Modeling and Characterization of Materials for Dynamic Metal Working Processes

轧制、锻造和挤压等制造操作是 其特征在于间断的、非等温的、大变形 在高应变速率（104 sec-1）和高同源温度下 (0.5 0.9）。 可供验证的测试数据非常少 和/或细化本构关系，所述本构关系被提出来描述 在这些载荷条件下的材料性能。 的目的 本研究对Fe-2%Si和Ti6 Al-4V进行了实验研究 在分离式Hopkinson扭杆中， 同系温度的各种值。 这些测试数据和 其他文献中可用的将被用来界定 本构关系的函数形式，并找到价值 材料参数。 这些预测能力 本构方程将通过比较 分析/计算结果与实验结果下 加载条件不同于用于建立它们的加载条件， 包括准静态预应变试样的动态加载 在不同于动态加载的方向上。 的 发展的本构关系将用于分析挤压 和热锻工艺，以及加载速率和 初始试样温度时的起始和增长 锻造、扭转和复合载荷中的剪切带。 研究 将联合收割机结合彻底的理论/数值研究， 准确的实验研究。 的密切合作 实验和理论工作的结合 应该有助于制定可靠的本构关系， 用于分析其他高应变率过程，如机械加工 以及快速运动的侵彻体对金属目标的侵彻。

Manufacturing operations like rolling, forging, and extrusion are characterized by interrupted, non-isothermal, large deformations at high strain rates (104sec-1) and high homologous temperatures (0.5 to 0.9). There is very little test data available to validate and/or refine constitutive relations proposed to describe the material behavior under these loading conditions. The purpose of this research is to perform experiments on Fe-2% Si and Ti6A1-4V in a split Hopkinson torsion bar at different strain-rates and various values of the homologous temperature. These test data and others available in the literature will be used to delimit the functional forms of constitutive relations, and also to find values of material parameters. The predictive capability of these constitutive equations will be ascertained by comparing analytical/computed results with experimental findings under loading conditions different from those used to establish them, including dynamic loading of specimens pre-strained quasistatically in a direction different from that of dynamic loading. The developed constitutive relations will be used to analyze extrusion and hot forging processes, and the effect of loading rate and initial specimen temperature upon the initiation and growth of shear bands in forging, torsion, and combined loading. The study will combine a thorough theoretical/numerical effort with careful and accurate experimental investigation. The close collaboration and integration between the experimental and theoretical work should help formulate reliable constitutive relations that can be used to analyze other high strain-rate processes such as machining and penetration of metallic targets by fast moving penetrators.