Contents lists available at ScienceDirect Wear journal homepage: www.elsevier.com/locate/wear A multiple particle impact model for prediction of erosion in carbon-fiber reinforced composites Ajaz Ahmed Deliwala, M. Rinu Peter, Chandra Sekher Yerramalli ⁎ Aerospace Engineering Department, IIT Bombay, Powai, Mumbai 400076, India ARTICLE INFO Keywords: Fiber reinforced composites Particle size Numerical modelling Solid particle erosion ABSTRACT Material loss and degradation due to erosion remains a major concern in engineering applications for composite materials. A finite element based model has been developed to predict the erosion behavior of unidirectional carbon fiber-epoxy (CFRP) composites subjected to solid particle impacts. In this model, the CFRP plate is subjected to multiple particle impacts at a velocity of 45 m/s, with steel balls as the erodent particles. The Influence of impact angle, erodent particle stream orientation (parallel and transverse to the fiber direction) and erodent particle size has been studied by varying the impact angle from 15⁰–90⁰ and particle sizes considered are of radii 150 μm, 200 μm and 250 μm. The model captures the influence of the erodent particle to particle impacts and the target surface properties by defining two new ratios, kinetic energy ratio, “η k ” and substrate surface property ratio, “η s ”. The cumulative eroded mass predictions are higher for transverse to fiber impact as com- pared to parallel to fiber impacts. It is also observed that as the erodent size increases the total eroded mass loss increases at all impact angles. The eroded mass predictions obtained from the numerical model compare fa- vorably with the eroded mass results obtained from experimental data reported in the literature. 1. Introduction Erosion is a process of material degradation and is one of the major causes of wear in structural materials. Degradation due to erosion is an issue for all materials, but it is more severe in the case of polymer composite materials [1]. Helicopter rotor blades and wind turbine blades made of polymer composite materials are prone to erosion da- mage due to solid particle and/or water droplet impact during opera- tion. This results in the increased surface roughness of the blade af- fecting the aerodynamic efficiency [2,3]. Leading edge erosion in wind turbine blades leads to increased vibrations in the blade causing da- mage to the turbine bearings [3]. Thus, a better understanding of the mechanics of erosion in polymer composites would be useful in the estimation of erosion rates under different types of environments and in designing erosion resistant surfaces. During the past few decades, a lot of research has been done on erosion of conventional materials in the form of experimental [4–7], numerical [8–14] and mathematical [15–21] models. But only a few researchers have taken into account the erosion in fiber reinforced composites. A recent review done by Kaundal [22] discusses the role of process variables on erosion of polymer composites and lists various prediction models used to quantify erosion in polymeric composites. The author describes in detail the different models like experimental models [23–32], analytical models [33–35], models based on averaging rules [36,37], Taguchi method based models [34,38,39] and the Arti- ficial neural network (ANN) based model [40] to predict the erosion of polymer composites. Zahavi and Schmitt [23] conducted experiments on glass-epoxy composites which showed higher erosion resistance than other com- posite materials. Roy et al. [24] conducted experiments to evaluate the erosion behavior of GFRP composites with different matrix materials, they observed ductile behavior in thermoplastic matrix and brittle be- havior in thermoset matrix, epoxy matrix showed better erosion re- sistance. Investigations carried out by Barkoula and Karger-Kocsis [30] on solid particle erosion of glass fiber (GF) epoxy (EP) composites showed that there is a large dependence on the impact angle of solid particles, they showed that GF/EP composite behaved in a brittle manner with maximum eroded mass occurring at 90 degrees impact angle. GF/EP composite with higher interfacial shear strength had better erosion resistance when compared with poorly bonded GF/EP composites. A critical review done by Miyazaki [41] summarizes the effect of volume fraction, material and orientation of fiber reinforce- ment on solid particle erosion of composites. Also, the effect of inter- facial strength between the fiber reinforcement and matrix was con- sidered by Miyazaki [32,41]. Sundararajan and Manish [42] introduced a new parameter ‘erosion https://doi.org/10.1016/j.wear.2018.04.014 Received 19 December 2017; Received in revised form 13 March 2018; Accepted 24 April 2018 ⁎ Corresponding author. E-mail addresses: ajazahmed.r@aero.iitb.ac.in (A.A. Deliwala), rinupeter@gmail.com (M.R. Peter), chandra@aero.iitb.ac.in (C.S. Yerramalli). Wear 406–407 (2018) 185–193 Available online 26 April 2018 0043-1648/ © 2018 Elsevier B.V. All rights reserved. T