LIGAMENT FIELDS AHEAD OF A CRACK TIP UNDER PIECE-WISE ELASTIC-PLASTIC MODEL

A constraint variable of ν ep that represents the ratio of elastic to plastic deformation is introduced. An approximate ligament field of mode Ⅰ plane-strain crack problems under Piece-wise elastic-plastic model is obtained. The investigation emphasis on energy densities other than stresses. It is concluded that elastic energy is still important in elastic-plastic fracture process. There is a non-uniform distribution of the energy density around a crack tip. The decreasing of constraint variable ν ep leads the near tip pattern of energy distributions gradually become uniform and so leads high critical values of J integral.