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Numerical analysis of projection welding on auto-body sheet metal using a coupled finite element method 总被引:1,自引:1,他引:0
W.-F. Zhu Z.-Q. Lin X.-M. Lai A.-H. Luo 《The International Journal of Advanced Manufacturing Technology》2006,28(1-2):45-52
A comprehensive finite element method employing a subroutine to link up submodules of commercial code ANSYS is proposed to
perform analysis of projection welding in quantitative detail. In order to solve the complexity due to dynamic changes in
heat and electrical current flow paths, as well as temperature-dependent material properties, information about contact interfaces
and the geometry of the projection areas have been taken into account. By updating parameter information among these submodules
in an incremental manner, a truly thermal-electrical-mechanical coupled numerical analysis is realized for projection welding
simulation. A case study of an automotive door assembly welding process is carried out and a series of experiments is conducted
to confirm the validity of the newly developed method. The agreement between the experimental and numerical results is satisfactory,
indicating that the incrementally coupled finite element method may be suitable for projection welding research. Finally,
future work to extend this method in optimizing projection welding process design is also presented. 相似文献
997.
介绍了河南内乡硅线石浮选工艺、除铁效果及精矿主要理化指标 ,指出对浮选精矿采用磁选进一步除铁 ,效果比酸浸要好。 相似文献
998.
Mingfang Lai Jing Li Jun Yang Jingjiang Liu Xin Tong Huiming Cheng 《Polymer International》2004,53(10):1479-1484
Nanocomposites based on poly(hydroxybutyrate‐co‐hydroxyvalerate) (PHBV) and multi‐walled carbon nanotubes (MWNTs) were prepared by solution processing. Ultrasonic energy was used to uniformly disperse MWNTs in solutions and to incorporate them into composites. Microscopic observation reveals that polymer‐coated MWNTs dispersed homogenously in the PHBV matrix. The thermal properties and the crystallization behavior of the composites were characterized by thermogravimetric analysis, differential scanning calorimetry and wide‐angle X‐ray diffraction, the nucleant effect of MWNTs on the crystallization of PHBV was confirmed, and carbon nanotubes were found to enhanced the thermal stability of PHBV in nitrogen. Copyright © 2004 Society of Chemical Industry 相似文献
999.
WE Carson TA Fehniger S Haldar K Eckhert MJ Lindemann CF Lai CM Croce H Baumann MA Caligiuri 《Canadian Metallurgical Quarterly》1997,99(5):937-943
Resting lymphocyte survival is dependent upon the expression of Bcl-2, yet the factors responsible for maintaining lymphocyte Bcl-2 protein expression in vivo are largely unknown. Natural killer (NK) cells are bone marrow-derived lymphocytes that constitutively express the beta and common gamma(c) subunits of the IL-2 receptor (R) as a heterodimer with intermediate affinity for IL-2. IL-15 also binds to IL-2Rbeta gamma(c) and is much more abundant in normal tissues than IL-2. Mice that lack the IL-2 gene have NK cells, whereas mice and humans that lack IL-2R gamma(c) do not have NK cells. Further, treatment of mice with an antibody directed against IL-2Rbeta results in a loss of the NK cell compartment. These data suggest that a cytokine other than IL-2, which binds to IL-2Rbeta gamma(c), is important for NK cell development and survival in vivo. In the current report, we show that the recently described IL-15R(alpha) subunit cooperates with IL-2Rbeta gamma(c) to transduce an intracellular signal at picomolar concentrations of IL-15. We demonstrate that resting human NK cells express IL-15R(alpha) mRNA and further, that picomolar amounts of IL-15 can sustain NK cell survival for up to 8 d in the absence of serum. NK cell survival was not sustained by other monocyte-derived factors (i.e., TNF-alpha, IL-1beta, IL-10, IL-12) nor by cytokines known to use gamma(c) for signaling (i.e., IL-4, IL-7, IL-9, IL- 13). One mechanism by which IL-15 promotes NK cell survival may involve the maintenance of Bcl-2 protein expression. Considering these functional properties of IL-15 and the fact that it is produced by bone marrow stromal cells and activated monocytes, we propose that IL-15 may function as an NK cell survival factor in vivo. 相似文献
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