FINITE ELEMENT MODEL FOR THE ANALYSIS OF LAMINATED FRP. COMPOSITE PLATES UNDER IMPACT LOADING

Abstract

In modern civil engineering structures laminated FRP (Fiber Reinforced Polymer or Plastic) composite is widely used in various applications including roof of buildings, bridge decks, structural panels and beams. Using the laminated composite material in construction introduces many advantages such as high strength/stiffness to weight ratio, survivability in extreme weather conditions, durability, fatigue resistance, and design flexibility (three-dimensional forms molded in place), easy to install in structure replacement. The behavior of composite laminates under impact loading is very complex phenomenon because many concurrent modes are observed during the failure of composite laminate under impact. Fiber breakage, delaminations, matrix cracking, large displacements and brittle failure are some effects, which should be considered when a structure made from composite material is impacted by a foreign object. Graphite epoxy composites generally used in construction lack effective mechanisms for absorbing local impact energy often resulting in penetration and a structural strength reduction. Composite laminate may also be affected due to low velocity impact. Matrix cracking and delamination are the most common damage mechanisms in laminated fiber reinforced composites due to low velocity impact. Such damage is very difficult to detect by naked eye. This invisible damage may cause serious decrease in material strength and stiffness, which can be created during production, repair and maintenance and small particle crashes to composite body. In this study, Finite element code, ABAQUS is used to analyse the behavior of laminated composite plates under incident impact. It has ability to model progressive damage and failure of composites in Abacius/Explicit with a general, user-defined material capability. An approach to predict the initiation of damage and perforation in composite laminated plates is brought forward in this analysis. Hashin (1990) and Puck et al. (1998) material models are implemented by VUMAT (User Material Subroutine) into ABAQUS/Explicit, in order to simulate the failure mechanisms of laminated composite plate. The influences of different velocities and thicknesses of plates are investigated in the form of contact force—time histories, displacement—time histories, energy-time histories and stresses-time histories. The ballistic velocity and residual velocity of graphite-epoxy composite material for different boundary conditions, ply orientations and friction coefficients are also determined.