This paper introduces new composite architectures using carbon and glass fibre-reinforced epoxy prepregs to achieve gradual failure under bending. The concept is based on a technique developed by the authors to design hybrid composites with gradual failure in tension combined with beam theory to identify and control the failure sequence of the plies in the layups. Two layups are designed based on standard ply thickness S-Glass and hybrid sub-laminates made out of intermediate and high modulus thin-ply carbon prepregs. The layups are tested under 4-point bending loading where a gradual failure alongside high values of flexural displacement are achieved. No catastrophic failure is observed throughout the whole loading process. The gradual layer-by-layer failure of the surface layers on the tensile side produces a brush-like appearance. Microscopy observations from interrupted tests verified fragmentation of the high-modulus carbon layer followed by gradual failure of the intermediate modulus carbon layer and delamination on the tensile side, as well as stable shear cracks of the high-modulus carbon layer on the compression side.
Bibliographical noteFunding Information:
The authors acknowledge the financial supports provided by the Royal Academy of Engineering and the Newton Fund : Industry-Academia Partnership Programme, IAPP1/100149 as well as the UK Engineering and Physical Sciences Research Council (EPSRC) Programme Grant EP/I02946X/1 on High-Performance Ductile Composite Technology in collaboration with Imperial College, London. Author G. Idarraga would like to thanks Colciencias of the Colombian government for the Doctoral grant, Colciencias, call 647, Sapiencia of the municipality of Medellín for the funding call Enlaza-Mundos programme 2017 and The National University of Colombia. The authors would like also acknowledge and thank Mr Ellis Hills for initial Matlab code developments, Mrs Fatemeh Jalalvand for editing the photo in Fig. 9 and Dr. Alessia Prato for her support in the manufacture of the layups.
© 2021 The Authors
- hybrid composites
- gradual failure
- fragmentation and delamination