A new generalized upper-bound solution for the ECAE process
A new generalized upper-bound solution for the ECAE process
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DOI：
10.1007/s00170-009-2103-y
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发表时间：
2010
期刊：
影响因子：
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通讯作者：
K. Abrinia;M. J. Mirnia
中科院分区：
文献类型：
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作者：
K. Abrinia;M. J. Mirnia
本文提出了一种新的等通道角挤压（ECAE）过程的广义上限解。使用贝塞尔曲线的数学定义，制定流线来定义广义变形区域。基于该变形区域，获得运动学上允许的速度场，从中计算上限解。通过改变定义贝塞尔形状流线的参数（进而定义变形区域），对上限解进行了优化。考虑通过 90° 弯曲的等通道角挤压。使用此处提出的公式，可以预测死金属区的形状及其随摩擦条件的变化。与之前的工作不同，之前的工作中为死金属区域假设了固定的圆形形状，在本文中，使用了广义形状的贝塞尔曲线。获得了 ECAE 挤出压力的最佳值，并将其与先前工作的实验和理论数据进行了比较。结论是，当前的解决方案比以前的所有工作都有改进，并且作者的结果更接近实验数据。
A new generalized upper-bound solution for the equal-channel angular extrusion (ECAE) process is presented in this paper. Using mathematical definition of Bezier curves, a streamline was formulated to define a generalized deforming region. Based on this deforming region, a kinematically admissible velocity field was obtained from which upper-bound solutions were computed. By changing the parameters defining the Bezier-shaped streamline which in turn defines the deforming region, the optimization of the upper-bound solution was carried out. Equal-channel angular extrusion through a 90° bend was considered. Using the formulation presented in here, it was possible to predict the shape of the dead metal zone and its variation with frictional conditions. Unlike previous work in which a fixed circular shape had been assumed for the dead metal zone, in this paper, a generalized shaped Bezier curve was used. The optimum value of the extrusion pressure for ECAE was obtained and compared with both experimental and theoretical data from previous works. It was concluded that the present solution gave an improvement over all previous works and the authors’ results were closer to experimental data.