This study examines the effects of the temperature field on the sensitization of Alloy 690 butt welds fabricated using the gas tungsten arc welding (GTAW) method and the laser beam welding (LBW) ...method, respectively. The welding thermal cycles of the two welding methods are simulated using ANSYS software based upon a moving heat source model and the high-temperature thermal physical property data maintained in the JMatPro database. The validity of the numerical model is confirmed by comparing the simulation results with the corresponding experimental findings. It is found that the agreement between the numerical results for the temperature field and the experimental temperature measurements by utilizing the value of the thermal diffusivity (
α) in the thermal model for the GTAW and LBW weldments. In addition, it is shown that the LBW weldment experiences a more rapid heating and cooling effect than the GTAW weldment, and therefore has both a smaller heat-affected zone (HAZ) and a narrower sensitization region. Overall, the simulation results presented in this study are found to be in good agreement with the experimental findings. Thus, the validity and general applicability of the thermal welding model are confirmed.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Modelling methods for the transient temperature field of wear land on the flank of end mills have been proposed to address the challenges of inaccurate prediction in the temperature field of end ...mills during the high-speed peripheral milling of Ti6Al4V that is a titanium alloy. A transient temperature rise model of wear land on the flank of end mills was constructed under the influence of heat sources in the primary shearing zone (PSZ), rake-chip zone (RCZ), flank-workpiece zone (FWZ), and dissipating heat source. Then the transient temperature field model of wear land on the flank of end mills was constructed. Finally, the transient temperature field model of wear land on the flank of end mills was constructed. Comparison of simulation result and experimental data verified the accuracy of the model. In sum, the proposed model may provide a temperature model support for future studies of flank wear rate in end mill modeling.
In order to exactly master the change rules of brake shoe’s temperature field during hoist’s emergency braking, the theoretical model of three-dimensional (3-D) transient temperature field was ...established according to the theory of heat conduction, the law of energy transformation and distribution, and the operating condition of mining hoist’s emergency braking. An analytic solution of temperature field was deduced by adopting integral-transform method. Furthermore, simulation experiments of temperature field were carried out and the variation regularities of temperature field and internal temperature gradient were obtained. At the same time, by simulating hoist’s emergency braking condition, the experiments for measuring brake shoe’s temperature were also conducted. It is found, by comparing simulation results with experimental data, that the 3-D transient temperature field model of brake shoe is valid and practical, and analytic solution solved by integral-transform method is correct.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The severe aerodynamic heating on the surface of modern hypersonic flight vehicle, that can bring high temperature and large temperature gradients in the structure of the vehicle, will be a challenge ...for the vehicles design and multidisciplinary optimization. The transient thermal environment consists of high temperature and large temperature gradients will generate two important problems related to vehicle structure, namely: 1) the material property, such as elastic modulus, will be degraded at elevated temperature, and 2) the non-uniform thermal stress cased by large temperature gradients will change the stiffness distribution of wing structure, which can make the modal frequencies and shapes of structure changed remarkably. Firstly, the theory and methodology of structure modal analysis in transient thermal environment is outlined. Subsequently, the transient temperature field of structure considering aerodynamic heating is obtained by employing computational technology of aerodynamic heating/structure heat transfer coupling program. Finally, the modal frequencies and shapes of vehicle structure under transient temperature field is calculated based on finite element method (FEM). Based on the analysis and investigation of the simulation results, the influence of the transient thermal environment on structure modal frequency and shape is determined. Furthermore, the investigation of wing structure modal analysis considering aerodynamic heating is an important basis of aerothermoelastic simulation.
In this paper, the transient temperature field around a thermally insulated crack in a substrate bonded to a coating is obtained using the hyperbolic heat conduction model. Fourier and Laplace ...transforms are applied, and the thermal conduction problem is reduced to solving a singular integral equation. Numerical results show that the hyperbolic heat conduction parameters, the heat conductivity of the substrate and coating, and the geometric size of the composite have significant influence on the transient temperature field. In the case of very small time scales, the results predicted by the hyperbolic model are more conservative than that by the parabolic model.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Transient temperature response of a parallel-flow three-fluid heat exchanger with the thermal capacitance of the walls and the longitudinal heat conduction through the walls is investigated ...numerically, by the implicit MacCormack method, for a step change in flow rate of one fluid. The impact of thermal properties of the walls on temperature field is examined. The results of calculations show that as the thermal diffusivity of the walls decreases, the effect of the walls increases.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
According to the structural characteristic of LNG cryogenic storage tank concrete prestressed wall and heat transfer theory, the paper obtain the calculation formula of the temperature field ...distribution, emphasis studying the heat flux distribution along the radial and axial and node temperature distribution of the section nodes for a 160,000 m3 capacity LNG cryogenic tank by ABAQUS. The paper also establish a set of method which is suitable for the temperature field analysis, proof the feasibility of finite element analysis technique in the analysis of the LNG cryogenic storage tank, and have a certain reference for the prestressed concrete walls and insulation layer design of the large LNG storage tank.
In the paper is described the solution of unsteady temperature field of multilayer plane structures. Nonlinear material and thermal properties of each layer for high temperature and fire is used. ...Defining the boundary conditions and calculation of the temperature at the contact material layers of the conditions of equality thermal flux is performed. The compiled program NONSTAC programmed numerical solution of differential equations modified heat conduction Euler and Runge - Kutta method with a variable integration step length. This computer program solves one dimensional temperature distribution. It is possible to input appropriate thermal characteristics as a function of temperature and to take into account heat of hydration development and variation of environment temperature. Calculated temperatures can be used for stress and strain analysis of shallow foundations with slide joint in footing bottom and fire resistance of plate structures.
In order to control the thermal stress of cladding, a numerical simulation of temperature field during multi-track & multi-layer laser metal deposition (LMD) process is developed with ABAQUS based on ...“element birth and death” technology of FEM. The dynamic variances of temperature field and stress field of forming process are calculated with the energy compensation of interaction between molten pool-powder. The temperature field, temperature gradient, thermal stress field and distribution of residual stress are obtained. The results indicate that although the nodes on different layers are activated at different time, their temperature variations are similar. The temperature gradients of samples are larger near the molten pool area and mainly along z-direction.
The current paper forms part of a series of research activities investigating the potential to implement a novel mobile device for marine diesel engine crankshaft journal surface refurbishment using ...laser cladding technology. Currently the laser cladding renovation process is not yet certified and is not an approved repair method for parts with highly stressed zones such as the fillets and bearing surfaces of marine diesel engine crankshafts, due to data deficiency or the absence of a validated method to evaluate high residual stress formation. In the current work, a method is proposed based on 3D transient temperature, calculating the residual stress field in the laser cladding model. The industrial application advantages of such a method are discussed and demonstrated in a case study. Further research campaigns and actions for demonstrating the industrial suitability of this method are discussed. Keywords: Laser cladding; Marine Diesel Engine Crankshaft; Refurbishment Technology; Numerical Calculation; Transient Temperature Field; Transient Residual Stress Field.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
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