Development of Numerical Model for Brittle Crack Propagation/Arrest Behaviors

Abstract

A new model for dynamic crack propagation and arrest in steel plates is proposed. The model is based on the local fracture stress criterion and incorporates the influence of plastic deformation on the tip of a dynamically propagating crack. Under extremely high applied stress intensity factor, the crack-tip plastic zone develops so as to decrease plane strain condition region along the crack front. This leads to the relaxation of plastic constraint and the lowering tensile stress at the crack tip. It is thereby difficult for the crack to keep propagating. The proposed model is applied to the past published ultra-wide crack arrest tests, where a crack was arrested even if stress intensity factor K was higher than arrest toughness Kca obtained by the standard crack arrest test. Although the results have been unexplained for many years, the numerical results of the proposed model show good agreement with the past test results. It is found out that the primary reason of the crack arrest of ultra-wide plate tests can be explained by the loss of plane strain condition at the crack front.