U.S-Czech Research on Computational Models in Phenomenological Plasticity, Planning Visit

通过这次计划访问，美国研究人员北方亚利桑那大学的Heidi Feigenbaum和加利福尼亚大学戴维斯分校的Yannis Dafalias将与捷克合作伙伴启动一个国际合作研究项目，以研究计算现象学可塑性。 他们的同行Jiri Plesek将领导捷克科学院热机械研究所的合作工作。 计划中的长期合作的结果应该会提高我们对材料力学的基本理解，如果成功的话，可能会导致新的模型，以改善对实际工程和材料问题的预测，从预测棘轮应变到金属成形过程中的弹性回弹。美国团队在变形和塑性理论以及定向变形和模拟方面的优势，在计算和理论方面对捷克伙伴的补充。 具体来说，Plesek的小组将贡献有限元平台，Feigenbaum-Dafalias模型将被实施。他们的目标是通过使用实验结果和分析解来检查变形的基本模式，如拉伸试验和棘轮效应，从而改进计算模型常数的计划。 为了更好地校准，他们打算在大变形有限元计算机代码的框架内实现控制方程。 这次项目规划访问实现了通过使美国和欧洲的研究人员能够在共同感兴趣和能力的领域分享资源和专业知识来提高我们对材料力学知识的计划目标。 这个美国-捷克团队打算建立一个简单、准确的金属塑性模型，解决定向畸变硬化问题。 更广泛的影响可能包括最终能够避免在整个寿命期内受到循环塑性载荷的结构发生故障。 长期的成功可能意味着未来成本和时间的节省，以及通过改进工程应用提高安全性。

Through this planning visit U.S. researchers Heidi Feigenbaum of Northern Arizona University and Yannis Dafalias, from the University of California-Davis, will initiate an international cooperative research project with Czech partners to examine computational phenomenological plasticity. Their counterpart, Jiri Plesek, will head collaborative efforts at the Czech Academy of Sciences' Institute of Thermomechanics. Results from the planned long-term collaboration should improve our fundamental understanding of the mechanics of materials and, if successful, may lead to new models to improve predictions for practical engineering and materials problems, ranging from predicting ratcheting strains to elastic spring back during metal forming.The U.S. team's strengths in deformation and plasticity theory as well as directional distortion and simulation offer an excellent complement to those of the Czech partners in computation and theory. Specifically, Plesek's group will contribute the finite element platform with which the Feigenbaum-Dafalias models will be implemented. Together their goal is to refine plans for calculating model constants by using experimental results and analytical solutions to examine the fundamental modes of deformation, such as tensile tests and ratcheting. For better calibration, they intend to work toward implementing governing equations in the framework of a large deformation finite element computer code. This project planning visit fulfills the program objective of advancing our knowledge of the mechanics of materials by enabling researchers in the United States and Europe to share resources and expertise in areas of mutual interest and competence. This U.S.-Czech team intends to produce a simple, accurate metal plasticity model that addresses directional distortional hardening. Broader impacts may include the eventual ability to avoid failures in structures that are subject to cyclic plastic loading throughout their life-spans. Long-term success could mean future savings in cost and time, coupled with heightened safety through improved engineering applications.