13th International Conference on Fracture June 16–21, 2013, Beijing, China -10- Table 2. Comparison of measured and calculated load bearing capacities of the dissimilar joints TS KS2-0° KS2-30°KS2-60°KS2-90° CP Fmax,av Exp. 12.16 kN 13.57 kN 6.20 kN 4.67 kN 4.20 kN 1.66 kN Fmax Sim. 12.19 kN 13.78 kN 6.56 kN 4.64 kN 4.51 kN 1.43 kN Deviation in % + 0,25 + 1,55 + 5,81 - 0,64 + 7,38 -13,86 Figure 14. Calculated pull-out fracture of KS2-90° specimen (left and middle). Polished and etched cross- section of a tested KS2-90° specimen showing fracture inside the coarse grain HAZ of 22MnB5 (right) Based on the simulations of TS- and KS2-specimens the applied loads were decomposed into axial and shear forces according to the current loading angles during deformation of the specimens as shown in Fig. (15). It can be seen that the loading angles of all specimens, except the KS2-90° specimen, which is loaded under pure axial forces, deviate from their original values due to rotation of the weld nuggets during deformation. In KS2-60° and KS2-30° tests only minor rotations of the weld occur. Therefore the deviation from their original loading angle is negligible. In this case the measured load bearing capacities from experiments could be directly decomposed into their components to be used as values for the adjustment or construction of force-based failure criteria. In shear loading conditions larger weld rotations were observed. Up to the maximum forces rotations of 12.2° and 9.6° were calculated for TS- and KS2-0° specimens respectively. Caused by the rotation the axial forces acting on the joints increase to 2.6 kN for TS- and 2.3 kN for KS2-0° specimens. The assumption of constant loading angles for the adjustment or the construction of simplified force based failure criteria should not be made in this case, but can be taken from numerical simulations. Figure 15. Decomposition of measured and calculated load bearing capacities into axial and shear forces acting on the joint. The evolution of axial and shear forces during deformation of the specimens in simulations are shown by the dashed black lines
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