Abstract

In the coming years, the growth of aircraft fleets is expected due to increased globalization and transportation needs, leading to a rise in the use of CFRP (Carbon Fiber Reinforced Polymer) composites thanks to their excellent specific properties. This implies that the sector must face the challenge of dealing with CFRP elements from aircraft that have reached the end of their useful life, without a clear and sustainable alternative to landfill disposal currently available. On the other hand, the rehabilitation of buildings and civil infrastructure is essential to prolong their useful life and reduce energy consumption and environmental impact associated with construction. Currently, there are various techniques for using CFRP composites to reinforce reinforced concrete structures, improving their flexural response. However, the manufacturing cost of these reinforcement materials and the associated environmental cost limit their wider use. Therefore, the reuse of CFRP composites from other sectors can represent a very interesting alternative. This work explores the possibility of using CFRP elements from the aerospace sector to reinforce reinforced concrete structures. Specifically, the capacity of these reused CFRP composites to be used as external reinforcement in concrete beams subjected to bending is analyzed. The results are compared with those of a reference beam reinforced with newly manufactured CFRP composite material. It is concluded that it is feasible to reuse CFRP materials from the aerospace sector for the reinforcement of reinforced concrete beams.

Abstract

Fibre breakeage in composite materials is usually a determining damage mechanism for its structural integrity due to the high energy associated, in comparison with matrix cracking. For this reason, the assessment of the translaminar fracture toughness is relevant for accurate numerical predictions of composite structures. However, there are scarce investigations related to this topic for additive manufactured composites reinforced with continuous fibres.  In this investigation, the translaminar fracture toughness of 3D-printed continuous fibre reinforced polymer (c-CFRP) composites was characterised using double-tapered compact tension (2TCT) specimens. The 2TCT geometric dimensions were obtained through a parametric study to prevent undesired failure modes. The results show a translaminar fracture toughness of 17.4 N/mm for the tested 0/90 laminates. The fracture toughness corresponding to the tensile failure of the 0° ply was derived using a rule-of-mixtures approach. Post-mortem micrographic and X-ray analysis indicated the presence of fibre pull-outs in the crack surface and confirmed the absence of any additional damage, validating the use of 2TCT geometry for the determination of the translaminar fracture toughness in additively manufactured c-CFRP composites.