The wide adoption of thermoplastic composites to reduce weight in structural parts requires reliable numerical methods to account for debonding between overmolded parts. Although cohesive elements are effective for debonding, the need for very fine meshes in the cohesive zone limits their practical use. In the present work, a novel structural cohesive element is proposed for the efficient modeling of debonding in thermoplastic composite panels with overmolded stiffeners. Three-node triangular Kirchhoff-Love shell elements are employed for the modelling of thin panels and stiffeners. The proposed cohesive element perpendicularly connects the shell elements representing the rib to those representing the plate. The displacement discontinuity is defined from the evaluation of the shell fields at the elements edges, while allowing for transmission of cohesive forces and cohesive couples. The model is verified for mode I, mode II and mixed-mode benchmark problems. A debonding problem is analyzed with both standard 3D cohesive elements and the proposed element. The results show that the element size in the proposed models can be much larger than that in the standard model, with more than 95% reduction in CPU time, while retaining prediction accuracy. The debonding analysis of a complex stiffened panel is also presented to demonstrate the intended use of the proposed element for simulating debonding in structural components.

翻译：热塑性复合材料在结构件减重中的广泛应用，需要可靠的数值方法处理包覆成型部件间的脱粘问题。尽管内聚单元能有效模拟脱粘，但内聚区所需极细网格限制了其实际应用。本文提出一种新型结构内聚单元，用于高效模拟含包覆成型加筋条的热塑性复合材料板脱粘。采用三点式基尔霍夫-洛夫三角形壳单元对薄板与加筋条进行建模。所提内聚单元垂直连接代表筋条的壳单元与代表板的壳单元。通过评估壳场在单元边界的值定义位移不连续性，同时允许传递内聚力和内聚力偶。模型经I型、II型及混合型基准问题验证。分别采用标准三维内聚单元与所提单元分析脱粘问题，结果表明：所提模型单元尺寸可远大于标准模型，在保持预测精度的同时CPU时间降低超95%。此外，通过对复杂加筋板的脱粘分析，展示了所提单元在结构件脱粘模拟中的预期应用。