Abstract: A study of drilling-induced damage in barely visible impact damaged (BVID) carbon fibre reinforced polymer (CFRP) laminates where small circular holes were intentionally drilled into the impacted zone as an intermediate step of the resin-injection repair process was reported. The pristine CFRP laminates were quasi-statically indented to yield damage that were barely visible. Following the drilling of open/blind, single and binary holes in the impacted laminates at selective locations within the BVID zone, the holed laminates were subjected to in-plane compression test until they broke apart. Binary-hole specimens at fixed distance apart were tested in parallel/normal to the external load. Statistical analysis was used to assess for diminution of laminate mechanical properties contributed by hole-hole interaction and hole-hole orientation effects. BVID specimens showed significant diminution of property value (compared to pristine ones). No dependence of mechanical properties on hole-hole orientation was observed. Owing to the large hole-hole separation, this significantly mitigated the hole-hole interactions. Finally single/binary-hole BVID laminates revealed laminate stiffening effects: the stiffness was significantly higher than that of undrilled BVID specimens.

Biography: Kheng Lim Goh is a Fellow of the Institute of Mechanical Engineers (UK), Chartered Engineer and Chartered Physicist with the Institute of Mechanical Engineers (UK) and Institute of Physics (UK) respectively. His research interest is in the repair of fibre reinforced composites used in aerospace and automotive engineering. He holds the position of Associate Professor (Reader in Mechanics of Composite Materials) at Newcastle Research and Innovation Institute (NewRIIS) and the Newcastle University in Singapore, and is affiliated to the Faculty of Science, Agriculture & Engineering, Newcastle University (UK). He leads the Advanced Composites Research (ACR) Group at NewRIIS. Professor Goh has authored and co-authored over 80 papers in peer-reviewed journals, books and conferences that cover a wide range of composite materials, together with international collaborators from Argentina, Canada, India, Malaysia, Singapore, Sri Lanka and UK. His research theme underlies an understanding of the physical properties of natural and synthetic materials and implications for designing composites for engineering applications and for repairing damaged composites. He is the author of an authoritative book on 'Discontinuous-fibre reinforced composites: fundamentals of stress transfer and fracture mechanics' published by Springer.