STRESS-CONCENTRATION FACTORS FOR FINITE ORTHOTROPIC LAMINATES WITH A CIRCULAR HOLE AND UNIAXIAL LOADING.

Stresses were calculated for finite-width orthotropic laminates with a circular hole and remote uniaxial loading using a two-dimensional finite-element analysis with both uniform stress and uniform displacement boundary conditions. Five different laminates were analyzed: quasi-isotropic left bracket 0 degree / plus or minus 45 degree /90 degree right bracket //s, 0 degree , 90 degree , left bracket 0 degree /90 degree right bracket //s, and left bracket plus or minus 45 degree right bracket //s. Computed results are presented for selected combinations of hole-diameter - sheet-width ratio d/w and length-to-width ratio L/w. For small L/w values, the stress-concentration factors K//t//n were significantly different for the uniform stress and uniform displacement boundary conditions. Typically, for the uniform stress condition, the K//t//n values were much larger than for the infinite-strip reference condition; however, for the uniform displacement condition, they were only slightly smaller than for this reference. The results for long strips are also presented as width-correction factors. For d/w less than equivalent to 0. 33, these width-correction factors are nearly equal for all five laminates.