分类： 机械工程 >> 机械制造工艺与设备 提交时间： 2024-03-28
摘要： The heat transfer mechanism andtemperature distributioninlaser weldingapplications have a great impact on the quality of the weld bead geometry, mechanical properties and the resultant microstructure characterizations of the welding process. In this study, the effects of pulsedlaser weldingparameters including the frequency and pulse width on the melt velocity field andtemperature distributionin dissimilarlaser weldingof stainless steel 420 (S.S 420) and stainless steel 304 (S.S 304) was investigated. A comprehensive comparison was conducted through the numerical simulation and artificial neural network (ANN). The results of numerical simulation indicated thatbuoyancy forceandMarangonistress are the most important factors in the formation of the flow of liquid metal. Also, increasing the pulse width from 8 to 12ms due to increasing the pulse energy, the temperature in the center of the melt pool increased about 250°C. This leads to increasing the convective heat transfer in the molten pool and heat affected zone (HAZ). The temperature difference at a distance of 1mm from the beam center at both metals at a frequency of 15 and 20Hz is bout 58 and 75°C, respectively. Furthermore, reducing the frequency to 5Hz, due to diminishment of thermal energy absorption time, has clearly decreased the weld penetration depth in the workpiece. According to the ANN results, increasing both pulse duration and frequency has the significant effect on increasing melting ratio from 0.4 to 0.8 compared to the other input parameters. The ANN results confirmed that under the same input conditions, because of the differences in thermal conductivity coefficient, absorption coefficient and melting point of the two pieces, S.S 304 has experienced higher temperatures about 10% more than S.S 420. Also, among the 13 back propagation learning algorithms, the Bayesian regularization algorithm had the best performance. Among the number of different neurons in the hidden layer, comparison was performed to prevent network overfitting. The maximum relative error of network output data and target data for S.S 304 and S.S 420 temperatures and melting ratio were 7.297, 10.16 and 11.33%, respectively.
分类： 机械工程 >> 机械工程其他学科 提交时间： 2024-03-28
Darius Andriukaitis
Zhixiong Li
Xiaofei Wen
Mustafa Inc
Linxiang Li
Hadi Bagheri
S. Mohammad Sajadi
Chunsheng Yang
摘要： Increasing the transfer (HT) coefficient used in thermal industries is very important. Various methods are used to improve the efficiency of thermal heat HT so that maximum HT takes place in a smaller space. Ethylene glycol (EG) is generally used as an agent for convective HT. EG obtains energy from a hot source and discharges it to the required location. At present, the most consumption of EG is to produce engine cooling fluid. In the upcoming research, the TB of EG fluid in two-dimensional microchannels (MCs) has been investigated using molecular dynamics (MD) simulations, and the effect of variables such as MC dimensions and MC wall temperature (Temp) on the TB of the simulated fluid has been investigated. The results revealed that by increasing the Temp difference of the MC wall from 10 to 50 K, the maximum temperature (Max-Temp) and velocity (Max-Vel) of the target sample increased to 640.94 K and 0.024 Å/ps. It can be concluded that the increase in the cross-sectional area and the wall Temp difference leads to an increase in the HT rate in the MC.
点击量
通过
点击量
下载量
评论
