## 5 Conclusions  
To assess the fatigue life of planar imperfections, local approaches such as TCD, N-SIE, and ESED can be utilized on linear-elastic simulation results. In addition to constructing a new model for each load vector angle, two alternative methods were introduced, which both exhibited significantly reduced computational effort. This benefit in numerical efficiency was based mainly on the idea of keeping the mesh in the vicinity of the defect contour unchanged for varying uniaxial load vectors. The key functions of the implemented methods were discussed through representative examples, where the evaluation strategy involved distinguishing between sharp and blunt notch assessment. Even if the defect possesses a smooth geometry, the sharp notch evaluation procedure is computed for each defect point as V-notch; the corresponding opening angle is defined by the neighboring cell edges. Conversely, the blunt notch procedure evaluates the geometry close to the defect point and defines the notch radius and notch opening angle, which are subsequently used in the fatigue assessment. Thus, the local curvature is a key parameter in assessing the fatigue strength of planar imperfections under varying uniaxial load vectors. Moreover, the value of El Haddad's length, as an intrinsic material parameter related to the critical radius, affects the filter length applied in curvature evaluation. The material's notch sensitivity is, therefore, integrated into the blunt notch fatigue assessment approaches. Both the sub-case and superposition methods were shown to be applicable to all fatigue approaches, but preferences may be given as follows:  
* Notch stress intensity factor results using the computed boundary value are well-applicable, especially if the defect is evaluated as a blunt notch. A fine mesh-seed in the vicinity of the notch is encouraged in order to compute the boundary value by extrapolation. About three elements per length of critical radius are recommended. * Fatigue results by evaluating the stress field according to the Theory of Critical Distances are applicable to both methods, although the stress values along the vector path are interpolated from the mesh. * The elastic strain energy density evaluation is directly applicable to the sub-case approach. For the superposition method, the energy must be calculated from the transformed stress and strain tensor first. To obtain results with high accuracy, a mesh-seed value of about one-half to one-third of the control radius is sufficient. * The size of the surrounding bounding box of the input mesh should be about ten times the extent of the largest defect. The sub-case method splits the input model into  
Figure 29: Example of TCD evaluation of pore network following ASTM Standard E446 classA1 applying the sub-case method (mesh ‘ASTM_A1_quad_v1’): (**a**) Contour plots for load angle \(\varphi=100^{\circ}\); and (**b**) Course of evaluated Point Method stress values and load angle per defect. a circular section, covering the corresponding defect geometries. The superposition method retains the initial mesh during evaluation. * For planar models with mesh element count in the tens of thousands, the superposition method is more powerful, in terms of computation time. However, if the cell count is in the range of 100,000 or higher, the sub-case method is more applicable. * If results with high accuracy are targeted, instead of minimizing the computation time, the sub-case method should be used for all fatigue approaches. The stress results obtained by the superposition method may differ by about 10-15%, depending on the evaluated notch geometry and mesh-seed. As the Point Method evaluates stress values at points away from the notch tip, the difference is less pronounced with this method. The same recommendations on method order hold true in the case of the elastic strain energy density approach, although the loss in accuracy with the superposition method is less pronounced compared to the sub-case method.