An Anisotropic and Gradient-Enhanced Damage Model for High-Cycle Fatigue Cyclic loading arises in numerous engineering applications, including aircraft wings and fuselage structures. Accurately modeling material behavior under complex cyclic loading is essential not only for efficient structural design but also for risk assessment. A particular motivation for this investigation is forming-induced damage and its influence on the fatigue behavior. To this end, the present study introduces a continuum damage mechanics-based framework for high-cycle fatigue in metallic materials that is applicable to both controlled laboratory experiments and complex service load histories. In the high-cycle fatigue regime, material deterioration is typically associated with quasi-brittle behavior. From a macroscopic perspective, damage is primarily driven by the elastic energy. To account for this behavior, the endurance surface concept is incorporated into an established framework based on the effective configuration approach [1-2]. The formulation ensures thermodynamic consistency while accounting for spatial gradients of the damage variable through a micromorphic extension, thereby achieving physically meaningful and mesh-independent results [3]. First, the model's capabilities are demonstrated for monotonic loading, using concrete as an example. Then, the model is extended to cyclic conditions, by the example of S-N curves for low-alloy steel. The predictive capabilities of the model are studied through several benchmark problems, with a special emphasis on non-proportional cyclic loading. These loading conditions can arise in practical applications through varying or even uncertain load paths. The framework's ability to capture anisotropic damage evolution is finally demonstrated, highlighting its suitability for complex fatigue modeling applications. [1] Ottosen, N. et al., Continuum approach to high-cycle fatigue modeling, International Journal of Fatigue, 30, 996-1006, 2008. [2] Menzel, A. et al., Anisotropic damage coupled to plasticity: Modelling based on the effective configuration concept, International Journal for Numerical Methods in Engineering, 54, 1409-1430, 2002. [3] Forest, S., Micromorphic Approach for Gradient Elasticity, Viscoplasticity, and Damage, Journal of Engineering Mechanics, 135, 117-131, 2009.