Applied Mechanics and Materials Vols. 592-594

Abstract: This paper proposed a response surface methodology technique to optimize the multi-response of wire-cut electric discharge machining process. The machining was done on Al 6063 plate is casted with varying mass of Al₂O₃ (3%, 6%, 9%). Stir casting process is adopted for casting the composite plate. Design Expert is used to identify the effect of key operating factors on output measures such as surface finish and kerf by using Pulse on-time, pulse off-time, servo feed and varying mass of Al₂O₃ (3%, 6%, 9%). Also the distribution of Alumina and Aluminium is examined by microstructure analysis, and the material is tested for its mechanical Properties such as tensile strength and Hardness. We found that with respect to increase in pulse on-time and weight percentage of alumina the Surface roughness and kerf decreased leaving a better finish. Also a comparison has been done between the result obtained through response surface methodology and experimental values which indicates that the experimental values are very much close to the predicted values.

Abstract: In this paper optimization of the electrical discharge machining (EDM) process with multiple performance characteristics based on the orthogonal array with the grey relational analysis was studied and investigated. A grey relational grade obtained from the grey relational analysis is used to solve the EDM process. Optimal machining parameters are determined by considering the grey relational grade as the performance index. The input independent parameters of peak current, pulse on time and pulse off time were examined and optimized on multiple response characters (material removal rate, electrode wear ratio and surface roughness). Experimental results have shown that machining performance in the EDM process can be improved effectively through this approach.

Abstract: In this work, a parameter optimization in turning Inconel 718 for multiple performance characteristics has been attempted. The process parameters viz., cutting speed (v), feed (f) and depth of cut (d) is optimized that minimizes surface roughness (R_a) and tool wear (VB). Response surface methodology (RSM) employing CCD experimental design was used to develop predictive model for R_a and VB. The predictive capability of the model provides the average percentage error as 3.87 % and 5.10% for R_a and VB respectively with maximum percentage error limited to 14.67 %. The data are analysed to study the main effect and interaction effects of machining parameters through surface plot. Feed remains dominating factor. Process parameters are optimized for single and multiple objectives using three different techniques viz., statistical and mathematical approach based desirability analysis (DA) and soft computing based genetic algorithm (GA) and firefly algorithm (FA). The results are compared.

Abstract: The present study ,Sparking parameters namely current (I), pulse on time (t_on), pulse off time (t_off), spark gap and dielectric flushing pressure (P) are optimized with the considerations of multi responses such as Material Removal Rate (MRR), Electrode wear Rate (EWR), of the MoSi₂-SiC intermetallic/ceramic composite are investigated by use of the Taguchi L₁₈ orthogonal array (OA) with grey relational grade analysis was reported.

Abstract: This paper presents a novel approach for the optimization of welding parameters on dissimilar friction stir welded joints between AA6061T-651 and AA7075T-651 aluminium alloys with multiple responses based on orthogonal array by grey relational analysis. Experiments are conducted by varying the welding parameters related to three pin profiles. In this study, welding parameters namely rotational speed, welding speed and pin profiles are optimized with the considerations of multi responses such as ultimate tensile strength and hardness. A grey relational grade is obtained from the grey analysis. Based on the grey relational grade, optimum levels of parameters have been identified and significant contribution of parameters is determined by ANOVA (Analysis of Variance). Confirmation test is conducted to validate the test result. Experimental results have shown that the responses in welding process can be improved effectively through this novel approach.

Abstract: Laminated composite plates are greatly used in many applications where high specific strength and stiffness are mandatory. These structures may have holes in order to accommodate windows and doors if it is used for air craft structures or to provide cables and inspection system if it is used in the applications like power transmission systems and automobiles. The laminated composite plates with holes shall be analyzed using finite element analysis. It is necessary to optimize the parameters like thickness, fiber orientation, material and the stacking sequence to obtain the desired characteristics for these structures. But using finite element analysis makes the process more tedious job. With this in mind it is proposed here to construct the artificial neural network to predict the buckling behavior of the composite plate.

Abstract: The objective of this work is to carry out thermo-elasto-plastic analysis of pulsed Nd-YAG laser-beam butt welding of 304L Stainless Steel sheets using Finite Element Modelling. Thermo-mechanical analysis was done by using commercial Finite Element software SYSWELD. Thermal analysis provided thermal cycles and weld bead geometry. Then using thermo-mechanical analysis, residual stresses and distortion values were estimated. In order to validate the model predictions, a single pass autogenous welding with pulsed laser beam was performed on 304L stainless steel sheets. Thermocouples were used to record temperatures at different places close to the fusion line. Vertical displacements after welding were measured using Vertical height gauge equipment. The longitudinal residual stress after welding was measured using an ultrasonic technique. Metallography was employed to view the cross sections of the weld bead. The Finite Element Analysis results were then compared with experimental results. Thermal cycles, distortion and residual stresses obtained in FEA and experiments were found to be in good agreement.

Abstract: Numerical simulation of heat transfer and fluid flow analysis of laser welding is essential to understand the physics of fluid motion, thermal cycles, heating and cooling rate and its effect on the formation of the final weld bead profile. The fusion geometry, weld thermal cycles, temperature and velocity field will vary depending on the welding process parameters. The influence of process parameters on the formation of weld bead geometry was analyzed in this study. In the simulation a plane Gaussian profile heat source was used to model the laser beam considering the equations of mass, momentum and energy. It was observed that due to the difference in surface tension coefficient the fluid moves from the central region of the molten pool to the outside. Increase in beam power or decrease in welding speed resulted in a high heating rate and less cooling rate due to high heat input. The simulated bead profiles were compared with the experimentally measured profile and was found to be in agreement.

Abstract: A finite element model has been developed utilizing the commercial ANSYS software to determine the temperature distribution & heat affected zone in laser cutting of titanium alloy (Ti-6%Al-4%V).The main aim of this paper is to determine the temperature reached in the vicinity of the location where the laser interaction with the work piece material takes place. This model is based on Fourier law of heat conduction and Gaussian distribution of laser. Temperature dependent thermal and mechanical properties of material are assumed in this analysis. Result obtained are then analyzed and thermal effect is then understood for the effective control of the process.

Abstract: This study investigates about machining practices used worldwide for machining of Inconel 718 super alloy. The effect of machining parameters like cutting speed, feed and depth of cut on machining responses like surface roughness and material removal rate when end milling Inconel 718 is studied using nine trials carried out based on L9 orthogonal array. A Taguchi based grey relational analysis was used for optimisation of machining parameters for high feed end milling operation on Inconel 718. An analysis of variance (ANOVA) was used to find the most significant factor. Validation of results through confirmation tests was performed and experimental results show that surface quality and productivity can be improved efficiently with this approach.