Technical Report Statistical effects of using ceramic particles in glass fibre reinforced composites Anine Cristina Detomi a , Reniene Maria dos Santos a , Sergio Luiz Moni Ribeiro Filho a , Carolina Coelho Martuscelli a , Túlio Hallak Panzera a,⇑ , Fabrizio Scarpa b a Department of Mechanical Engineering, Federal University of São João del Rei (UFSJ), Praça Frei Orlando n 170, Centro, 36.307-352, São João Del Rei, Brazil b Advanced Composites Centre for Innovation and Science, University of Bristol, UK article info Article history: Received 18 October 2012 Accepted 10 September 2013 Available online 18 September 2013 abstract The paper describes the influence provided by micro-ceramic particles on the flexural behaviour of glass- fibre composites. A full factorial design on 128 composites samples has been performed to identify the effect of the location, weight fraction and type of particles over the bulk density, flexural strength and modulus of glass fibre composites. A microstructural analysis was performed to evaluate the crack prop- agation mechanism of reinforced laminate composites under three bending testing. An arbitrary- Lagrangian–Eulerian based finite element analysis was used to assess the effect of ceramic particle loca- tion on the flexural properties. The study identifies the use of 10 wt% of silica microparticles in the upper side of the sample as the best micromechanical configuration to obtain the highest mechanical perfor- mance in the composites. Ó 2013 Elsevier Ltd. All rights reserved. 1. Introduction The use of nanoparticles as third phase in classical reinforced polymeric composites has attracted substantial interest in recent years, because of the advances in terms of manufacturing and cost reduction offered by modern nanotechnologies [1]. Particular emphasis has been placed on using ceramic particles in epoxy re- sin/glass fibre composites [2–11] to combat the brittleness and poor fracture toughness behaviour of epoxy matrices. The addition of particles into thermoset polymer has been demonstrated to pro- vide an effective enhancement of the strength and toughness of composite materials [12]. Silica, alumina and glass particles have been used as filler, and epoxy–silica based composites are widely used in the electronics, automotive and aerospace industries to dis- sipate heat and prevent electrostatic accumulation [13]. The inter- action of the fillers with the composite matrix is particularly important when irreversible or energy dissipation processes are active, as in the case of plastic deformation and fracture. The par- ticle addition tends in general to increase the stiffness of the ma- trix, leading to the enhancement of the Young’s modulus [2,3–6], toughness [2,5,6], tensile [3] and flexural strength [7]. Other prop- erties that exhibit a remarkable improvement when using particles as third phase are the compressive strength [8,9], impact strength [3,10] and glass transition temperature [7], in addition to improve the fibre–matrix interface conditions [10] especially at high tem- peratures [2]. Particle size and weight fraction for matrix reinforce- ment are selected to provide specific properties for the composite material [14]. In general, the inclusion of nanoparticles into epoxy-based fibre reinforced composites is confined to small weight fractions (less than 5 wt%) [2,3–8]. Silica nanoparticles, on the opposite, have been used with weight fractions ranging from 15 wt% [15,16] to 30 wt% [9] to enhance the compressive loading performance of hybrid composites, as well as the energy absorp- tion during impact, fatigue resistance to cyclic loading and lower the thermal expansion coefficient. The addition of SiC particles provides also an increase of the wear resistance without significant change in specific weight [17–19]. However, particles clustering can contribute significantly to the deterioration of the mechanical properties in composite materials [20–24]. The mechanical properties of the glass fibre reinforced compos- ite can be improved by adding high stiff particles. The ceramic par- ticles are able to provide the mechanical interlocking at the fibre– matrix boundary, because of promoted bonding forces between glass fibre and the ceramic particles-modified matrix [9,25]. Sup- pressed matrix cracking and reduced crack propagation rate in the nanoparticle-modified matrix were also observed to contribute towards the enhanced tensile fatigue life of the glass fibre rein- forced composite employing silica nanoparticle- modified epoxy matrix [23]. Moreover, under flexural loading failure can be inter- preted as combination of tension and compression effects [26]. Ref. [26] describes in particular carbon fibre reinforced composites investigated under three point bending loading, during which the 0261-3069/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.matdes.2013.09.026 ⇑ Corresponding author. Tel.: +55 (32)33792603. E-mail address: panzera@ufsj.edu.br (T.H. Panzera). Materials and Design 55 (2014) 463–470 Contents lists available at ScienceDirect Materials and Design journal homepage: www.elsevier.com/locate/matdes