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Numerical investigation of Transient Temperature Field on the Selective Laser Melting process with Al6063
摘要： The finite element simulation of the selective laser melting process with Al6063 metal powder was carried out by using ABAQUS. The loading of the laser Gaussian moving heat source is realized, and a model of the three-dimensional transient temperature field is established. The effects of scanning speed and scanning pitch on temperature distribution and temperature changes on different scanning channels were investigated. The simulation results show that due to the heat accumulation effect and heat conduction, the previous scan will have effect on the surrounding powder, which results the rise of temperature. Different scanning speed and the scanning pitch have influence on the temperature distribution. As the scanning speed increases, the temperature gradually decreases, and the increase in the scanning pitch also lead to lower temperature of the powder layer.
关键词： Finite Element Simulation,Transient Temperature Field,ABAQUS,Selective Laser Melting,Al6063
更新于2025-09-12 10:27:22
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Laser metal deposition of Ti-6Al-4V alloy with beam oscillation
摘要： One of the most prevalent problems of additive technologies is the improvement of process efficiency at the expense of increase in mass deposition rate and reduction of postprocessing time. Deposition rate can be improved by the modification of the shape and size of the molten pool through the optimization of laser beam power distribution. Time and cost of postprocessing depend on the surface roughness requirements and presence of macroscopic waviness. Beam oscillation can help to solve this problem. Laser metal deposition with linear beam oscillation was studied. Effects of numerous process parameters on pool shape and size was analysed by simulation. The heat conduction problem was solved analytically by Green’s function method. Temperature fields due to moving normally distributed strip heat sources were studied. It was established that on increasing the oscillation amplitude up to laser beam radius the heat flux of normally distributed strip heat source decrease rapidly to 53%. Greater the beam radius, the less effect of amplitude on the peak value of molten pool width and lower allowable oscillation amplitude. Microscopic examination revealed that beam oscillation promotes obtaining smooth wall surface without any macroscopic waviness.
关键词： surface waviness,titanium alloy,beam oscillation,temperature field,laser metal deposition
更新于2025-09-12 10:27:22
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Influence of oscillation frequency and focal diameter on weld pool geometry and temperature field in laser beam welding of high strength steels
摘要： As weld pool geometry and thermomechanical strains are known to affect formation of solidification cracks, the influence of a superimposed beam oscillation on these characteristics is investigated for this paper. In this context the effects of the oscillation frequency and focal diameter on the weld pool and temperature field are determined by means of infrared thermography. As a result an increase of the weld pool size for larger focal diameters and a more even shape of the seam edges for higher frequencies can be identified.
关键词： infrared thermography,beam oscillation,laser beam welding,solidification conditions,temperature field,weld pool geometry,high strength steels
更新于2025-09-12 10:27:22
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Investigation of a passively Q-switched Raman laser at 1176?nm with Nd3+:YAG/Cr4+:YAG/YAG composite crystal and a coupled cavity
摘要： To reduce the thermal lens effect and increase the efficiency, a composite crystal of Nd3+:YAG/Cr4+:YAG/YAG and a coupled cavity structure were employed in our passively Q-switched YVO4-based Raman laser system. Both the simulation and the experiment results showed that the undoped YAG crystal bonded in the end-face of Cr4+:YAG crystal can speed up the heat transfer of Cr4+:YAG crystal and reduce the temperature difference between its side surfaces and the center significantly, and the coupled cavity structure can improve the laser performance, especially at high pump power. The maximum output power of Raman laser of 0.92 W at 1176 nm was obtained with an optical-to-optical efficiency of 11.51%. The corresponding repetition rate and the pulse width is 53.5 kHz and 3.22 ns, respectively.
关键词： Composite crystal,Passively Q-switched,Temperature field,Coupled cavity,Raman,Finite element method
更新于2025-09-12 10:27:22
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Residual stress and welding distortion of Al/steel butt joint by arc-assisted laser welding-brazing
摘要： The thermo-elastic?plastic finite element method (FEM) is used to simulate the thermo-mechanical behavior of Al/steel tungsten inert gas (TIG) arc-assisted laser welding-brazing (A-LWB) butt joint. The influence of material nonlinearity, geometrical nonlinearity and work hardening on the welding process is studied, and the differences in the welding temperature field, residual stress and welding distortion by A-LWB and by single laser welding-brazing (SLWB) are analyzed. The results show that the thermal cycle, residual stress distribution and welding distortion by the numerical simulation are in good agreement with the measured data by experiments, which verifies the effectiveness of FEM. Compared with the SLWB, A-LWB can make the high-temperature distribution zone of weld in width direction wider, decrease the transverse tensile stress in the weld and reduce the distribution range of longitudinal tensile stress. And the welding deformation also decreases to some extent.
关键词： arc-assisted laser welding-brazing (A-LWB),residual stress,welding distortion,Al/steel,temperature field,finite element method (FEM)
更新于2025-09-12 10:27:22
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Evaluation of Assembly Gap from 3D Laser Measurements via FEA Simulation
摘要： This study evaluated the characteristics of temperature field distribution of the concrete box girder based on the middle bridge of Xiaosha River, and the effects of temperature in severely cold area were determined through experiments and finite element model (FEM) analysis. An FEM model of the concrete box girder considering the temperature field was established based on heat transfer theory to verify the accuracy of the model. Moreover, the calculation of the vertical temperature distribution and the temperature distribution along the web plate was conducted. The distribution along the through-thickness direction of the bottom plate and the temperature drop caused by cold waves was evaluated. Results suggest that the published codes and guidebooks were relevant. The effect of the most unfavorable condition of temperature load was also calculated. The result drawn from this research shows that the distribution of temperature field at the cross sections in the severely cold area differed greatly from that in the current code. However, the temperature difference in the top flange was not evident, whereas it was much larger in the bottom flange. The temperature in the web was higher than that in the top flange under solar radiation and was lower during cooling. The results of the temperature effect were much more critical than the result calculated using the vertical temperature gradient in the current code. The tensile stress produced by temperature load may cause cracks. Consequently, sufficient attention should be paid to the damage of thermal effects when calculating the concrete box girder in the northwest of the severely cold area.
关键词： concrete box girder,temperature effect,temperature field distribution,FEM,severely cold area,bridge engineering
更新于2025-09-11 14:15:04