCO-ME) produced under optimum transesterification process parameters was used in a direct injection diesel engine to evaluate the performance, emission and combustion characteristics at a constant speed of 1500 rpm. Results revealed that the biodiesel resulted in decreased brake thermal efficiency by 6% and higher brake-specific energy consumption of 25.9% when compared to diesel at 100% load condition. Carbon monoxide (CO), unburnt hydrocarbon, nitric oxide (NO) emission and smoke emission of WCO-ME decreased by 43.3%, 52.7%, 23% and 15.5%, respectively, compared to diesel. WCO-ME exhibited lower heat release rate, shorter ignition delay of 10.9°CA and slightly longer combustion duration of 54.4°CA when compared to diesel at same load condition.

Experimental Evaluation of Whole Body Vibration Exposure from Tracked Excavators with Hydraulic Breaker Attachment in Rock Breaking Operations

Ever expanding technological growth has led to an increase in the use of tracked excavators for construction, demolition, material handling, rock breaking etc. Excavator operators are exposed to a variety of risk factors that may lead to health problems. A major health hazard among operators is whole-body vibration. Human response to vibration is very complex and nonlinear. Whole Body Vibration in the range of 2 to 30 Hz corresponds to most of the resonant responses of various organs and parts of the human body. The objective of this paper is to assess whole body vibration for the tracked excavator with hydraulic breaker. The job safety analysis conducted through questionnaires for different industrial vehicle operators revealed the presence of a health risk among the operators in rock breaking machinery. To quantify the level of vibration, field tests are performed on four tracked excavators with hydraulic breaker attachments in two different work locations. Accelerometer, a real-time signal conditioning / processing and PULSE data acquisition software are used for vibration measurement. The frequency of vibration exposure is observed to be between 6.8 and 12 Hz. Acceleration levels measured were in the range of 0.87 −2.2 m/s2 for a tracked excavator operator with breaker. The total vibration exposure calculated was between 0.621 and 1.932 m/s2. The vibration dose value recorded was 17.6 −62.72 m/s1.75. Whole body vibration exposure of the breaker operator was much higher and lies beyond the upper limit as given in ISO 2631–1. The ranges of vibration parameters measured were concomitant with frequent lower back pain, other muscular-skeletal injuries like leg pain etc which are prevalent among these operators.

Effect of Process Parameters on the Breathing Zone Concentration of Gaseous Hydrocarbons—A Study of an Electrical Discharge Machining Process

ABSTRACT The purpose here was to study the effect of process parameters on breathing zone concentrations of gaseous hydrocarbons generated from an Electrical Discharge Machining process. Peak current, pulse duration, dielectric level above the spark location, and flushing pressure were the process parameters considered. Gas chromatography coupled with mass spectrometry (GC/MS) was used to analyze the hydrocarbon components of gaseous emission. Peak current and pulse duration appeared the most significant. A significant fraction of emission was of reaction products of dielectric fluid that included high molecular weight hydrocarbons, branched chain hydrocarbons and other reaction products. Possible measures to control and minimize risk of exposure were outlined as well.

Application of Taguchi method in the optimization of process parameters for a sol–gel-derived nano-alumina film

In this study, the Taguchi method is used to find the optimal process parameter combinations for realizing both lower film thickness and crystallite size and higher film thickness and crystallite size in a nano-alumina film prepared by sol–gel route. The process parameters evaluated were the molar concentration of the sol, dipping time, and sintering temperature. An orthogonal array, signal-to-noise ratio, and an analysis of variance were employed to analyze the effect of these process parameters. Surface profile measurement and X-ray diffraction techniques were used to measure the film thickness and crystallite size respectively. The analysis showed that the molar concentration of the sol was the most significant parameter on the film thickness and crystallite size, followed by dipping time and sintering temperature. Experimental results are supplied to exemplify the strength of this approach.

Mathematical modelling and optimisation of laser welding of butt joints

Laser welding is characterised by its high power density and concentrated heat input. The weld bead profile of laser welding depends on various parameters and these parameters are to be selected correctly to obtain the desired output. As the trial and error method for selecting weld parameters is very costly, suitable analytical methods has to be established for selecting optimum parameters for welding. In this paper the influence of laser welding parameters on the weld bead profile of butt joints are analysed and discussed. The experimentation is performed based on Box-Behnken design. Mathematical modelling is done to predict the responses and the adequacy of the model is tested using the analysis of variance. Numerical and graphical optimisation techniques are used to find the optimum process range which will improve the weld quality.

Segmental vibration transmissibility of seated occupant from lumped parameter models

One of the important parameters for the comfort of a seated occupant of a vehicle is the dynamic parameter. The effects of vibration depend on biomechanical characteristics, transmissibility (TR) and apparent mass. The range of input vibration at the seat and TR at the driving frequency will decide the magnitude of the displacement at any point of the human occupant. The most preferred form of biomechanical model for unidirectional whole body vibration is the lumped parameter model. Lumped parameter models are formulated by number of masses depending on the number of degrees-of-freedom (d.f.). The objective of this work is to study the vibration TR by developing the equations of motion (EOM) for different d.f. models for the seated occupant. Then the generated equations of motion for lumped parameter models are solved using the frequency domain technique. In this paper two, four, seven and 11 d.f. models are considered. The TR values are determined by solving the derived parameters using the MATLAB program. The maximum seats to head TR in the case of two, four, seven and 11 d.f. are obtained at the frequency of 2 Hz, 2.5 Hz, 3.15 Hz, and 4 Hz respectively. The TR obtained from models is compared with real time experimental results. The comparison shows a better fit for the TR obtained from the four and seven d.f. models. There is a wide deviation from the TR observed with two and 11 degrees of models when compared with experimental results of the past literature.