Abstract The present paper provides a model for the stress analysis of double-lap adhesive joints with multilayered inner adherend. The effect of the stiffness of the adherends on the distribution of stresses in the adhesive layer is investigated. Bonding adhesively materials with different stiffnesses (e.g. glass and plastic materials) leads to a concentration of stresses and therefore failure in the less stiff layer. Failure, therefore, occurs in the adherend cross-section instead of in the adhesive joint (stock-break failure mode). An innovative concept is here introduced for the double-lap adhesive joint by inserting a plate reinforcement in the less stiff substrate. Numerical and FEM analyses are used for validation. The results show that the insertion of a reinforcement plate (e.g. steel plate) in the middle of the inner adherend (e.g. plastic material) allows a better stress transmission to the outer adherends (e.g. glass). Four different configurations with various reinforcement thickness are investigated and the obtained adhesive stress distributions are compared to the results of FE analyses. In general, a good agreement is observed. This model demonstrates that peak stress in the adhesive layer could be significantly reduced by the layering of the inner adherend. Thus, the proposed concept provides a way to optimize double-lap adhesive joints for enhanced strength keeping the less stiff adherend in the bonding interface.

中文翻译：

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双搭接粘接接头中的应力分布：被粘物增强层的影响

摘要 本文为多层内被粘物双搭接胶接头的应力分析提供了一种模型。研究了被粘物的刚度对粘合剂层中应力分布的影响。粘合具有不同硬度的材料（例如玻璃和塑料材料）会导致应力集中，从而导致硬度较低的层失效。因此，失效发生在被粘物横截面而不是粘合剂接头（断料失效模式）。通过在硬度较低的基材中插入板加强件，这里为双搭接粘合接头引入了一个创新概念。数值和 FEM 分析用于验证。结果表明，在内部被粘物（如钢板）中间插入加强板（如钢板）塑料材料）可以更好地将应力传递到外部被粘物（例如玻璃）。研究了具有不同增强厚度的四种不同配置，并将获得的粘合应力分布与有限元分析的结果进行了比较。通常，观察到良好的一致性。该模型表明，通过内部被粘物的分层，可以显着降低粘合剂层中的峰值应力。因此，所提出的概念提供了一种优化双搭接粘合接头以增强强度的方法，以保持粘合界面中硬度较低的被粘物。研究了具有不同增强厚度的四种不同配置，并将获得的粘合应力分布与有限元分析的结果进行了比较。通常，观察到良好的一致性。该模型表明，通过内部被粘物的分层，可以显着降低粘合剂层中的峰值应力。因此，所提出的概念提供了一种优化双搭接粘合接头以增强强度的方法，以保持粘合界面中硬度较低的被粘物。研究了具有不同增强厚度的四种不同配置，并将获得的粘合应力分布与有限元分析的结果进行了比较。通常，观察到良好的一致性。该模型表明，通过内部被粘物的分层，可以显着降低粘合剂层中的峰值应力。因此，所提出的概念提供了一种优化双搭接粘合接头以增强强度的方法，以保持粘合界面中硬度较低的被粘物。