R-curve and traction-separation relation are commonly used to characterize the fiber bridging, which is significant toughening mechanism in composite laminates. Current investigations are mainly focused on unidirectional laminates. However, the dependence of the R-curve and traction-separation relation on the stacking sequence is still lack of comprehensive studies. Here, the effect of stacking sequence on the R-curve and traction-separation relation in unidirectional and multidirectional CFRP DCB laminates with designed generic +θ°/-θ° and 0°/θ° interfaces were systematically investigated, and interpreted combining with the fractographical analysis of failed fracture surface. Experimental results showed the fiber bridging length, steady-state fracture toughness and maximum bridging stress were strongly influenced by the stacking sequence. However, there was no clear relationship between them and the stacking sequence. In addition, the maximum bridging stress increased with the flexural modulus while a reverse trend presented in the relation between the maximum COD at the end of the fiber bridging zone and the flexural modulus. The obtained traction-separation relations were finally integrated into a tri-linear cohesive zone model. Numerical results from this model agreed well with the test results, which illustrated that the proposed cohesive zone model was applicable for delamination modelling in composite laminates with the effect of fiber bridging.

R曲线和牵引分离关系通常用于表征纤维桥接，这是复合材料层压板中重要的增韧机理。当前的研究主要集中在单向层压板上。然而，R曲线和牵引力-分离关系对堆垛顺序的依赖性仍然缺乏全面的研究。在此，堆叠顺序对R的影响系统地研究了设计了通用+θ°/-θ°和0°/θ°界面的单向和多向CFRP DCB层压板的曲线和牵引力-分离关系，并结合断裂断面的分形分析进行了解释。实验结果表明，纤维搭桥长度，稳态断裂韧性和最大搭桥应力受堆垛顺序的影响。但是，它们与堆叠顺序之间没有明确的关系。另外，最大桥接应力随挠曲模量而增加，而在纤维桥接区末端的最大COD与挠曲模量之间的关系呈现出相反的趋势。最终将获得的牵引分离关系整合到三线性粘聚区模型中。