Composites materials like jute/epoxy exhibit high hardness and are considered as difficult-to-machine materials. As a result, alternatives to conventional machining become essential to post-process the composites. Accordingly, due to its non-thermal nature, abrasive water jet machining has recently come to be seen as one of the most promising machining methods for composite materials. In the current study, the impact of machining parameters such as traverse speed (TS), standoff distance (SOD) and abrasive mass flow rate (MFR) on machined surface roughness (Ra) has been investigated. In addition, the optimum combination of process parameters to machine a jute fiber-reinforced polymer composite with minimum Ra is predicted. The experimental results are analyzed using Taguchi and Response Surface Methodology (RSM) approaches to determine the optimum set of process parameters to achieve the lowest roughness values. Without making any changes in the machining conditions, the optimum set of values is determined for two conditions by reinforcing the fiber with 45° inclination and 90° inclination. The results reflect the different optimum combinations for each fiber inclination. For 45° fiber inclination, to achieve the minimum Ra value, the predicted combination is TS = 30 mm/min, SOD = 2 mm and MFR = 0.35 kg/min. When the fiber inclination is 90°, the predicted optimum combination is TS = 25 mm/min, SOD = 2 mm, and MFR = 0.35 kg/min. It is evident from the results that the optimum combination will be changed according to the machining conditions as well as material properties. The results confirm the effect of fiber orientation on surface roughness. The specimen with 45° fiber inclination produces a lower Ra with an average of 4.116 µm, and the specimen with 90° fiber inclination generates a higher Ra with an average of 4.961 µm.

Metal and polymer interface bonding significantly influences the mechanical performance of fiber metal laminates (FMLs). Therefore, the effect of surface treatments (mechanical abrasion, nitric acid etching, P2 etching, sulfuric acid anodizing (SAA), and electric discharge machine (EDM) texturing) carried on aluminum 2024-T3 alloy sheets was evaluated considering surface morphology, surface topography, and surface roughness. Further, the influence of surface treatments on interfacial adhesion strength and failure mode between the aluminum alloy and carbon fiber prepreg was investigated. The surface treatments increased the surface roughness of the aluminum substrates. Surfaces treated using SAA, nitric acid, and P2 etchant showed improved wettability, while mechanically abraded and EDM textured substrates showcased hydrophobic behavior. The selected surface treatments significantly affected interfacial adhesion between the epoxy polymer and aluminum alloy. SAA and EDM texturing greatly enhanced the interfacial peel strength of FMLs. In the case of interfacial shear strength, EDM textured substrate showed superior performance, followed by SAA. Moreover, untreated and mechanically abraded specimens exhibited weaker bonding and adhesive failure at the aluminum-epoxy interface, whilst chemical treatments resulted in mixed model failure. EDM textured surface underwent cohesive failure, while a dominant mixed mode failure and fiber adhesion were observed in the SAA-treated specimen.