排序方式: 共有48条查询结果,搜索用时 31 毫秒
1.
Rodrigues Christian M. G. Ludwig Andreas Wu Menghuai Kharicha Abdellah Vakhrushev Alexander 《Metallurgical and Materials Transactions B》2019,50(3):1334-1350
Metallurgical and Materials Transactions B - A two-phase Eulerian–Eulerian volume-averaged model is used to predict the formation of macrosegregation during the twin-roll casting of... 相似文献
2.
A three-phase model for mixed columnar-equiaxed solidification 总被引:1,自引:0,他引:1
A three-phase model for mixed columnar-equiaxed solidification is presented in this article. The three phases are the parent
melt as the primary phase, as well as the solidifying columnar dendrites and globular equiaxed grains as two different secondary
phases. With an Eulerian approach, the three phases are considered as spatially coupled and interpenetrating continua. The
conservation equations of mass, momentum, species, and enthalpy are solved for all three phases. An additional conservation
equation for the number density of the equiaxed grains is defined and solved. Nucleation of the equiaxed grains, diffusion-controlled
growth of both columnar and equiaxed phases, interphase exchanges, and interactions such as mass transfer during solidification,
drag force, solute partitioning at the liquid/solid interface, and release of latent heat are taken into account. Binary steel
ingots (Fe-0.34 wt pct C) with two-dimensional (2-D) axis symmetrical and three-dimensional (3-D) geometries as a benchmark
were simulated. It is demonstrated that the model can be used to simulate the mixed columnar-equiaxed solidification, including
melt convection and grain sedimentation, macrosegregation, columnar-to-equiaxed-transition (CET), and macrostructure distribution.
The model was evaluated by comparing it to classical analytical models based on limited one-dimensional (1-D) cases. Satisfactory
results were obtained. It is also shown that in order to apply this model for industrial castings, further improvements are
still necessary concerning some details. 相似文献
3.
4.
5.
Christian Rodrigues Andreas Ludwig Abdellah Kharicha Menghuai Wu 《Transactions of the Indian Institute of Metals》2018,71(11):2645-2649
During twin-roll casting, an alloy melt is passing the gap between two counter-rotating rolls, where cooling and solidification leads to the continuous formation of a solid strand. In order to describe this process, a two-phase Eulerian–Eulerian volume-averaging model is presented that accounts for (1) transport and growth of spherical grains within a flowing melt, (2) the formation of a coherent solid network above a specific solid fraction and (3) the viscoplastic flow of the solid network with the interstitial melt during casting and compression. For the considered case of an inoculated Al–4wt%Cu alloy, the process conditions are chosen such that two relatively thick viscoplastic semi-solid shells meet between the rolls, and thus, the material is pressed together and squeezed against the casting direction. The squeezed out material consists of segregated melt and some solid that quickly disappears after melting. It is observed during this study that macrosegregation distributions are inherently connected to the mush deformation that is enforced during the hot rolling process. 相似文献
6.
Virtual manufacturing based on through-process modelling becomes an evolving research area which aims at integrating diverse simulation tools to realize computer-aided design, analysis, prototyping and manufacturing. Numerical prediction of the as-cast microstructure is an initial and critical step in the whole through-process modelling chain for engineering components. A commercial software package with the capability of calculating important microstructure features for aluminium alloys is used to simulate a G-AlSi7MgCu0.5 laboratory casting. The simulated microstructure, namely grain size, secondary dendrite arm spacing and diverse phase fractions are verified experimentally. Correspondence and discrepancies are reported and discussed. 相似文献
7.
Menghuai Wu Andreas Ludwig Andreas Bührig-Polaczek Martin Fehlbier Peter R. Sahm 《International Journal of Heat and Mass Transfer》2003,46(15):2819-2832
A two-phase volume averaging model was used to study convection and grain movement, and their influence on the globular equiaxed solidification. Both liquid and solid phases were treated as separate interpenetrating continua. The mass, momentum, species and enthalpy conservation equations for each phase and a grain transport equation were coupled. An ingot casting (Al-4 wt.% Cu) with near globular solidification morphology was simulated. Case studies with different modeling assumptions such as with and without grain movement, and with slip and non-slip boundary conditions for solid phase were presented and compared. Understanding of grain evolution and macrosegregation formation in globular equiaxed solidification was improved. 相似文献
8.
9.
冷贮备系统可靠性指标的多层Bayes估计 总被引:3,自引:0,他引:3
白成刚 《浙江大学学报(工学版)》1998,32(3):325-329
本文利用Baeyes及多层Bayes方法对冷贮备系统的可靠性指标失效率,可靠度及平均寿命等进行了分析,最后。运用随机模扬方法,对所得到的结果进行了分析比较。 相似文献
10.
建立刺梨中15种有机氯农药残留的气相色谱-三重四级杆串联质谱(GC-MS/MS)检测法。刺梨样品采用QuEChERS前处理,正己烷溶液进行提取,经乙二胺-N-丙基硅烷(PSA)和C18各50 mg固相分散净化,浓缩定容后用GC-MS/MS法在多反应监测(MRM)模式下进行测定,通过保留时间、特征离子及其相对丰度定性,外标法定量。15种有机氯农药在0.05~1.00 μg/mL质量浓度范围内呈良好的线性关系,相关系数R2均>0.997。分别向刺梨样品中分别加入标准品25 μg/kg、50 μg/kg、100 μg/kg时,加标平均回收率在81.98%~105.55%之间,相对标准偏差(n=6)均<10%,检出限(S/N=3)在0.001 2~0.021 2 mg/kg。该方法具有经济、快速、灵敏度高、重现性好等优势,适用于食品中多种农药残留的同时快速测定。 相似文献