A plane dynamic axisymmetric problem for a hollow cylinder

A dynamic problem for an elastic hollow cylinder whose surfaces are subjected to the action of arbitrary forces is solved by a new method based on the use of finite differences only with respect to time [12]. The numerical analyses of the time dependences of stress concentration are carried out for hollow cylinders of different thickness under impact loading. The proposed method is tested by solving a problem of circular hole in an infinite body subjected to the action of impact loads over the entire surface. __________ Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 44, No. 1, pp. 7–13, January–February, 2008.     

A Model of Fracture of Fibrous Concrete

We propose a model of fracture of composite materials similar to fibrous concrete. The stressed state of the matrix is described by macroscopic stresses averaged over a certain region near the end of the fiber. We study three possible fracture mechanisms: fracture of the matrix caused by the maximum macroscopic tensile stresses, rupture of the fiber, and fracture caused by the action of tangential stresses on the matrix–fiber interface. The probability of fracture of the composite under the action of each of these mechanisms is estimated.