Demonstration of pseudo-ductility in unidirectional hybrid composites made of discontinuous carbon/epoxy and continuous glass/epoxy plies

Abstract

A new, partially discontinuous architecture is proposed to improve the mechanical performance of pseudo-ductile, unidirectional (UD) interlayer carbon/glass hybrid composites. The concept was successfully demonstrated in different laminates with high strength and high modulus carbon and S-glass epoxy UD prepregs. The novel hybrid architecture provided pseudo-ductile tensile stress-strain responses with a linear initial part followed by a wide plateau and a second linear part, all connected by smooth transitions. The best hybrid configuration showed 60% improvement in modulus compared to pure glass, 860 MPa plateau stress and 2% pseudo-ductile strain. The initial modulus, the plateau stress and the overall tensile stress-strain response of each specimen configuration were predicted accurately

Novel experimental procedure and determination of full displacement fields of delaminating composite layer interfaces for evaluation of the mode II cohesive law

“…The materials considered for specimen design, and applied for the experiments were selected to be consistent with the authors' previous studies [18,[43][44][45][46] and because of high mismatch between the stiffness of the carbon and glass layers, which is useful for stabilising the stress in the plateau region of the stress-strain curve. Furthermore glass/carbon hybrid composites are widespread and their delamination behaviour is of high interest to the scientific community.…”

“…The discontinuous central layer UD specimens with continuous outer layers which can take the full load after delamination initiation furthermore assures stable propagation of mode II interlaminar cracks, allowing for image acquisition. Similar cut central layer but glass/carbon interlayer hybrid specimens, which show stable central layer pull-out, were used earlier by Czél et al [44] to study the mode II fracture toughness of hybrid composite interfaces. This layer-by-layer hybrid specimen type with a cut central carbon/epoxy and continuous outer glass/epoxy layers was a good starting point for the development of similar architecture but different size specimens suitable for in-situ testing in a SEM chamber.…”

Modelling hybrid effects on the stiffness of aligned discontinuous composites with hybrid fibre-types

“…with intimate intermingling of fibre-types), and extends further the ability to tailor the properties of composites in terms of stiffness, strength or toughness [1][2][3]. Hybrid discontinuous composites have already been manufactured [2][3][4][5] and confirmed the advantages listed previously; however, "hybrid effects" can be observed in the experimental data of hybrid discontinuous composites, not only in the measured strength and failure strain, but also on the stiffness [2][3][4]6].…”

Effects of Laminate Arrangement on the Failure Behaviour of Hybrid Composite Plates under Transverse Sinusoidal Load

“…Laminated composite materials are oriented in directions that will improve the strength in the primary load direction [3]. Hybridisation, or creating a ply-by-ply hybrid structure is also utilized to improve the common composites failure mode by making it more gradual and distributed [5]. This is done to counteract the failure mode of composites that are usually unexpected and instantaneous, with absolutely no warning as well as low residual load bearing capacity [5].…”