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С.В.Летров 《铁道机车车辆工人》2002,(8):28-30
70年代,前苏联从匈牙利购买了大量机车柴油机.到80年代中期,这些机车柴油机再也不能使用了.其主要原因是柴油机中较为昂贵的零部件--曲轴被磨损了. 相似文献
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The miniaturization of products requires the mass production of microparts. The microforming can well meet this requirement. Due to the emergence of decreasing flow stress scale effect in the micro scale, the traditional forming process and theory may fail. Based on the crystal plasticity theory, upsetting tests of micro copper cylinders with different dimensions and grain sizes were simulated, and the decreasing flow stress scale effect was studied and discussed. Results show that with the decrease of billet dimensions, the flow stress is gradually decreased, and the decreasing flow stress scale effect is emerged; with the increase of grain size, the decreasing flow stress scale effect is more remarkable. It can also be seen that the decreasing flow stress scale effect can be well simulated with the crystal plasticity theory, and the necessary relevant information is provided for deeper understanding on this scale effect, as well as the design of processes and die structures in the microforming. 相似文献
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��������㣬��������������ϣ�� 《交通运输系统工程与信息》2013,13(6):154-160
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����飬Ԭ���ޣ����������־������˼�� 《交通运输系统工程与信息》2016,16(3):141-147
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