Laser‐Dimpled Energy Directors for Enhanced Microwave Joining of PPS/Carbon Fiber Composites

ABSTRACT This study investigates the effect of laser‐dimpled energy directors (EDs) on the microwave joining performance of polyphenylene sulfide/carbon fiber (PPS/CF) composites. Laser dimples with depths of 0.1, 0.2, and 0.3 mm were introduced in the overlap region and compared with undimpled joints. The dimpled surface enhanced melt flow, interfacial contact, and mechanical interlocking, resulting in progressively improved joint performance with increasing dimple depth. The 0.3 mm dimple configuration exhibited the highest lap‐shear strength of 78 ± 3.72 MPa, corresponding to an improvement of approximately 117% over the undimpled joint (36 ± 1.79 MPa). Similarly, the absorbed impact energy increased from 14.67 ± 0.71 kJ/m ² for the undimpled joint to 24.18 ± 1.20 kJ/m ² for the 0.3 mm dimpled joint, representing an improvement of approximately 65%, while fractographic analysis revealed a transition from adhesive failure to cohesive failure within the composite adherend, confirming enhanced interfacial bonding.