The effect of Poisson's ratio and the far‐field boundary conditions on the accuracy of finite element calculations

It is shown that a finite element calculation which approximates an ‘infinite medium’; problem by a mesh with finite boundaries will yield greater accuracy when stress boundary conditions are applied on the far‐field boundary than is obtainable with displacement boundary conditions. In particular, with Poisson's ratio close to 0.5, the accuracy of the latter model is severely impaired, whereas the stress boundary condition model is unaffected for Poisson's ratio of 0.49 and a reasonable mesh. The eight‐node quadratic isoparametric element displays superb accuracy for the axisymmetric thick cylinder with either type of boundary condition.