Multiple delamination planes can form when a composite structure is subjected to out-of-plane stresses during static over-loading or impact loading. Numerical modelling of such events is often prohibitively expensive because large numbers of cracks can co-exist and interact, and fracture models usually affect the time step size in explicit solutions. Here a new method called Adaptive Mesh Segmentation is proposed, which introduces segmentation ‘on-the-fly’ in meshes of quadratic finite elements with six degrees of freedom per node, without any intervention from the user and without any reductions in time step size for solution stability. A novel cohesive formulation with rotational degrees of freedom is introduced which increases the resolution of the numerical cohesive zone and allows the use of relatively coarse meshes. Once a critical stress criterion is met, new degrees of freedom are added at element boundaries to model strong discontinuities. A new moment–damage relationship is proposed to link the discontinuity in rotational degrees of freedom with the cohesive zone law which is translational by definition. A method for initiating cohesive tractions and moments with minimal disturbances to the surrounding stress field is also presented. Finally, the model is applied in the analysis of composite delamination benchmarks using relatively coarse meshes and modest model sizes. Considerable improvements in accuracy are observed when compared to conventional methods.

当复合结构在静态超负荷或冲击负荷期间承受平面外应力时，会形成多个分层平面。由于大量裂缝可以共存并相互作用，因此此类事件的数值建模通常过于昂贵，并且破裂模型通常会在显式解决方案中影响时间步长。在这里，提出了一种称为自适应网格分段的新方法，该方法在每个节点具有六个自由度的二次有限元网格中“动态”地进行分段，而无需用户干预，也不会减少时间步长。溶液稳定性。引入了具有旋转自由度的新型粘性配方，该配方提高了数字粘性区域的分辨率，并允许使用相对粗糙的网格。一旦满足了临界应力准则，就会在单元边界处添加新的自由度以对强不连续性进行建模。提出了一种新的矩-损关系，以将旋转自由度的不连续性与内聚力定律联系起来，后者根据定义是平移的。还提出了一种在对周围应力场的干扰最小的情况下启动粘性牵引力和力矩的方法。最后，该模型用于使用相对粗糙的网格和适度的模型大小来分析复合材料分层基准。与传统方法相比，可以观察到准确性的显着提高。提出了一种新的矩-损关系，以将旋转自由度的不连续性与内聚力定律联系起来，后者根据定义是平移的。还提出了一种在对周围应力场的干扰最小的情况下启动粘性牵引力和力矩的方法。最后，该模型用于使用相对粗糙的网格和适度的模型大小来分析复合材料分层基准。与传统方法相比，可以观察到准确性的显着提高。提出了一种新的矩-损关系，以将旋转自由度的不连续性与内聚力定律联系起来，后者根据定义是平移的。还提出了一种在对周围应力场的干扰最小的情况下启动粘性牵引力和力矩的方法。最后，该模型用于使用相对粗糙的网格和适度的模型大小来分析复合材料分层基准。与传统方法相比，可以观察到准确性的显着提高。该模型用于使用相对粗糙的网格和适度的模型大小分析复合材料分层基准。与传统方法相比，可以观察到准确性的显着提高。该模型用于使用相对粗糙的网格和适度的模型大小分析复合材料分层基准。与传统方法相比，可以观察到准确性的显着提高。