共查询到18条相似文献,搜索用时 140 毫秒
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与基于网格离散的数值计算方法相比,无网格方法利用离散节点代替网格单元,回避了拓扑结构复杂、单元编号和信息传递等问题,在模拟分析相变界面移动、大变形、裂纹动态扩展等方面展现出极大的适用性。依据移动最小二乘法构造了场量近似函数,针对连铸板坯在结晶器初始凝固过程中的传热特征,构造和推导了基于无网格伽辽金法的板坯传热和凝固行为控制方程,结合采用伽辽金积分弱形式和变分原理,建立了铸坯热弹塑性二维横截面数值计算模型,以连铸生产现场实测铜板温度反算的结晶器热流为边界条件,模拟和分析了结晶器内初生坯壳的非均匀传热、应力和应变。研究结果表明,板坯在结晶器内宽度方向的传热和力学行为呈现出显著的非均匀特征,在距离弯月面200 mm范围内是应力应变快速增长阶段,之后应力应变增长速度放缓,距弯月面550 mm处,铸坯等效应力和应变出现极大值,分别为15.97 MPa和0.76%;在宽度方向上,角部受二维散热的影响,温度下降较快,出现应力集中现象,相邻的偏角部存在应力应变低谷,与角部在温度、应力、应变方面存在较大差异。上述结果验证了无网格方法计算铸坯非均匀传热、力学行为的可行性和适用性,为无网格方法应用至铸坯裂纹萌生与扩展的研究提供基础和参考。 相似文献
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针对连铸小方坯的中心疏松等质量缺陷,建立了凝固传热数学模型,以研究二冷强度对连铸小方坯凝固过程的影响规律,优化二冷制度,改善铸坯质量.本文基于射钉和测温实验所建立的小方坯凝固传热模型精细度较高,用此模型深入研究二冷喷嘴的数量和喷射范围对小方坯凝固传热的影响;经验证,模拟结果与实测结果误差在1.7%以内.利用该模型定量分析了二冷强度对铸坯温度,凝固坯壳厚度和凝固终点的影响规律.结果表明,随着二冷强度的增大,二冷区内的铸坯表面中心温度降低,而进入空冷区后则逐渐趋于一致.二冷强度每增加10%,足辊段出口处温度平均降低8℃,二冷一段出口处温度平均降低10.75℃,二冷二段出口处温度平均降低10.75℃,二冷三段出口处温度平均降低9.75℃,铸坯凝固终点缩短约0.168 m. 相似文献
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本文针对连铸坯的凝固传热特点,通过对传热方式和定解条件的适当简化和对有限差分格式的改进,建立了连铸圆形坯、小方坯的传热数学模型及其适用于微型机小内存特点的快速数值计算方法。该方法便于现场技术人员用来求算铸坯的温度场分布,也可做为工艺自动控制模型的基础。 相似文献
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对现有连铸二冷区喷嘴布置进行分析,根据布置优化原则提出采用喷嘴水流密度数值叠加的方法,在拉坯方向和铸坯横断面方向上对喷嘴布置方式进行优化.其中,在铸坯横断面方向上,考虑了横向水流密度分布的不均匀性对铸坯凝固过程的影响,建立二维铸坯传热数学模型,仿真得到不同位置的铸坯断面凝固形貌,并比较了优化前后铸坯温度分布、凝固情况和铸坯质量.结果表明喷嘴布置方式优化后,二冷区铸坯在拉坯方向和断面方向上喷淋水区域内均匀冷却,周期性温度回升变小,表面温度能够均匀下降,保证了较好的铸坯内部质量. 相似文献
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建立了结晶器内连铸坯凝固传热的有限元数值计算模型,并就模型中两种凝固潜热处理方法,两种三点时间格式以及两种热容矩阵的应用进行了比较,同时研究了时间步长和计算网格大小对数值模拟结果的影响。 相似文献
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钢的软接触电磁连铸技术的研究进展 总被引:1,自引:0,他引:1
钢的软接触电磁连铸技术(SoftContactElectromagneticContinuousCasting)是利用高频交变电磁场在结晶器内铸坯初始凝固区施加电磁压力来减少钢液与结晶器壁的接触压力,从而减小结晶器振动对铸坯表面质量的影响,降低拉坯阻力和减弱初始凝固点的传热来提高铸坯表面质量。分析了实现钢的软接触电磁连铸在结晶器结构、材质以及电磁场参数等方面需要解决的问题,并介绍了该技术的最新研究成果:高频调幅磁场及无结晶器振动的电磁连铸技术。 相似文献
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《钢铁冶炼》2013,40(2):149-156
AbstractHeat transfer between mould and strand has a critical influence on billet quality, caster productivity and operating safety. It is very important to obtain the correct distributions of temperature and heat flux, and many studies are made on the calculation methods of heat transfer between strand and mould, aiming to reduce the computation time and improve the calculation accuracy. In the present paper, based on measured data of temperature and heat flux during round billet continuous casting, the calculation method which combines the online measurement data and numerical simulation was investigated. Through identifying the local thermal resistance and its distribution between the mould and the strand by an inverse heat transfer model, the heat flux and shell thickness profiles were calculated. To avoid the iterative solution by inverse model, a faster alternative model using an artificial neural network was developed to predict the thermal resistance from the measured temperature. After training, there is an exact correspondence between the observed temperature values and the thermal resistance. The calculation results obtained by the combination of neural network and numerical simulation can correctly reflect the characteristics of non-uniform heat transfer around the mould circumference, which provides a worthwhile and applicable method for online calculation and visual technology of heat transfer and solidification in continuous casting mould. 相似文献
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钢厂1#连铸机以0.95 m/min拉速生产SS400,D36和X70钢150~180 mm连铸板坯时,易产生角部纵裂纹,发生率最高可达5%。利用商业有限元软件ANSYS,建立了板坯连铸结晶器二维切片式凝固传热数学模型,并采用传热和应力/应变直接耦合的方法对连铸过程结晶器内凝固传热进行计算,分析了各钢种在0.95~1.05m/min拉速下铸坯温度分布以及温度分布不均引起的热应力。工业试验结果表明,根据优化计算结果,将板坯结晶器窄面的锥度系数由原来的1.00%改进为1.10%后,有效地消除了1#连铸机板坯的角部纵裂纹。 相似文献
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Aiming at the process of electromagnetic continuous casting (EMCC), a three dimensional finite element model on electromagnetic field and temperature field was developed through the commercial software ANSYS to investigate the effects of induction heat of high frequency electromagnetic field on the early solidification process of molten steel in soft contact mold under various conditions of exciting current parameters. The results show that the induction heat has significant effects on the early solidification process, which appear as increasing the billet surface temperature, thinning the initial solidified shell and lowering the starting point of the initial solidification. The increases of exciting current frequency and density make the effects of induction heat on solidification process increased remarkably. Especially, with the increase of exciting current frequency, the early solidification process and shell growth become non-uniform in billet circumferential direction. Morever, if the exciting current density exceeds a certain value, there occurs a high temperature region in the top of molten steel column, and then the initial solidification rate is decreased greatly. 相似文献