Advanced composites are widely used in primary and secondary structural applications, for example, aerospace, automotive, marine, and renewable energy sectors. But it is well recognized that the impact resistance and damage tolerance of composite laminates are in general poor, which is a major challenge for optimizing structural designs. In this regard, an experimental study is conducted for enhancing the damage tolerance of 2D woven composite laminates by exploring yarn‐level fiber hybridization. Hybrid yarns are produced by combing high‐strength fibers, that is, S‐glass, and high‐toughness fibers, that is, polypropylene [PP], and using commingling and core‐wrapping processes. Using the hybrid yarns, 2D fabrics, that is, with 5H satin, 2/2 twill, and 2/2 basket architectures, are weaved, and subsequently hybrid S‐glass/PP/epoxy laminates are manufactured via vacuum assisted resin infusion. The low velocity impact response and energy absorption of the hybrid laminates are investigated by drop‐weight impact tests at different energy levels, that is, 15 J, 25 J, 35 J, and 50 J. The damage tolerance is studied by compression‐after‐impact (CAI) tests, measuring the residual compressive strength of the damaged laminates. Furthermore, the failure modes are investigated using scanning electron microscopy for identifying damage mechanisms in the hybrid laminates after the impact and CAI tests. The impact response and damage tolerance of the 5H satin, 2/2 twill, and 2/2 basket fabric laminates are compared with that of noncrimp‐fabric laminates produced with (ie, S‐glass/PP yarns) and without (ie, S‐glass yarns) yarn‐level hybridization. It is shown that yarn‐level hybridization and fiber architecture significantly affect the impact behavior and damage tolerance of the 2D woven S‐glass/PP/epoxy hybrid laminates investigated. The microscopy studies show that intra‐yarn, inter‐yarn, inter‐lamina failure mechanisms can in general be introduced by combining yarn‐level fiber hybridization and fiber architecture for modifying failure and energy dissipation mechanisms under low velocity impact and hence the damage tolerance of composite laminates.

Towards balancing in-plane mechanical properties and impact damage tolerance of composite laminates using quasi-UD woven fabrics with hybrid warp yarns. Composite Structures, 225, [111083].

Advanced composite materials are widely used in civil and military applications due to their superior specific strength and stiffness. However, they are susceptible to damage during impact loading. In order to improve the impact performance, yarn hybridisation and fibre architecture have been investigated in this study in order to evaluate their influence on the damage tolerance (i.e. post- impact flexural strength) of glass composite laminates. Two types of yarn have been used here, namely, pure glass yarns as a bench-mark and hybrid yarns (glass-polypropylene) to manufacture non-crimp and woven (twill and satin) fabric composites. The composite laminates were then subjected to low-velocity impact tests at various impact energies. Afterwards, post- impact flexural strength has been evaluated with a four-point bending test. It has been observed that the non-crimp and woven hybrid composites laminates displayed smaller damage areas compared to the non-crimp glass composites laminates. In addition, although the hybrid laminates have exhibited lower flexural strength properties than the non-crimp glass laminates, the former has shown higher post-impact flexural strength. Fractography analysis has suggested here that the damage failure modes such as intra-yarn cracks have been produced in the hybrid yarns laminates and intra-yarn and inter-yarn cracks have been produced in hybrid fabric laminates. These damage failures have contributed for absorbing impact energy leading to an enhancement of the damage tolerance of the hybrid laminates.

In the present work, impact and post-impact response of thermoset composite laminates manufactured from glass, flax, jute fabrics and their hybrid combinations (glass/ jute and glass/flax) made with various stacking sequences was studied. The low-velocity impact response of these laminates was investigated by drop-weight impact tests at different energy levels (20-50 J). Additionally, their post-impact behaviour was studied by compression after impact tests, measuring their residual compressive strength. Impact test results showed that glass composites had higher impact resistance than natural and hybrid composites. Moreover, the hybrid composites with glass fabric layers in the exterior resulted in better impact resistance compared to composites where glass fabric layers were placed in the interior with flax or jute fabrics. It was also observed that natural and hybrid composites absorbed more energy than that of glass composites between 20 and 40 J. Glass composites exhibited higher compression

Advanced composite laminates (i.e. glass composite laminates) are highly susceptible to low velocity impact, and the induced damage failures substantially reduced their residual mechanical properties and safe-service life during their application. Therefore, experiments and simulation efforts to predict their low-velocity impact damages and energy absorbing have significant importance in composite structures design. In this regards, experimental and finite element analysis (FEA) with aiding Abaqus software were respectively performed to investigate the influence of yarn hybridisation on the response of composite laminates under low velocity impact. The hybrid yarns, which consisted of S-glass and polypropylene yarns have been used to manufacture two types of composites; non-crimp cross-ply hybrid yarns and twill hybrid fabric composites. Additionally, for comparison, the non-crimp cross-ply and twill fabric composite laminates have been made from glass fibres only. The vacuum infusion resin process has been adopted to manufacture these composite laminates. The impact performance of composite laminates has been investigated using low-velocity impact at 15 J, 35, and 50 impact energy levels. The numerical analysis was executed using Abaqus/Explicit and Hashin failure criteria and continuum damage mechanics by using homogenous shell were adopted to simulate the intra-laminar damage in layers. Meanwhile, standard cohesive inter-laminar interfaces that inserted between composite layers with quadratic stress failure criteria have been used to model delamination failures. The numerical results regarding impact force-time, displacement–time and energy-time histories plots, as well as the damage evolution behaviour of matrix crack and fibre fracture, presented an agreement with experimental results.