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2 Journal of Achievements in Materials and Manufacturing Engineering

2 2006

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Numerical thermodynamic field modeling of a metallic substance during laser welding

Achab L., Amara E. H., Mebani N., Allalou N., Hamadi F.

Journal of Achievements in Materials and Manufacturing Engineering

2006

Vol. 15, nr 1-2

94--99

Purpose: A simplified numerical model which predicts the molten zone thermodynamics, resulting from laser irradiation is developed. Design/methodology/approach: The treatment of this problem is founded on the resolution of the dynamic and thermal flows differential equations, by taking into account the effects of material fusion. Numerical simulations of this steady two-dimensional flow have been carried out using the commercially available software FLUENT. Findings: The proposed numerical study allows us to deduce the thermal and dynamic characteristics of the molten zone, as well as to relate the operating parameters such as the welding speed and the laser power to the form and the dimension of the molten zone. Research limitations/implications: The experimental studies performed on the influence of the operating parameters on the quality of the weld joints produced on work-pieces would be very costly and time-consuming and in more cases, it is difficult to access to some physical unknowns. However, by including as much as possible of terms describing physical mechanisms in the general form of the equations, one can model more on less accurately the welding process. Practical implications: This initial study has produced some encouraging evidence for the capacity of FLUENT in simulating the key features of laser welding treatment. Originality/value: In our contribution, the introduction of the enthalpy-porosity formulation has been used to obtain the geometry of a fused zone, as a function of the operating parameters. The numerical results have shown, that by a proper choice of the laser power and the welding speed, the desired morphology and fineness may be incorporated into the alloyed zone.

Numerical modelling of the laser cladding process using a dynamic mesh approach

Amara E. H., Hamadi F., Achab L., Boumia O.

Journal of Achievements in Materials and Manufacturing Engineering

2006

Vol. 15, nr 1-2

100--106

Purpose: In this paper, a tridimensional modelling of laser cladding by powder injection is developed. Design/methodology/approach: In our approach, the task consists in the numerical resolution of the governing equations including heat transfer and flow dynamic assuming an unsteady state. The related differential equations are discretized using the finite volume method, allowing to obtain an algebraic set of equations. the clad formation is simulated by considering the finite volume mesh deformation. Findings: The shape of the deposited layer is determined as a function of the operating parameters related to the laser beam, the powder, the sample, and the environing atmosphere. Research limitations/implications: By including as much as possible of terms describing physical mechanisms in the general form of the equations, one can model more accurately the cladding process. Afterwards, a validation with experimental results must be done. Practical implications: The comprehension of the occurring physical processes would allow the enhancing of the products quality, the process can then be optimized since predictions on the results to be obtained can be made for given operating parameters. Originality/value: In our contribution, the introduction of the dynamic mesh method involving the use of user defined functions (UDF) in the calculation procedure, have allowed to follow the variation of the cells volume and then to obtain the clad profiles as a function of the operating parameters.