This article proposes a formulation for the analysis of delamination and fracture propagation problems at the interelement interface, with perfect adhesion at the pre‐failure condition and with linear softening at the post‐failure regime. The proposed formulation is based on the hybrid equilibrium element (HEE) model, with stress fields which strongly verify the homogeneous equilibrium equations and interelement equilibrium equations. The HEE can easily model high‐order stress fields and can implicitly model the initially rigid behavior of an extrinsic interface at the element sides. The interface model is defined as a function of the same degrees of freedom of the HEE (generalized stresses) and the pre‐ and post‐failure behavior of the interface can be modeled without any additional degree of freedom. The proposed formulation is developed for a nine‐node triangular HEE with quadratic stress fields. This article also proposes an extrinsic cohesive model, rigorously developed in the damage mechanics framework.

中文翻译：

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带元素界面的混合平衡元件，用于分析分层和裂纹扩展问题

本文提出了一种用于分析元素间界面处的分层和裂缝扩展问题的公式，该公式在失效前状况下具有完美的附着力，在失效后状况下具有线性软化。所提出的公式基于混合平衡元素（HEE）模型，其应力场强烈验证了均质平衡方程和元素间平衡方程。HEE可以轻松地对高阶应力场进行建模，并且可以隐式地对单元侧面的外部界面的初始刚性行为进行建模。界面模型被定义为具有相同的HEE自由度（广义应力）的函数，并且可以在没有任何其他自由度的情况下对界面的失效前后行为进行建模。拟议的公式是针对具有二次应力场的九节点三角形HEE开发的。本文还提出了在损伤力学框架中严格开发的外部内聚模型。