Effects of the Addition of the Inelastic Fibers on the Energy Dissipation in the Composite Cantilever Beam

Abstract

Present work deals with the analysis of the variation in the stresses of an inelastic composite cantilever beam. The cantilever beam is made up of four bi-directional symmetrically stacked glass-fiber/epoxy (GFRP) laminas. The stress field in the beam has been calculated using one dimensional finite element formulation of the Timoshenko beam theory. GFRP are the elastic composites and their behaviour is brittle. Thus the energy dissipation is generally given by the area under the elastic curve. The addition of the inelastic fibers in the composite extend this area after the yield stress leading to the more energy dissipation. To achieve an increase in the energy dissipation, aluminium (Al.) has been introduced as an inelastic fiber in the top-most layer and is considered to undergo kinematic hardening. Finite element formulation has been done for the aluminium reinforced glass fiber/epoxy composite cantilever beam. At small loads, even an incremental increase in the plastic area can be beneficial. The overall stiffness of the top-most layer is calculated by the rules of mixtures (Voigt) method and updated once stresses reach in the inelastic zone. As the top and the bottom most layer is made up of same composite material but the only difference is that of inelastic fibers in the top most layer, we can compare the stresses and how much energy dissipation increases in the top-most layer. The effect of varying the thickness on the stresses and energy dissipation is discussed.