Co-authors​ :

 Shi HANG (UNITED KINGDOM), Giasin KHALED (UNITED KINGDOM), Antigoni ANTIGONI BAROUNI (UNITED KINGDOM), Zhang ZHONGYI  

The development of bio-based composites made of natural fibres, such as jute, flax, and coconut fibre, is ongoing for various industries including automotive, construction, and aerospace. Natural fibres are utilised in the production of different components as substitutes for conventional metals or synthetic fibres, owing to their lightweight, biodegradable nature, low carbon emissions, renewable properties, and rapid growth cycle of raw materials. Consequently, the global market for bio-based composites is experiencing growth for reduce the greenhouse gases generated in industrial production. Composite structures typically require machining operations for assembly purposes using conventional drilling process. Conventional drilling is widely used for making holes in composite structures, but it poses some limitations related to accelerated tool wear, undesirable thermal effects, and respiratory hazards. An alternative is to use non-conventional drilling techniques that mitigate some or all the limitations. Abrasive water jet drilling can be an excellent candidate for drilling bio-based composites as it’s a thermal free machining process and non-contact machining to minimal damage to the surface and interior. Also, abrasive water jet drilling can reduce the burr in bio-base composites to reduce processing costs However, the hydrophilic nature of bio-based composites can influence the hole quality and overall performance of the machined part. Therefore, this work investigates the effect of abrasive water jet drilling parameters namely water pressure, traverse speed, and stand-off distance on the hole quality, kerf taper, geometrical tolerances, and open-hole tensile strength of flax laminates. The objective of the study is also to analyse the effects of drilling on hole quality and water absorption when the workpiece is positioned both below and above the water level in the tank. The experimental results were further analysed via statistical methods and analysis of variance (ANOVA). The borehole quality and presence of delamination and ply separations were further analysed using scanning electron microscopy (SEM) and micro computed tomography (Micro-CT). The results indicate that the AWJD parameters significantly affect the quality and geometrical tolerances of the hole. Digital image correlation (DIC) was employed to assess the quality of the hole when subjected to tensile loading and establish a relationship between the drilling parameters and the structural integrity of the machined component.