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991.
Aluminum casting alloys exhibit creep behavior when the materials are exposed to high temperature and load. In this article,
the stress- and temperature-dependent creep behavior of a die casting A380-T5 aluminum alloy was simulated using a classical
constitutive model. The bolt-load retention behavior of the material was analyzed in a head bolt joint in an aluminum engine
under thermal cycle condition using the finite element method. In this simulation, transient thermal analysis was performed
first to calculate the metal temperature at the head bolt joint as a function of time during engine thermal cycling. This
temperature was then input as the thermal loading in the subsequent structural analysis to calculate its effect on the bolt-load
retention. The finite element analysis (FEA) model for the bolt-load retention simulation includes not only the plasticity
in all metal components but also the creep properties of head bolt threads in the cast aluminum engine block. The FEA model
was validated by good correlation between the predicted head bolt-load loss and the experimental measurement during engine
thermal cycling. The simulation results also indicated that creep in the head bolt threads of cast aluminum engine block was
mainly responsible for the load loss in the head bolt joint.
This article is based on a presentation given in the symposium entitled “Simulation of Aluminum Shape Casting Processing:
From Design to Mechanical Properties” which occurred March 12–16, 2006 during the TMS Annual Meeting in San Antonio, Texas
under the auspices of the Computational Materials Science and Engineering Committee, the Process Modeling, Analysis and Control
Committee, the Solidification Committee, the Mechanical Behavior of Materials Committee, and the Light Metal Division/Aluminum
Committee. 相似文献
992.
A series of nanocomposite thin films, composed of Nd2Fe14B and α-Fe, has been prepared by DC-magnetron sputtering combined ion beam sputtering onto Si (100) substrates. The effects of post annealing on the microstructure and magnetic properties of [NdFeB/α-Fe/NdFeB]-type thin films have been investigated. The X-ray diffraction (XRD) study showed that annealing of the films for 30min at temperatures 550,600,650,700℃ resulted in the appearance of diffraction peaks, characteristic for Nd2Fe14B tetragonal structure, α-Fe and Nd2O3 phases. The investigation using the Vibrating Sample Magnetometer (VSM) with a maximum applied field of 2 T indicated that with the increase of the annealing temperature, the magnetic properties of the multilayer films were improved and reached peak value at 650℃ (Hci=41.72kA·m-1, Mr/Ms=0.4, (BH)max=30.35kJ·m-3), after which the magnetic properties were decreased greatly. Along with the increase of the thickness of α-Fe layer from Tα-Fe16nm, the coercivity Hci, saturation magnetization Ms, and remanence ratio Mr/Ms all declined. As the Atomic Force Microscope (AFM) indicated, after being annealed at 650℃ for 30min, the sample was showed fine surface morphology with grain size 60nm≤dα-Fe≤80nm and 100nm≤dNdFeB≤150nm. 相似文献
993.
Due to their simplicity and intuitiveness, swept surfaces are widely used in many surface modelling applications. In this paper, we present a versatile swept surface technique called the boundary constrained swept surfaces. The most distinct feature is its ability to satisfy boundary constraints, including the shape and tangent conditions at the boundaries of a swept surface. This permits significantly varying surfaces to be both modelled and smoothly assembled, leading to the construction of complex objects. The representation, similar to an ordinary swept surface, is analytical in nature and thus it is light in storage cost and numerically very stable to compute. We also introduce a number of useful shape manipulation tools, such as sculpting forces, to deform a surface both locally and globally. In addition to being a complementary method to the mainstream surface modelling and deformation techniques, we have found it very effective in automatically rebuilding existing complex models. Model reconstruction is arguably one of the most laborious and expensive tasks in modelling complex animated characters. We demonstrate how our technique can be used to automate this process. 相似文献
994.
不停车清洗预膜在2号高炉净循环水系统的应用 总被引:1,自引:0,他引:1
循环冷却水系统长期运行过程中,由于多种因素影响,管道、阀门、水泵等设备产生结垢和腐蚀,为使水系统保持长期正常运行,减缓腐蚀结垢速度,需投加杀菌剂和阻垢缓蚀剂,2a进行一次清洗和预膜。主要介绍了2号高炉净循环水系统不停车清洗预膜的步骤、效果,并推荐在工况相似循环水系统中参考应用。 相似文献
995.
996.
997.
新型氮系阻燃剂——三嗪衍生物的合成 总被引:6,自引:0,他引:6
合成了两种三嗪衍生物,并将其与多聚磷酸铵复配用于聚丙烯阻燃试验,结果表明,这两种阻燃剂具有良好的阻燃作用。 相似文献
998.
首先建立缺陷空间分布和粒径分布的模型,并讨论了缺陷通过版图产生电路错误的过程,给出了IC功能成品率模拟器XD-YES的实现。用XD-YES对微电子测试图和实际IC的功能成品率模拟和分析表明,其结果与实际符合很好,从而表明XD-YES的可行性和实用性。 相似文献
999.
1000.