Stress intensity factor using finite element analysis in rectangular orthotropic composite annular disk

The quadratic isoparametric elements which embody the inverse squareroot singularity were used to determine the stress intensity factor in an annular disk made of Boron-Epoxy composite material The displacements and stresses were determined in a rectangular orthotropic composite annular disk using isoparametric finite elements. The singularity in the strain field was provided by means of 8-noded isoparametric elements (4-nodes at the four corners and four mid-side nodes each at 1/4(th) distance from the edge). The results were obtained for various material properties and fibre orientation. The geometry of the annular disk was reported when subjected to a boundary radial and tangential load. The r singularity was provided at the boundary of the circular hole and the rest of the annular disk was modelled with ordinary isoparametric elements. The apparent stress intensity factor (K-I = sigma root r) was computed from the stress data near the circular hole, when it was subjected to uniform tension. A curve was drawn for apparent stress intensity factor versus the distance from the crack edge and was extrapolated to r = 0, the actual stress intensity factor was found on the y-axis.