V. S. Mechandjieva and K. Z. Markov. Stress concentration around a hole in a micropolar solid with voids, Annuaire Univ. Sofia, Fac. Math. Méc., Livre 2 , 81/1987, 1993, pp. 85-104.

Abstract. The general solution of the plane problem in the micropolar-dilatation theory of elasticity is proposed. Such a theory describes a solid in which the fields of displacement, change of the volume (dilatation) and rotation are kinematically independent. The obtained solution is applied to the classical problem of stress concentration around a circular hole in an unbounded micropolar solid with continuously distributed set of voids which is modelled as micropolar-dilatation. An explicit formula for the stress concentration factor is derived which generalizes the earlier results of V. A. Palmov (in the micropolar case) and of S. Cowin (in the dilatation case)