The present work aims to assess the joint behaviour of friction stir spot welded sandwich sheets by changing the quality of the epoxy core layer. Lab scale experiments and numerical simulations are conducted for the purpose. The core property is altered by varying hardener to resin (h/r) ratio within a suitable range. Joint mechanical performance and joint characterization are evaluated from experiments. Cohesive zone modelling has been incorporated in Abaqus to monitor the hook formation and interface delamination, which is not performed until now in literature. The core quality influences the behaviour of sandwich sheet and hook geometry significantly. Desired h/r ratio is also evaluated from such results, and FSSW is found advantageous at some h/r ratios. The failure mode is independent of h/r ratio and loading conditions. The final joint shape and hook geometry obtained from FE simulations agree well with that of from experiments. Cohesive zone modelling helped in accurate prediction of delamination, and without it, the hook geometry and plastic energy dissipation predictions are approximated. It has been suggested to incorporate cohesive zone model during FE simulations to have a realistic prediction of sandwich joint performance.

本工作旨在通过改变环氧芯层的质量来评估搅拌摩擦点焊夹芯板的接头性能。为此目的进行了实验室规模的实验和数值模拟。通过在合适的范围内改变固化剂与树脂的比值（h / r），可以改变核心性能。联合机械性能和联合表征是通过实验评估的。Abaqus中已经集成了粘性区域建模，以监视挂钩的形成和界面的分层，这在文献中至今还没有执行。芯的质量显着影响夹心板的性能和钩形。从这些结果还可以评估所需的h / r比，发现FSSW在某些h / r比下是有利的。失效模式与h / r比和负载条件无关。通过有限元模拟获得的最终接头形状和弯钩几何形状与实验结果非常吻合。内聚区建模有助于准确地预测分层，如果没有它，钩形和塑性能耗散的预测就可以近似了。有人建议在有限元模拟过程中结合粘性区域模型，以对夹层接头的性能做出现实的预测。