Dual-Phase Steels - From Micro to Macro Properties (EXASTEEL-2)

在EXASTEEL-2项目中，可扩展迭代求解器、材料科学计算建模、性能工程和并行直接求解器方面的专家正在联手开发新的计算算法，并为计算材料科学中的重大挑战问题实现软件。对复杂新材料宏观行为的预测模拟的需求日益增加。在EXASTEEL-2项目中，考虑了现代微非均相（双相）钢的这一问题，试图从微观水平上预测新材料的宏观性能。它的目标是开发算法和软件的虚拟实验室预测材料测试在硅。一个瓶颈是描述新材料所需的多尺度模型的计算复杂性，包括在晶体尺度上足够精确的微机械驱动模型。因此，新的超可扩展非线性隐式求解器将被开发出来，并与高度并行的计算尺度桥接方法（FE^2）相结合，与后续的和永久的性能工程交织在一起，将虚拟实验室的材料测试和设计的具有挑战性的工程应用带到极限尺度计算。我们设想从描述性到预测性宏观模拟的不断增加的过渡，并考虑到，据我们所知，首次在计算尺度桥接方法中，双相钢的多晶性质，包括微观尺度上的晶界效应。如果没有EXASTEEL-1的算法和软件基础设施，我们的目标就无法实现。我们将完成从EXASTEEL-1项目开始的范式转换，从牛顿-克雷洛夫解算器到非线性方法（及其组成），并提高并发性和减少通信。通过将非线性域分解与多网格方法相结合，我们计划利用非线性方法的两种隐式求解方法的可扩展性。虽然我们的应用程序是特定的，但算法和优化软件的影响将远远超出特定的应用程序。非线性隐式求解器是许多仿真代码的核心，我们的软件构建块PETSc、BoomerAMG、PARDISO和FEAP都是具有大量用户基础的软件包。这些软件包的进步是在这个项目的工作包中明确规划的。因此，该项目涉及计算算法（非线性隐式求解器和规模桥接）、应用软件和编程（PE、混合编程、加速器）。

In the EXASTEEL-2 project, experts on scalable iterative solvers, computational modeling in materials science, performance engineering, and parallel direct solvers are joining forces to develop new computational algorithms and implement software for a grand challenge problem from computational materials science. There is an increasing need for predictive simulations of the macroscopic behavior of complex new materials. In the EXASTEEL-2 project, this problem is considered for modern micro-heterogeneous (dual-phase) steels, attempting to predict the macroscopic properties of new materials from those on the microscopic level. It is the goal to develop algorithms and software towards a virtual laboratory for predictive material testing in silico. A bottleneck is the computational complexity of the multiscale models needed to describe the new materials, involving sufficiently accurate micromechanically motivated models on the crystalline scale. Therefore, new ultra-scalable nonlinear implicit solvers will be developed and combined with a highly parallel computational scale bridging approach (FE^2), intertwined with a consequent and permanent performance engineering, to bring the challenging engineering application of a virtual laboratory for material testing and design to extreme scale computing. We envisage a continuously increased transition from descriptive to predictive macroscopic simulations and take into account, to the best of our knowledge for the first time within a computational scale bridging approach, the polycrystalline nature of dual phase steels including grain boundary effects at the microscale.Our goals could not be reached without building on the algorithm and software infrastructure from EXASTEEL-1. We will complete the paradigm shift, begun in the EXASTEEL-1 project, from Newton-Krylov solvers to nonlinear methods (and their composition) with improved concurrency and reduced communication. By combining nonlinear domain decomposition with multigrid methods we plan to leverage the scalability of both implicit solver approaches for nonlinear methods.Although our application is specific, the algorithms and optimized software will have an impact well beyond the particular application. Nonlinear implicit solvers are at the heart of many simulation codes, and our software building blocks PETSc, BoomerAMG, PARDISO, and FEAP are all software packages with a large user base. The advancement of these software packages is explicitely planned for in the work packages of this project.The project thus adresses computational algorithms (nonlinear implicit solvers and scale bridging), application software, and programming (PE, hybrid programming, accelerators).