Thin–Walled Structures 158 (2021) 107150 Available online 10 October 2020 0263-8231/© 2020 Published by Elsevier Ltd. A review of properties and fabrication techniques of fber reinforced polymer nanocomposites subjected to simulated accidental ballistic impact Usaid Ahmed Shakil a, b , Shukur Bin Abu Hassan a, b, * , Mohd Yazid Yahya a, b , Mujiyono c , Didik Nurhadiyanto c a School of Mechanical Engineering, Universiti Teknologi Malaysia, 81310, Johor Bahru, Malaysia b Centre For Advanced Composite Materials (CACM), Universiti Teknologi Malaysia, 81310, Johor Bahru, Malaysia c Department of Mechanical Engineering Education, Universitas Negeri Yogyakarta, 55281, Yogyakarta, Indonesia A R T I C L E INFO Keywords: Ballistic impact Nanoparticles Energy absorption Ballistic limit velocity Nanocomposites ABSTRACT Composite structure experience ballistic or high velocity impact loading during in-fight operations owing to hail, bird and debris strike. In thin laminates, such an impact entails damage resulting from complex interplay of projectile characteristics, composite material properties and environmental conditions. Delamination resistance and energy absorption are two parameters to characterize the ballistic performance of materials in research community. As out of plane properties are controlled by matrix, its microstructural modifcation is the primary method through which ballistic performance of composites are sought to be improved. High specifc surface area nanoparticles are now being used, for matrix modifcation, to induce nano-scale toughness mechanisms. This paper starts with brief outline of these mechanisms followed by summarizing nanocomposite fabrication tech- niques and ballistic impact performance of nanocly, graphene, carbon nanotube and other miscellaneous nanoparticle reinforced composites. Finally, it highlights unexplored areas in polymer nanocomposite research with focus on ballistic performance. 1. Introduction Continuous fber reinforced composites are prized as materials of construction in aircraft industry because of their high specifc strength, modulus and corrosion resistant [1]. In this sector, stringent safety regulations and in-service mechanical requirements lay emphasis on reliability and durability of materials. For instance, industry must comply with fre-retardance and crashworthiness standards, and these need to be considered from material design point of view. Although, composite materials offer versatility and high degree of optimization in design, inherent weaknesses like poor out of plane properties and weaker interfaces mar the prospect of their usage in structural frame [2]. Composites are susceptible to impact damage owing to runway debris or hail strike during fight that may vary in severity depending upon the strain rate [3–6]. A report prepared by German aerospace center shows that majority of these impact events occur in 50–300 m/s range [7]. The extent of damage depends on other factors too such as: (i) projectile geometry (ii) target profle (iii) projectile mass and shape [8,9]. A characteristic failure in such cases is called delamination that drastically decreases load bearing capacity of structure under the effect of repeated loading cycles. Out of plane properties of these composites have been identifed to be dominated by matrix properties. As the primary target of projectile is matrix, incipient defects occur in matrix that eventually retards com- posite’s capability to transfer load to fbers. Performance critical prop- erty, here, is toughness that controls both energy absorption and delamination resistance of composites. Variety of methods have been opted to maximize the toughness of composites, predominantly through matrix modifcations, including thermoplastic phases [10–13], fabric architecture [14–17] hybridization [18–22]and nanoparticle addition [23,24]. Usage of polymer nanocomposites as building block of aircraft structures, although, is in genesis stage but their potential in future aircraft structures has been realized [25]. For instance, Lockhead Martin announced replacement of wingtip fairings material with CNT rein- forced epoxy for F-35 Lightning II aircraft and stated that currently there is no hurdle in incorporating these materials for structural applications except to avoid certifcations [26]. Studies have been done in anticipa- tion of such a usage to confrm the potential of fber reinforced * Corresponding author. Centre for Advanced Composite Materials (CACM), Universiti Teknologi Malaysia, 81310, Johor Bahru, Malaysia. E-mail address: shukur@utm.my (S.B. Abu Hassan). Contents lists available at ScienceDirect Thin-Walled Structures journal homepage: http://www.elsevier.com/locate/tws https://doi.org/10.1016/j.tws.2020.107150 Received 6 May 2020; Received in revised form 15 August 2020; Accepted 12 September 2020