temperature field

摘要： The process parameters of laser additive manufacturing have an important influence on the forming quality of the produced items or parts.In the present work,a finite element model for simulating transient heat transfer in such processes has been implemented using the ANSYS software,and the temperature and stress distributions related to 316L stainless steel thin-walled ring parts have been simulated and analyzed.The effect of the laser power,scanning speed,and scanning mode on temperature distribution,molten pool structure,deformation,and stress field has been studied.The simulation results show that the peak temperature,weld pool size,deformation,and residual stress increase with an increase in laser power and a decrease in the scanning speed.The scanning mode has no obvious effect on temperature distribution,deformation,and residual stress.In addition,a forming experiment was carried out.The experimental results show that the samples prepared by laser power P=800 W,V=6 mm/s,and the normal scanning method display good quality,whereas the samples prepared under other parameters have obvious defects.The experimental findings are consistent with the simulation results.

摘要： In recent years,due to the rapid increase in the number of vehicles in the world,the traditional vehicles using gasoline or diesel as energy have led to serious air pollution and energy depletion.It is urgent to develop practical clean energy vehicles.The performance of electric vehicle depends on the power battery pack.The working temperature of the battery pack has a great impact on the performance of the battery,so it is necessary to carry out thermal management on the battery pack.Taking a lithium-ion battery as the research object,the temperature field of the battery pack in the charge and discharge state is simulated and analyzed by using CFD simulation software in the way of air cooled heat dissipation,so as to understand the influencing factors of uneven temperature field.At the same time,the development trend of battery temperature can be well predicted through simulation,so as to provide theoretical basis for the design of battery pack.

摘要： Before 2008,the number of surface observation stations in China was small.Thus,the surface observation data were too sparse to effectively support the High-resolution China Meteorological Administration’s Land Assimilation System(HRCLDAS)which ultimately inhibited the output of high-resolution and high-quality gridded products.This paper proposes a statistical downscaling model based on a deep learning algorithm in super-resolution to research the above problem.Specifically,we take temperature as an example.The model is used to downscale the 0.0625°×0.0625°,2-m temperature data from the China Meteorological Administration’s Land Data Assimilation System(CLDAS)to 0.01°×0.01°,named CLDASSD.We performed quality control on the paired data from CLDAS and HRCLDAS,using data from 2018 and 2019.CLDASSD was trained on the data from 31 March 2018 to 28 February 2019,and then tested with the remaining data.Finally,extensive experiments were conducted in the Beijing-Tianjin-Hebei region which features complex and diverse geomorphology.Taking the HRCLDAS product and surface observation data as the"true values"and comparing them with the results of bilinear interpolation,especially in complex terrain such as mountains,the root mean square error(RMSE)of the CLDASSD output can be reduced by approximately 0.1°C,and its structural similarity(SSIM)was approximately 0.2 higher.CLDASSD can estimate detailed textures,in terms of spatial distribution,with greater accuracy than bilinear interpolation and other sub-models and can perform the expected downscaling tasks.

摘要： Freeze-sealing pipe roof method is applied in the Gongbei tunnel,which causes the ground surface uplift induced by frost heave.A frost heaving prediction approach based on the coefficient of cold expansion is proposed to simulate the ground deformation of the Gongbei tunnel.The coefficient of cold expansion in the model and the frost heaving rate from the frost heave test under the hydration condition can achieve a good correspondence making the calculation result closer to the actual engineering.The ground surface uplift along the lateral and longitudinal direction are respectively analyzed and compared with the field measured data to validate the model.The results show that a good agreement between the frost heaving prediction model and the field measured data verifies the rationality and applicability of the proposed model.The maximum uplift of the Gongbei tunnel appears at the center of the model,gradually decreasing along with the lateral and longitudinal directions.The curve in the lateral direction presents a normal distribution due to the influence of the constraint of two sides,while the one along the lateral direction shapes like a parabola with the opening downward due to the temperature field distribution.The model provides a reference for frost heaving engineering calculation.

摘要： In this paper,a new storage method for the three-dimensional temperature field data based on artificial neural network(ANN)was proposed.A multilayer perceptron that takes the coordinate(x,y,z)as inputs and temperature T as output,is used to fit the three-dimension-al welding temperature field.Effect of number of ANN layers and number of neurons on the fitting errors is investigated.It is found that the errors decrease with the number of hidden layers and neural numbers per layers generally.When the number of hidden layers increases from 1 to 6,the maximum temperature error decreases from 74.74°Cto less than 2°C.The three-dimensional temperature field data is obtained by finite element simulation,and the experimental verification is completed by comparing the simulation peak temperatures with the measured results.As an example,an ANN with 4 hidden layers and 12 neurons in each layer were applied to test the performance of the proposed method in storage of the three-dimensional temperature field data during friction stir welding.It is found that the average error between the temperature data stored in ANN and the original simulation data that stored point-by-point is 0.517°C,and the error on the maximum temper-ature is 0.193°C,while the occupied disk space is only 0.27%of that is required in the conventional point-by-point storage.

摘要： With the growing applications of nanofluid flame, the monitoring and controlling of its combustion process is of paramount importance. Thus, it is necessary to develop diagnosing methods which can simultaneously image important parameters such as temperature and volume fractions of soot, metal-oxide nanoparticles. Tomographic emission spectroscopy is an effective method which has been proposed for this purpose. However, the inversion process was only reported with least-squares QR decomposition(LSQR) so far and there are numerous well-established reconstruction algorithms which have not been utilized yet.Thus, this work aims to perform systematic comparative studies on several representative algorithms for the inversion process. In the simulative studies, algorithms including Tikhonov regularization, algebraic reconstruction technique(ART), LSQR,Landweber algorithm, maximum likelihood expectation maximization(MLEM), and ordered subset expectation maximization(OSEM) were discussed. The effects of the number of iterations, the signal-to-noise ratio, and the number of projections and the calibration error in projection angles on the performance of the algorithms were investigated. Advice on selecting the suitable algorithms under different application conditions is then provided according to the extensive numerical studies.

摘要： In the paper, the finite element model(FEM) of wire arc additive manufacturing(WAAM) by TIG method was established by the ABAQUS soft, and the phase transformation latent heat was considered in the model. The evolution rules of temperature field at the interlayer with the cooling time of 10 s, 30 s and 50 s were obtained by the model. The WAAM experiment were performed by 5356 aluminum alloy welding wire with Φ1.2 mm, and the simulated temperature field were varified by the thermocouple. The result shows that the highest temperature at the molten pool center increases with the increased interlayers at the same interlayer cooling time;the highest temperature drops gradually and the decline is smaller with the increased interlayer cooling time at the same layer. No remelting occurs at the top layer, and at least two remelting times occur in the other layers, resulting in complex temperature field evolution.

摘要： In order to ensure the service life of pavement in cold areas, this paper simulates the temperature field and stress field of pavement at high temperature of 60˚C and low temperature of -30˚C based on ANSYS software, and analyzes the changing trend of temperature of each layer with time and the temperature stress caused by it using the time-incremental finite element method. The results show that when the temperature is higher than 0˚C, the temperature between layers of the structure and the surface temperature shows an increasing trend. On the contrary, when the temperature is lower than 0˚C, it shows a decreasing trend. The more drastic the temperature change is, the greater the temperature stress of the pavement will be, which is easy to cause road structure diseases. When the temperature difference of pavement reaches 90˚C, the change of temperature stress between layers of road structure has a significant effect on the daily evolution of pavement.

摘要： The freezing of soil containing a liquid is a complex transient heat conduction problem involving phase change and release or absorption of latent heat.Existing efforts have essentially focused on theoretical research and numerical simulations.In the present study,the problem is approached from an experimental point of view using the so-called“freezing model test”method.In particular,in order to establish a precise relationship between the model and the prototype,a temperature similarity criterion is derived using the condition of an equal number of Kosovitch.Similarity is also established with respect to other aspects.A similarity criterion for the water field is determined on the basis of relevant partial differential equations.Analogous criteria for the stress field and load are derived using an elastic model.The validity of this approach is experimentally verified.The research results provide a practical and reasonable method for calculating the parameters for preparing model soils.They also constitute a theoretical basis and a technical support for the design and implementation of a water-heat-force similarity coupled framework.

摘要： To investigate the influence of temperature field of friction stir welding(FSW)2219 aluminum alloy thick plate,and to achieve effective prediction of temperature field,the authors establish a three-dimensional numerical simulation model of FSW 18 mm thick 2219 aluminum alloy based on ABAQUS/CEL,considering the morphological characteristics of the tool pin.The simulations of plunging,dwelling,and welding stages are achieved.The distribution of temperature and temperature cycle curve of characteristic points in welding process are obtained.The validity of the simulation results is verified by experiments.The influence of the tool-rotational speed and welding speed on temperature field is explored.The work lays a foundation for the prediction and control of temperature field in FSW medium thickness 2219 aluminum alloy,and provides reference for selection of welding parameters to ensure high quality welding of fuel tank of heavy-lift rocket.