Effect of hole position and stacking sequence on tensile and buckling behaviour of carbon/basalt epoxy composite laminate

Fibre-reinforced composites are gaining extensive utilisation across various industries, including automotive, Aerospace, Civil engineering, and other fields. The favourable attributes, such as their exceptional specific strength and stiffness, make them the preferred choice for numerous aircraft structural components, including the cockpit, wings, and empennage. However, it’s worth noting that the drilled holes used for composite joints represent a significant vulnerability and are a primary cause of structural failure in aircraft structures. This study systematically investigates the influence of circular hole configuration and fiber stacking sequence on the mechanical performance of carbon/basalt hybrid epoxy composite laminates under tensile and buckling loads. Composite laminates with varying carbon/basalt ratios were fabricated using hand lay-up technique. Specimens featuring different circular hole configurations (no hole, single hole, two horizontal holes, and two vertical holes) were subjected to tensile and buckling tests following ASTM D3039 and ASTM E2954 standards, respectively. Fracture morphology was examined using Field Emission Scanning Electron Microscopy (FESEM). The output of the experiments demonstrated that hole configuration significantly affects mechanical properties. For tensile loading, specimens with side-by-side holes exhibited the lowest strength retention (approximately 30–40% reduction), while top-and-bottom hole configurations showed moderate strength reduction (20–25%). Conversely, under buckling loads, side-by-side configurations demonstrated superior performance compared to top-and-bottom arrangements. The hybrid composite CB2 (C3B6C3) exhibited optimal performance, achieving 87% of pure carbon composite strength while demonstrating enhanced damage tolerance. The study reveals that hole arrangement and stacking sequence critically influence the load-bearing capacity of hybrid composites.