BIFURCATION OF ORTHOTROPIC SOLIDS

We consider a large deformation plane-strain problem involving a compr essible orthotropic solid subjected to uniaxial compressive loading al ong one of the principle directions which is aligned with the boundary of a half-space. An exact solution for the displacement field is obta ined and a condition for the smallest compressive load corresponding t o the onset of a surface instability is determined. It is shown that w hen the compression occurs along the stiffest direction this condition is expressible in terms of a cubic polynomial, and that the correspon ding critical loan is lower than the well-known estimate which determi nes the critical load to be equal to the inplane shear modulus.