INVESTIGATION OF END EFFECTS IN COMPOSITE LAMINATES

Abstract

In isotropic materials, the effect of exact distribution of an applied load or support conditions is apparent only in the near vicinity of the applied load. Hence, there effects are termed as end effects. End effects in isotropic materials have been traditionally ignored in the light of Saint-Venant's principle_ It has been established be many researchers that decay length for the end effects in fibre reinforced composite material may be much longer than the same for isotropic material and hence this phenomenon requires a fresh look. In present investigation the end effects in composite material have been investigated by a FEM analysis A standard tensile test specimen is taken and it is discretized into triangular elements . Parabolic loading is assumed at the ends and effect of material orthotropy parameters such as E1/E2 ratio and E1/G12 ratio and aspect ratio on the end effects have been investigated. A computer programme implementing the FEM scheme is used for evaluating stresses, strains and displacements at each node. It is observed that ratio E1/G12 haSe more effect on exact stress distribution and decay length as compared to the ratio E1/E2. It is also observed that with the increase of aspect ratio upto a limit, decay length reduces after which there is no significant effect of aspect ratio on end