In this paper, a three-dimensional finite element model is developed to compute thermal phenomena of 0.5 mm thick Hastelloy C-276 alloy sheets during pulsed laser beam welding (PLBW). Temperature-dependent thermal properties of Hastelloy C-276 alloy, effect of latent heat of fusion, and the convective and radiative boundary conditions are taken into account in the model. The space-time temperature distributions in a butt-joint weld produced by the PLBW process are predicted from the beginning of welding to the final cooling. The heat input to the model is assumed to be a double ellipsoid heat source. The finite element calculations are performed by using ANSYS code with the parametric design capabilities. Experiments were carried out to determine the temperature evolution during welding and to measure the cross section profile of the weld bead. By comparing the simulation results with the corresponding experimental findings, it is found that they are in a good agreement. The validity and applicability of the numerical simulation model are confirmed.
Multiple-scale community of complex networks has attracted much attention. For the problem, previous methods can not investigate multiple-scale property of community. To address this, we propose a novel algorithm (h_LPA) to detect multiple-scale structure of community. The algorithm is a heuristic label propagation algorithm associated with spectral analysis of complex networks. Label updating strategy of h_LPA is combined with heuristic function from the perspective of networks dynamics. The heuristic function further improves the dynamic efficiency of h_LPA. Extensive tests on artificial networks and real world networks give excellent results.
The Nd:YAG laser welding experiments of Hastelloy C-276 was presented and the results of experiments were discussed which reflect the rise of electric resistivity of the sample. In addition, a mathematic model of 2-D nonlinear eddy current field for motor of the nuclear reactor coolant pump with the Hastelloy C-276 can was simulated which provides the concrete effect of electric resistivity change on the eddy current losses of cans. It was found that the eddy current losses of the motor can were decreased as the increase of electric resistivity of can. Then, the advantage of laser welding on the molding of motor can was discussed which not only does not destroy the electric performance of Hastelloy C-276 but enhances it and declines the eddy current losses of can forming with it.
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