13th International Conference on Fracture June 16–21, 2013, Beijing, China -8- 3.3. Simulation of tensile-shear-, KS2- and coach-peel tests For the simulation of deformation and failure behavior of dissimilar spot welded joints in tensile-shear- (TS), KS2- and coach-peel (CP) tests, the calibrated material and failure models were used for the different material zones of the weld. Due to the negligible differences in the mechanical behavior between the base material of 22MnB5 and the weld metal as well as the similar hardness values of the base metal, the weld metal and the non-softened HAZ in 22MnB5, the mechanical properties of the non-softened HAZ were assumed to be identical to those of the weld metal. A detailed finite-element model of the spot weld, shown in Fig. (10), was built up taking into account the geometry of the weld and its material zones measured in etched cross-sections and hardness measurements of spot welded specimens (see Fig.(1)). The nugget diameter and the diameter of the HAZ of the spot weld were modeled as 5.2 mm and 6.6 mm respectively. The softened HAZ in the hot-stamped 22MnB5 sheet was modeled with a width of 0.6 mm. The edge length of the elements in the spot welded region is approximately 0.1 mm. Figure 10. Detailed finite element model of the spot weld between 22MnB5 and HC340LAD The finite-element models of TS-, KS2- and CP-specimens are shown in Fig. (11). Due to the symmetry only one half of each specimen was modeled. The parts of the specimens that are clamped in the experiments, shown in dark gray, are taken as rigid bodies. The grips and the specimen fixtures of the KS2-tests were not explicitly taken into account. Instead of that the clamping conditions of the specimens have been modeled by connecting all nodes of the clamped rigid bodies via kinematic constraints to one node representing the pin-joint between the specimen fixtures and the grips (see Fig. (2)). This is shown schematically in Fig. (11). (a) (b) (c) (d) (e) (f) Figure 11. Detailed finite element models of the spot welded tensile-shear specimen (a), KS2-0° (b), -30° (c), -60° (d), -90° (e) specimens and the coach-peel specimen (f)
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