Failure in adhesive joints is usually the result of a non-uniform distribution of stress, which is observed with maximum values near the two ends of the overlap, and the central parts have a minor overall load-bearing contribution. In the joint of two dissimilar materials, the stress fields are asymmetric and the optimum grading of the adhesive properties will not be symmetric. The main objective of this work was to study the performance of optimum functionally graded joints (OFGJ) to maximize the ultimate loading capacity of a lap shear joint. The adherends were aluminum 7075-T6 and unidirectional glass-epoxy composite. The study has been performed considering a grading strategy based on mixtures of an epoxy resin with different values of liquid rubber to obtain the properties variations. First, the mono-adhesive joints with homogeneous bond-line and then symmetrical graded joints with equal bands were investigated. A compliance-based optimization method with the normalized shear stress distribution was used to obtain the best properties along the bond-line. The elastic-plastic model and mixed-mode cohesive damage model were used to obtain the stress distribution and failure prediction, respectively. By grading the overlap symmetrically, the stress distribution has become more uniform and the failure load compared to the base specimen (with a shear strength of 6 kN), increased by 206%. Optimization of adhesive properties using normalized shear stress distribution has positive effects on modifying stress distribution, non-shear forces elimination, improvement of the load-bearing contribution, failure mode alteration, and delay on adhesive joints failure. Therefore, there is a high increase in shear load strength of optimum graded specimen by a significant amount of 299%.

粘合接头的失效通常是应力分布不均匀的结果，这种应力分布在重叠的两端附近均达到最大值，而中心部位的整体承载力贡献较小。在两种不同材料的接合处，应力场是不对称的，并且粘合性能的最佳等级将是不对称的。这项工作的主要目的是研究最佳功能梯度接头（OFGJ）的性能，以最大程度地提高搭接剪切接头的极限承载能力。被粘物是铝7075-T6和单向玻璃-环氧复合材料。进行这项研究时考虑了基于环氧树脂与不同值的液态橡胶的混合物的分级策略，以获得性能变化。第一的，研究了具有均匀粘结线的单胶接接头，然后研究了具有等谱带的对称渐变接头。使用具有标准化剪应力分布的基于柔量的优化方法来获得沿粘结线的最佳性能。利用弹塑性模型和混合模式内聚损伤模型分别获得应力分布和破坏预测。通过对称地对重叠进行渐变，与基础样本（剪切强度为6 kN）相比，应力分布变得更加均匀，破坏载荷增加了206％。使用归一化剪切应力分布来优化粘合性能，对修改应力分布，消除非剪切力，改善承重贡献，改变破坏模式，并延迟了粘合接头的故障。因此，最佳梯度试样的剪切载荷强度大大提高了299％。