# Fatique Crack Growth Studies under Mixed-Mode Loading in AISI 316 Stainless Steel
## 3 Numerical Results and Discussions
### Compact Tensile Shear (CTS) Specim
This means that the crack tends to propagate perpendicular to the crack surface. As the loading angle increases to 45 degrees, the ratio of _K\({}_{I}\)_ to _K\({}_{II}\)_ decreases, and both modes become more comparable. This change in the _K\({}_{I}\)_-to-_K\({}_{II}\)_ ratio can significantly affect the crack growth direction. At a loading angle of 60 degrees, the ratio of _K\({}_{I}\)_ to _K\({}_{II}\)_ is smaller compared to the previous angles of 30 and 45 degrees. This means that KII becomes the dominant factor. As a result, the crack tends to propagate parallel to the crack surface, rather than perpendicular to it, as in the case of _K\({}_{I}\)_ dominance. Therefore, the choice of loading angle for a CTS specimen is critical in determining the fracture behavior of a material, and it is important to consider the expected loading conditions when selecting the appropriate angle for testing. By choosing the appropriate loading angle, we can ensure that the stress-intensity factors are accurately captured, and the fracture toughness of the material is adequately measured. Figure 4:1 A comparison of fatigue life for loading angle \(60^{\circ}\), experimental [36] versus simulated results. The von Mises stress in a CTS specimen is calculated based on the normal and shear stresses acting on the specimen. In CTS specimens, the normal stress is typically oriented perpendicular to the crack plane and can cause the specimen to deform in tension or compression. On the other hand, the shear stress is typically oriented parallel to the crack plane. The shear stress is typically oriented parallel to the crack plane, and the shear stress is typically oriented perpendicular to the crack plane. Figure 4:2 Comparison of the opening mode of SIF (\(K_{l}\)) for different loading angles. Figure 4:3 Comparison of the in-plane shear mode of stress-intensity factor (\(K_{l}\)) for different loading angles. plane and can cause the specimen to deform in shear. When a CTS specimen is subjected to a load at an angle to the crack plane, it experiences both normal and shear stresses. The normal stress component is highest when the load is applied perpendicular to the crack plane (i.e., when the loading angle is 0\({}^{\circ}\) or 90\({}^{\circ}\)), while the shear stress component is highest when the load is applied parallel to the crack plane (i.e., when the loading angle is 45\({}^{\circ}\)). As depicted in Figure 14, the von Mises stress in a compact tension shear (CTS) specimen is highest when the load is applied at a 45\({}^{\circ}\) angle. This is due to the fact that this loading angle maximizes the combined effect of both normal and shear stresses acting on the specimen. The von Mises stress is lower for loading angles of 30 and 60 degrees, as these angles result in less combined stress on the specimen. It is important to note that the relationship between the von Mises stress and the loading angle can be affected by various factors, including the material properties of the specimen, the size and shape of the crack, and the magnitude and direction of the applied load. The von Mises stress can also provide insights into the failure mechanisms of CTS specimens under different loading angles. By analyzing the von Mises stress distribution, researchers can identify the critical points where the material will start to deform and eventually fail. This information can help improve the understanding of the fracture behavior of the material. According to Figure 15, an increase in the corresponding shear stress component was observed at loading angles of 30 and 60 degrees, indicating a higher degree of shear loading in the compact tension shear specimen. This result is consistent with the general trend of an increased shear stress component with increasing loading angles. In contrast, at a loading angle of 45 degrees in the compact tension shear specimen, the shear stress component is typically at its maximum value.