Experimentelle und modellmäßige Bewertung der dreidimensionalen Auswirkung mikrostruktureller Barrieren während der Rissinitiierungphase VHCF-beanspruchter Werkstoffe

即使在十亿次循环之后，由金属材料制成的部件也可能显示出塑性变形的痕迹而不会失效。然而，相同的部件可以在相同的载荷下断裂，但循环次数较少。本研究的假设，即微观结构的障碍位错运动的阻力决定了疲劳损伤的发生将被量化的铁素体和奥氏体相的不同强度的双相钢。此外，重要的方面，如同时塑性和残余应力分布之间的两相，以及随机排列的疲劳临界微观结构集群将进行分析。关于环境效应对VHCF损伤的影响这一重要问题将通过在不同气氛下的实验来解决。使用三种相互作用的现代实验和理论方法：（i）结合原位分析技术的超声波疲劳测试（ii）使用高能同步辐射的三维微观结构重建和空间分辨衍射测量，以及（iii）作为损伤基础的两相微观结构内的弹性和塑性各向异性疲劳变形的有限元建模-VHCF制度的容限寿命预测概念以及抗疲劳材料结构优化的可能性。

Even after one billion cycles, components made of metallic materials may show traces of plastic deformation without being failed. However, the same components can fracture at the same load but a lower number of cycles. The hypothesis of the present research that the resistance of microstructural barriers to dislocation motion decides about the occurrence of fatigue damage will be quantified by duplex steel of different strength of the ferrite and austenite phase. Furthermore, important aspects, such as the simultaneous plasticity and residual stress distribution between the two phases, as well as the stochastic arrangement of fatigue-critical microstructural clusters will be analyzed. The important question about the influence of environmental effects on the VHCFdamage is going to be addressed by experiments in different atmospheres. Three interacting modern experimental and theoretical approaches are used: (i) ultrasonic fatigue testing in combination with in-situ analysis techniques (ii) three-dimensional microstructural reconstruction and spatially-resolved diffraction measurements using high energy synchrotron radiation and (iii) finite element modeling of the elastic and plastic anisotropic fatigue deformation within the twophase microstructure as a base of a damage-tolerant life prediction concept for the VHCF regime as well as an possibility for structural optimization of fatigue-resistant materials.