Finite Element Analysis of Low Velocity Impact on Woven Type GFRP Composite Laminates

In this work, numerical investigation isperformed to study the behaviour of a composite laminates under low velocity impact. Woven type Glass Fibre Reinforced Polymer [GFRP] composite plates having two different thicknesses of 2 mm and 4 mm has been considered, the specimens were subjected to low velocity impact at different velocities and the impact simulation has been performed on composite plate using explicit finite element analysis software LS-DYNA. Finite element simulation has been done to calculate impact energy and maximum impact force on the laminated composite plates. Various parametric studies are performed includes boundary conditions, thickness of the laminates, lay-up sequence, mass and velocity of the impactor on the composite plate. An attempt also made to calculate the impact energy and maximum impact force using analytical methods to validate the numerical predictions. Keywords— Boundary conditions, Laminate, Mass, Velocity, Impactor, lay-up sequence, LS-DYNA and Impact energy. INTRODUCTION A composite material is a macroscopic combination of two or more distinct materials, having a recognizable interface between them. Composite laminate is a combination of fiber and resin mixed in proper form. One of the unique properties of composite laminate is that, it has high specific strength. Composites are being utilized instead of metallic materials in structures where weight is a major consideration, example aerospace structures, high speed boats and trains [1]. The use of composites has evolved commonly to incorporate a structural fiber and plastic, this is known as Fiber Reinforced Plastics (FRP). Fibers provides structure and strength to the composite, while a plastic polymers holds the fiber together, common types of fibers used in FRP composite includes: Glass fiber, Aramid fiber, Carbon fiber, Boron fiber, Basalt fiber, Natural fiber etc., in case of fiber glass, thousands of tiny glass fibers are compiled together and held rigidly in place by plastic polymer resin. Common plastic resins used in composites includes: Epoxy, Polyester, Vinyl ester, Polyurethane and Polypropylene etc. Impact is defined as “the striking of one component against another with force instantly”; it involves the collision of two bodies: the impactor and the target. During collision, an impactor indents the target and makes indentation on the plate. The knowledge of dynamic response of structure and its damage resistance is much needed to optimize the structure requiring high safety like aircraft structural applications. The majority of impact test has been carried out on a flat plate with either simply supported or clamped boundaries. The inability to visualize the internal damage of composites makes the research community to focus on the low-velocity impact phenomena stringently. Impact phenomenon is a very complicated process in which the performance depends on many parameters like duration of the impact, kinetic energy, velocity of the impactor, properties of target and the impactor materials [2]. The experimental analysis is often used to study loading, deformation and damage of composite plates. However, this method is expensive, time consuming, and requires multiple standardized test prototypes, equipment, and strongly regulated test settings [3]. A significant advantage of finite element analysis is that an advanced preliminary study can be carried out by using a virtual prototype in a virtual environment which can substantially cut costs, reduce the development time and substantially optimize the overall development process. The main objective of this paper is to investigate the behaviour of the composite plate under three different velocities by using finite element analysis software LS-DYNA. An analysis result has been compared against available experimental results from the literature survey [4]. ANALYTICAL PROCEDURE The Mathematical model used for present work from reference [5] is used to find maximum impact force and impact energy at different velocities is given by the equations (1) and (2) respectively. 1 2 mi vi 2 = 1 2 Fmax 2