Adhesive joints are frequently used in automotive, maritime and construction applications, yet joint reliability remains a concern. The purpose of this study is to develop a fracture mechanics methodology for the failure of an elastic-brittle lap-shear joint comprising a thick adhesive layer (an epoxy, of thickness on the order of 10 mm) sandwiched between thick steel adherends. This configuration is of practical application to ship-building, such as the bonding of a superstructure to the underlying hull. A modified thick-adherend shear test (TAST) is designed, and specimens are fabricated, with a range of interfacial pre-crack length and a range of adhesive layer thickness. The failure of samples with no pre-crack is governed by a critical value of corner singularity, whereas the failure of samples with long pre-cracks is governed by a critical value of interfacial stress intensity factor. Predictions for the dependence of failure load upon layer thickness and pre-crack length are obtained by analysing the elastic stress state for both a corner singularity and for an interfacial crack. Both the experimental results and the theoretical framework are useful in the design and fabrication of reliable lap-shear joints that comprise a thick elastic adhesive layer.

胶粘接头通常用于汽车，海事和建筑应用中，但接头的可靠性仍然是一个问题。这项研究的目的是开发一种断裂力学方法，以解决弹性-脆性搭接剪切接头失效的问题，该接头包括夹在厚钢被粘物之间的厚胶层（环氧树脂，厚度为10毫米左右）。该构造在造船中具有实际应用，例如将上层建筑与下层船体粘合在一起。设计了一种改进的厚粘附体剪切试验（TAST），并制造了具有一定范围的界面预裂纹长度和一定范围的粘合剂层厚度的试样。没有预裂纹的样品的失效取决于拐角奇点的临界值，预裂纹较长的样品的破坏取决于界面应力强度因子的临界值。通过分析拐角奇点和界面裂纹的弹性应力状态，可以得出破坏载荷对层厚和裂纹前长度的依赖性的预测。实验结果和理论框架都可用于设计和制造可靠的搭接剪切接头，该接头包括厚的弹性粘合剂层。