A gradient micropolar elasticity scheme was proposed which was based upon the first gradients of distortion and bend-twist tensors for an isotropic micropolar medium. This was an extension of the theory of micropolar elasticity with couple stresses; combined with gradient elasticity in such a way that, in addition to hyper-stresses, hyper couple-stresses also appeared. The strain-energy, as well as depending upon the distortion and bend-twist terms of a micropolar medium (Cosserat continuum), also depended upon distortion and bend-twist gradients. By using a simplified version of this gradient theory, it could be linked to Eringen’s non-local micropolar elasticity. It was used to study a screw dislocation in gradient micropolar elasticity. An important result was that non-singular expressions were obtained for the force and couple stresses. The components of the force stress had maximum values near to the dislocation line, while those of the couple stress took maximum values at the dislocation line.

Defects in Gradient Micropolar Elasticity – I. Screw Dislocation. M.Lazar, G.A.Maugin: Journal of the Mechanics and Physics of Solids, 2004, 52[10], 2263-84