Multiscale thermoplastic analysis in the solidification zone

凝固区的多尺度热塑性分析

• 批准号: 456852487
• 负责人: Professorin Dr.-Ing. Lisa Scheunemann
• 金额: --
• 依托单位: Institut für Mechanik
• 依托单位国家: 德国
• 项目类别: Research Units
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/456852487?language=en
• 关键词: Multiscale; thermoplastic; analysis; solidification; zone

As a flexible and contact-free joining technology, laser beam welding has increasingly gained importance. Processing of alloys with large melting range poses a challenge due to their solidification cracking tendency. Solidification cracks form due to critical stress and strain states of the dendritic microstructure with interdendritic melt. Despite the high industrial relevance, there are only approaches addressing single aspects of the problem, metallurgically or structurally oriented. The research unit “Solidification Cracking during Laser Beam Welding – High Performance Computing for High Performance Processes” aims at developing quantitative process understanding of the mechanisms of solidification cracking and their relation to process parameters.Since a full-field resolution of the dendritic microstructure with interdendritic melt, taking into account the physical mechanisms prevailing here, would lead to immensely large systems of equations that do not allow efficient simulation of the process, a direct homogenization method, the FE²-method, is applied. This establishes a link between the dendritic solidification zone on the microscale and the macroscale on the component level. In close cooperation with TP 5 this project is dedicated to multi-scale and multiphysical modelling of the processes in the mixture zone in the forefront of the solid-liquid interface, where the critical zone for the formation of solidification cracks is located. In the multi-scale approach of the FE²-method for thermomechanically coupled problems, at each macroscopic integration point microscopic boundary value problems (in the form of representative volume elements, RVEs) are attached and solved under energetically consistent boundary conditions and the associated material response on the macroscale is obtained through evaluation of suitable surface integrals of the RVEs. To reduce the complexity of the RVEs, statistically similar representative volume elements (SSRVEs) are used, whose construction is based on the phase field simulations of the dendritic microstructure of TP 6. By means of thermoplastic material laws, the material behaviour of the individual phases is recorded on the microscale. The modelling on the macroscale demands the consideration of the influence of the laser beam as well as further boundary conditions, which are incorporated from the other subprojects. The efficient implementation of the multiscale approach requires the cooperation especially with the applicants Klawonn/Lanser, which enables the use of the algorithms on high performance computers. This approach allows a predictive analysis of the formation of solidification cracks on the basis of local state variables of the microstructure as a function of macroscopic process parameters.

激光焊接作为一种灵活、无接触的连接技术，越来越受到人们的重视。大熔点合金的凝固开裂倾向给其加工带来了挑战。凝固裂纹的形成是由于枝晶组织的临界应力和应变状态以及枝晶间熔体。尽管与工业高度相关，但只有从冶金或结构方面解决问题的单一方面的办法。“激光束焊接过程中的凝固开裂——高性能工艺的高性能计算”研究单位旨在对凝固开裂机理及其与工艺参数的关系进行定量的工艺理解。由于考虑到这里普遍存在的物理机制，对枝晶间熔体的枝晶微观结构的全场分辨率将导致无法有效模拟该过程的巨大方程组，因此应用了直接均匀化方法，即FE²-方法。这在微观和宏观的枝晶凝固区之间建立了联系。在与TP 5的密切合作下，该项目致力于对固液界面前沿的混合区域的过程进行多尺度和多物理建模，该区域是凝固裂纹形成的关键区域。在热力耦合问题的多尺度有限元方法中，在能量一致的边界条件下，在每个宏观积分点附加并求解具有代表性的体积元形式的微观边值问题，并通过对体积元的合适表面积分进行评价，得到宏观尺度上的相关材料响应。为了降低rrves的复杂性，采用统计相似的代表性体积元（SSRVEs），其构建基于tp6枝晶微观结构的相场模拟。利用热塑性材料定律，在微观尺度上记录了各个相的材料行为。在宏观尺度上的建模需要考虑激光束的影响以及从其他子项目中引入的进一步的边界条件。多尺度方法的有效实施需要特别与申请人Klawonn/Lanser合作，这使得算法能够在高性能计算机上使用。这种方法可以根据微观组织的局部状态变量作为宏观工艺参数的函数，对凝固裂纹的形成进行预测分析。