In the framework of lightweight structures, the bonded joints appear as a suitable solution for increasing the mass-to-strength ratio. However, the full understanding of the interface debonding is a key obstacle to be overcome in critical systems. For characterizing adhesive-to-adherend interface crack initiation, the three-point bending test has been shown as a useful test that provides an identifiable small round zone. The samples were manufactured using an aluminum alloy 2024-T3 etched with nitric acid. The adhesive consisted in an epoxy pre-polymer DGEBA, DETA amine and an organosilane GLYMO directly introduced in the mixture. A coupled stress and energy criterion was used for the assessment of the properties of the interfacial debonding, since a stress concentration appears near to the corner of the specimen. For a quick computation, the application of the coupled criterion (CC) used the macro-element technique. On the other hand, most finite–element-based software has already implemented the cohesive zone modeling (CZM). In this sense, the fracture parameters computed via CC were used for the assessment of cohesive zone modeling of adhesive-to-adherend interface crack initiation. The results of fracture initiation using the CZM showed a good agreement in a macroscale response with the experimental campaign, thus providing a useful tool for a rapid estimation of cracking initiation.

中文翻译：

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一种基于耦合准则的粘合剂-被粘合剂界面裂纹萌生评估方法

在轻型结构的框架中，粘合接头似乎是提高质量强度比的合适解决方案。然而，对界面脱粘的充分理解是关键系统中需要克服的关键障碍。为了表征粘合剂与粘合剂界面裂纹的萌生，三点弯曲试验已被证明是一种有用的试验，可提供可识别的小圆形区域。样品是使用用硝酸蚀刻的铝合金 2024-T3 制造的。粘合剂由环氧预聚物 DGEBA、DETA 胺和直接引入混合物中的有机硅烷 GLYMO 组成。由于应力集中出现在试样的角附近，因此使用耦合应力和能量准则来评估界面剥离的特性。为了快速计算，耦合准则 (CC) 的应用使用了宏单元技术。另一方面，大多数基于有限元的软件已经实现了内聚区建模 (CZM)。从这个意义上说，通过 CC 计算的断裂参数用于评估粘合剂与粘合剂界面裂纹萌生的内聚区建模。使用 CZM 的裂纹萌生结果表明，宏观响应与实验活动具有良好的一致性，从而为快速估计裂纹萌生提供了有用的工具。通过 CC 计算的断裂参数用于评估粘合剂与粘合剂界面裂纹萌生的内聚区模型。使用 CZM 的裂纹萌生结果表明，宏观响应与实验活动具有良好的一致性，从而为快速估计裂纹萌生提供了有用的工具。通过 CC 计算的断裂参数用于评估粘合剂与粘合剂界面裂纹萌生的内聚区模型。使用 CZM 的裂纹萌生结果表明，宏观响应与实验活动具有良好的一致性，从而为快速估计裂纹萌生提供了有用的工具。