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Abstract: In this research, a systematic investigation on laser transmission contour welding process is carried out using finite element analysis (FEA) and design of experiments (DoE) techniques. First of all, a three-dimensional thermal model is developed to simulate the laser transmission contour welding process with a moving heat source. The commercial finite element code ANSYS® multi-physics is used to obtain the numerical results by implementing a volumetric Gaussian heat source, and combined convection–radiation boundary conditions. Design of experiments together with regression analysis is then employed to plan the experiments and to develop mathematical models based on simulation results. Four key process parameters, namely power, welding speed, beam diameter, and carbon black content in absorbing polymer, are considered as independent variables, while maximum temperature at weld interface, weld width, and weld depths in transparent and absorbing polymers are considered as dependent variables. Sensitivity analysis is performed to determine how different values of an independent variable affect a particular dependent variable. [Copyright &y& Elsevier]

Abstract: In this paper, simultaneous laser transmission welding process is systematically investigated via process modeling, using an FEM and RSM combined approach. The objective of the present research is to study the effects of process parameters on the temperature field and weld bead dimensions. The thermal field is simulated by solving a three dimensional transient heat diffusion equation with temperature dependent material properties using the ANSYS® multi-physics. Response surface methodology is then applied for developing mathematical models based on simulation results. The second order equations developed by RSM can predict the values of the responses with significant accuracy. The effect of parameters and their interactions on the responses are studied using the developed response surface models. The mathematical models are further used in search of the optimal process window for obtaining an acceptable weld. The graphical optimization results into a couple of overlay contours plots, which allow quick visual inspection of the area of feasible response values in the factor space to choose the favorable welding parameter combination. [Copyright &y& Elsevier]

• Carried out Nd:YAG laser micro-drilling operations on gamma titanium aluminide. • Observed quality characteristics of through micro-drilled holes. • Proposed a combined Fuzzy-TOPSIS and RSM technique for parametric optimization. Multi criteria decision making methods and response surface methodology based approaches are invariably utilized in improvement of quality in several manufacturing industries. This paper presents the technique to determine optimal process parameters during micro-drilling using Nd:YAG laser source on gamma titanium aluminide alloy using fuzzy-TOPSIS (fuzzy-technique for order preference by similarity to ideal solution) and RSM (response surface methodology) together. A new alloy, Gamma-titanium aluminide (Ti-44.5, Al-2, Cr-2, Nb-0.3B (at%)) has been chosen for experimentation. This material possesses desirable qualities like very high hardness, high strength temperature resistant, high yield stress and ultimate strength in tension, good creep, very low density, resistance to oxidation etc., found applications in technologically advanced industries like spacecrafts, aerospace, nuclear power plants, electronics, automobiles etc. A model has been developed which can be used for decision making in identifying the optimum laser parameters like lamp current, pulse frequency, air pressure and thickness of the workpiece, which affect several quality aspects of micro-machined job such as hole circularity at entry, hole circularity at exit and taper of drilled hole. Triangular fuzzy numbers are being utilized to calculate weighting factor of each machining criterion. Also, the combination of most desirable factor levels has been obtained using a fuzzy-TOPSIS method. [ABSTRACT FROM AUTHOR]