The research of the influence of housing material on operation temperature of the idler bearing assembly is presented in this paper. Several radial loads and rotary speeds were applied to the test ...bench to determine the transient temperature field. The results were monitored and recorded for the whole period until the temperature of the assembly reached stationary stage. The FEM model was created where the rolling elements were replaced with the especially designed artificial body, having the shape of irregular ring. It generates heat and connects only those points of the inner and outer ring which are in operating conditions connected with the rolling elements. The experimental results are compared with FEM results. The conclusion is given on suitability of polymer material for this purpose.
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•Set up a decentralized fuzzy inference for estimation of internal thermal excitation.•The inversion method possesses a good anti-ill-posedness character.•The transient temperature of gas cylinder is ...reconstructed by infrared thermography.•The infrared thermography of gas cylinder is collected at the actual inspection site.
The representative composite overwrapped pressure vessel of vehicle-mounted composite compressed natural gas cylinder is taken as the research object. Based on the principle of double decentralized fuzzy inference with a temporal-spatial decoupling characteristic, an inversion scheme is established by which the infrared thermography of cylinder is employed to estimate the transient distribution of internal thermal excitation. In this scheme,the error vector of time series of the finite temperature measurement points on the surface of cylinder is processed by fuzzy inference, and then the transient distribution of internal thermal excitation is estimated. The influence of the number of measurement points and measurement errors on the inversion results is studied through numerical simulation. Furthermore, combined with the on-site gas cylinder inspection process, the internal thermal excitation of cylinder is estimated using the infrared thermography of cylinder under the steam flushing process obtained from the inspection site. According to the inversion results, the transient temperature field of cylinder is reconstructed, and the reliability of reconstruction results is also verified. The results show that under the experimental conditions in this paper, the maximum deviation of the surface temperature reconstruction results of cylinder is about 1.0 °C.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Aiming at the problem that the unknown variation rule of molten pool and the interlayer effect on the forming efficiency and precision of products in the process of selective laser melting(SLM) of ...high-strength aluminum alloy A17075, the influence of different process parameters (laser power and scanning speed) on the morphology of the molten pool and the temperature field of the various forming layers was investigated. The finite element analysis software ANSYS was used to establish a multi-layer and multi-channel temperature field finite element model for SLM forming of thin-walled metal parts, and at the same time, the loading of the laser heat source, the laser power and the scanning speed were simulated by using the programming of the language APDL (ansys parametric design language), and the "element birth and death" technique was adopted to describe the dynamic growth process of the metal powder material and the distribution of the transient temperature field was derived. The results show that the laser
The molten pool images of GMAW (Gas Metal-Arc Welding) was acquired during the base time period using a self-built system for measuring the transient temperature field of molten pool. The transient ...temperature field of the molten pool of GMAW at different welding speeds was calculated based on the principle of colorimetric temperature measurement. When analyzing the temperature distribution at the middle and tail region of the molten pool in the process of hump bead formation under high speed GMAW, it was found that the temperature distribution of the molten pool is uneven perpendicular to the welding direction, and this law does not accord with the time when the hump appears in the image, and the accuracy rate accorded with the law was also counted. Through this rule, the welding robot can adjust and control the process in time before the appearance of hump, and the prediction of hump before bead formation under GMAW is preliminarily realized.
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Accurate cement slurry temperature prediction is a prerequisite for improving cementing quality and ensuring wellbore integrity and sealing of oil and gas wells. It plays a crucial role in preventing ...“gas migration” and “sustained casing pressure” problems and reducing environmental pollution. The construction links before the start of cementing are neglected by the existing prediction methods, and thus, it is not reasonable to assume initial temperature conditions. In this paper, a two-dimensional transient temperature field model for cementing is developed and its reasonableness is verified. The distribution of wellbore and formation temperature fields at cementing beginning is calculated. In addition, the influence rules of several factors on the cement slurry circulation temperature are calculated and discussed. The results show that the initial temperature varies significantly and that each factor affects the fluid circulation temperature in different ways and to different degrees. If the circulating wash operation before cementing is considered, the temperature field decreases in the downhole section and increases in the uphole section compared to the assumption that the initial condition is the original formation temperature. By correcting the initial conditions, the accuracy of cement slurry circulation temperature prediction can be improved.
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FEA-based Gaussian density heat source models were developed to study the effect of convective and radiative heat sinks on the transient temperature field predicted by the available analytical ...solution of the purely conduction-based Goldak’s heat source. A new complex 3D Gaussian heat source model, incorporating all three modes of heat transfer, i.e. conduction, convection and radiation, has been developed as an extension of the Goldak heat source. The approximate transient analytical solutions for this 3D moving heat source were derived and numerically benchmarked with the available measured temperature and weld pool geometry data. The calibrated transient temperature field generated by MATLAB programming was 5 to 6 times faster than by FEA-based simulation. The new complex 3D Gaussian heat source model and its approximate solution could significantly reduce the computing time in generating the transient temperature field and be an efficient alternative to extensive FEA-based simulations of heating sequences, where virtual optimisation of a melting heat source (i.e. used in welding, heating, cutting or other advanced manufacturing processes) is desirable for characterisation of material behaviour in microstructure evolution, melted pool, microhardness, residual stress and distortions.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
This paper proposes a simplified lumped parameter thermal network (LPTN) model for thermal analysis under the inter-turn short-circuit (SC) faults of a five-phase fault-tolerant permanent magnet (PM) ...motor for electric vehicles. The proposed model can consider circumferential heat transfer, variable copper loss, and uneven loss distribution. Firstly, an analytical calculation formula of inter-turn SC current is proposed to separate the copper loss of SC turns from electromagnetic simulation, and the accuracy of the formula is verified by finite element analysis (FEA). Secondly, a simplified LPTN model is proposed, the calculation formulas of the thermal resistance are given, and the simplified principle is explained. By comparing the results of different simplifications, it is found that the error between the simplified model and the original model is small. Finally, the proposed model is verified by experiments. The results show that the simplified model can achieve not only a high calculation speed but also a high accuracy. Moreover, the proposed model is applicable to all cases of asymmetrical temperature distribution.
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The numerical manifold method (NMM), combined with the precise time integration method (PTIM), is proposed for thermal shock fracture analysis. The temperature and displacement discontinuity across ...crack faces is naturally portrayed attributing to the cover systems in the NMM. The crack tip singularities are characterized through the use of asymptotic bases in the approximations. The discrete equations for transient thermal analysis are firstly solved with the PTIM and then the thermoelastic study is performed. With the interaction integral, the stress intensity factors are computed. Several examples are tested and the nice consistency between the present and existing results is found.
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An analytical model has been developed for calculating three-dimensional transient temperature fields arising in the direct deposition process to study the thermal behavior of multi-track walls with ...various configurations. The model allows the calculation of all characteristics of the temperature fields (thermal cycles, cooling rates, temperature gradients) in the wall during the direct deposition process at any time. The solution of the non-stationary heat conduction equation for a moving heat source is used to determine the temperature field in the deposited wall, taking into account heat transfer to the environment. The method considers the size of the wall and the substrate, the change in power from layer to layer, the change in the cladding speed, the interpass dwell time (pause time), and the heat source trajectory. Experiments on the deposition of multi-track block samples are carried out, as a result of which the values of the temperatures are obtained at fixed points. The proposed model makes it possible to reproduce temperature fields at various values of the technological process parameters. It is confirmed by comparisons with experimental thermocouple data. The relative difference in the interlayer temperature does not exceed 15%.
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This paper investigates the nonlinear transient thermal responses of functionally graded beams resting on tensionless foundation under unsteady heat conduction. The interaction between functionally ...graded beams and tensionless foundation is only compressive without tensile reaction. The whole model is established based on Euler beam theory and solved by the combination of differential quadrature method (DQM), Newmark method and Newton–Raphson method. Some detailed numerical results are carried out to reveal the transient heat conduction procedure and the mechanical behaviors of functionally graded beam resting on tensionless foundation.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
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