có nghĩa là chất kết dính thực sự hoạt động như một kim loại mỏng manh. Nếu nó đã làm, nó sẽ dỡ bỏ với một bù đắp lâu dài, thực sự, nó unloads trễ nhưng hầu như nguồn gốc) Kết quả phân tích đàn hồi-nhựa mới, tài liệu trong tài liệu tham khảo [7], được mô tả trong hình 8,22, trong dimensionalized không cùng một hình thức như đối với giải pháp đàn hồi của Rose trong hình | Chapter 8. Recent expansions in the capabilities of Rose s closed-form analysis 201 ARCTAN G ADHESIVE SHEAR STRESS mean that the adhesive actually behaves like a ductile metal. If it did it would unload with a permanent offset actually it unloads with hysteresis but almost to the origin. The results of the new elastic-plastic analysis documented in reference 7 are depicted in Figure in the same non-dimensionalized form as for Rose s elastic solution in Figure . The value 1 on the ordinate of Figure represents the elastic solution. It is clear that the added strain energy of ductile adhesives with respect to brittle ones with no non-linear capacity is to reduce the stiffness of the load over the Fig. . Effect of elastic-plastic adhesive behavior on crack-tip stress intensity factors underneath bonded patches. ADHESIVE A PLASTIC-TO- ELASTIC - STRAIN RATTO Ip A á RATIO OF ELASTICPLASTIC TO ELASTIC STRESS INTENSITY FACTORS K_ ADHESIVE SHEAR STRAIN 7 LOCUS OF INTERSECTIONS WHEREk 1 . TRANSITIONAL CRACK LENGTH WHEN COD REACHES LIMIT SET BY THE ADHESIVE BOND k 0123456789 10 NONDIMENSIONALIZED HALF-CRACK LENGTH a A ---ữ .. ÃDHEStVt r CHARCTERISTICS OF UNPATCHED SKIN CRACK AT INCREASING LOAD LEVELS elastic ADHESIVE Fig. . Elastic-plastic representation of adhesive non-linear behavior in shear. 202 Advances in the bonded composite repair of metallic aircraft structure crack for sufficiently high loads. This of course is undesirable since it increases the stress intensity K. On the other hand the same added flexibility goes hand-inhand with increased joint strength enabling bonded patches to be applied to thicker cracked structure than can be repaired with elastic adhesives - unless one is willing to employ stepped patches to decrease the load transferred per step and at the same time decrease the eccentricity in load patch for one-sided patches. The new longer effective half-crack tips and higher stress-intensity factors have been derived in 7 as
