13th International Conference on Fracture June 16–21, 2013, Beijing, China -5- * * τ τ σ σ K K K K = (5) Figure 5 Relationship between A25 , A50 ,y FEM y FEM σ σ , A25 , A50 , xy FEM xy FEM τ τ and r when σ0 = 1MPa Figure 6 Relationship between A25 0, A50 0, y FEM y FEM σ σ , A25 0, A50 0, xy FEM xy FEM τ τ and emin when σ0 = 1MPa Figure 7 Relationship between A25 , A25 90 , y FEM y FEM σ σ − , A25 , A25-90 , xy FEM xy FEM τ τ and r when σ0 = 1MPa Figure 8 Relationship between A25 0, A25-90 0, y FEM y FEM σ σ , A25 0, A25-90 0, xy FEM xy FEM τ τ and emin when σ0 = 1MPa 4. Debonding fracture criterion based on the intensity of singular stress field Figure 9 shows the relation between 1 A25 1 = = P P K Kσ σ and 2l , where 1=P Kσ is the intensity of the singular stress field under P = 1N, and 1 A25 =P Kσ is the 1=P Kσ of the specimen A25. When the 2l is larger than 15mm, the 1=P Kσ tends to decrease. Figure 10 shows the relation between A25 c c K Kσ σ and 2l , where c Kσ is the intensity of the singular stress field under P = Pa f , and A25 c Kσ is the c Kσ of the specimen A25. When the 2l is smaller than 15mm, the A25 c c K Kσ σ tends to increase. However, when the 2l is larger than 15mm, the A25 c c K Kσ σ becomes constant irrelevant to the 2l . That is because the fracture mode changed from the cohesive fracture to the adhesive fracture. It is confirmed that the solid line is the average of A25 c c K Kσ σ of all specimens except for specimens A10 and A15. The open circle marks are distributed near the solid line within about 10% error. Figure 11 shows the relation between 1 A25 1 = = P P K Kσ σ and 2t . When the 2t is larger than 45mm, the 1 A25 1 = = P P K Kσ σ almost becomes constant. Figure 12 shows the relation between
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