13th International Conference on Fracture June 16–21, 2013, Beijing, China -3- are shown in Fig. (2). By using a pin-joint connecting the grips with the specimens fixtures no additional constraining forces arise during loading and only the applied vertical force acts on the joint. Figure 2. Coach-peel and KS2-specimens with loading angles 0°, 30°, 60° and 90° (left). Clamping conditions for the KS2-specimens tested under different loading angles (right) [9] Assuming constant loading angles Φ, defined as the angle between the joining plane and the loading direction during deformation of the specimens, the measured forces F in KS2-experiments can be decomposed into their axial FN and shear FS parts as φ sin = ⋅ F F N , φ cos = ⋅ F F S . (1) Based on this decomposition simplified force-based failure criteria for spot welded joints as proposed by several authors [4][10][11] can be constructed. Fig. (3) (left) shows the force vs. displacement curves of all the KS2-experiments carried out on the investigated dissimilar spot welded joint. The decomposition of their load bearing capacities assuming constant loading angles is shown on the right. The gray dashed circular lines in Fig. (3) (right) indicate lines of constant resulting forces. The highest maximum load of the joint was measured under shear loading conditions in experiments on KS2-0° specimens. With increasing loading angles the load bearing capacity of the joint decreases to a minimum of 4.2 kN under pure axial loading in KS2-90° tests. Fracture of all tested specimens occurred as pull-out fracture from the hot-stamped 22MnB5 sheets. Cross-sections of failed specimens, loading capacities and results of TS- and CP-specimens will be shown in section 3.3. Figure 3. Force vs. displacement curves of KS2-specimens with loading angles 0°, 30°, 60° and 90° (left). Decomposition of load bearing capacities of the KS2 experiments into axial and shear forces (right)
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