Kevlar and carbon fibres and fabrics have won a leading place in the structure market, although such materials are not cheap, and are increasingly used for reinforcing and strengthening structural elements in the civil engineering, automotive, aerospace and military industries, due to their superior mechanical properties, especially in terms of strength. The mechanical characteristics of such composite materials must be known in order to numerically simulate the mechanical behaviour of such structures in terms of the distribution of stresses and strains. It has also become a necessity to understand the effects of reinforcement with both types of fibres (carbon fibres and Kevlar fibres) on the mechanical properties, especially on the impact properties of such composites. This review aims to expose the main advantages and disadvantages of the hybridization of carbon and Kevlar fibres. For this reason, an overview is presented concerning the main characteristics (tensile strength, flexural strength, impact strength, coefficient of thermal expansion and so on) for carbon and Kevlar fibres and also for hybrid Kevlar–carbon composite materials to aid in the design of such hybrid composite materials. Finally, some civil construction rehabilitation and consolidation applications of the composites reinforced with carbon fibre, Kevlar fibre or with hybrid Kevlar–carbon fabrics are highlighted in the last part of the paper.

As hybrid carbon-aramid composites become widely used in various industries, it has become imperative to mechanically characterize them using accurate methods of measuring the entire deformation field such as the digital image correlation (DIC) method. The accuracy of the numerical simulation of carbon-aramid composite structures depends on the accuracy of the elastic constants. Therefore, the goal of this research is to model and simulate the mechanical behaviour of the composite based on epoxy resin reinforced with carbon-aramid woven fabric by considering the mechanical properties investigated by tensile test combined with DIC and the bending test. The curves of the transverse strains related to the longitudinal strains were investigated using DIC in order to determine the Poisson’s ratios in the case of tensile tests applied in warp or weft directions of the reinforcement fabric. The impact strength determined by Charpy tests is also reported. The other main objective is to use the analytical models to compute the tensile and flexural moduli of elasticity for the fictitious orthotropic materials which behave similarly to the carbon-aramid composite investigated. The simulations regarding the behaviour of the carbon-aramid composite in tensile and bending tests were validated by the experimental results, since the maximum errors recorded between experimental and theoretical results were 0.19% and 0.15% for the equivalent tensile modulus and for the equivalent flexural modulus, respectively.

The large-scale use of composite materials reinforced with carbon–aramid hybrid fabric in various outdoor applications, which ensures increased mechanical resistance including in impact loadings, led to the need to investigate the effects of aggressive environmental factors (moisture absorption, temperature, thermal cycles, ultra-violet rays) on the variation of their mechanical properties. Since the literature is still lacking in research on this topic, this article aims to compare the low-velocity impact behaviour of two carbon–aramid hybrid composite materials (with and without rubber core) and to investigate the effects of water absorption on impact properties. The main objectives of this research were as follows: (i) the investigation of the mechanical behavior in tests for two impact energies of 25 J and 50 J; (ii) comparison of the results obtained in terms of the force, displacement, velocity, and energy related to the time; (iii) analysis of the water absorption data; (iii) low-velocity impact testing of wet specimens after saturation; (iv) comparison between the impact behaviour of the wet specimens with that of the dried ones. One of the main findings was that for the wet specimens without rubber core, absorbed impact energy was 16% less than the one recorded for dried specimens at an impact energy of 50 J. The failure modes of the dried specimens without rubber core are breakage for both carbon and aramid fibres, matrix cracks, and delamination at matrix–fibre interfaces. The degradation for the wet specimens with rubber core is much more pronounced because the decrease in the absorbed impact energy was 53.26% after 10,513 h of immersion in water and all the layers were broken.