An experimental failure model based on triaxiality factor and Lode angle for X-100 pipeline steel

pipelines. In order to extract the failure properties of this material a series of experiments on smoothand notched round bars with different notch radius and flat notched specimens with different notchradius and notch depth in tension are done. Whereas this material is severely anisotropic (Lanckfordratio around 0.5), specimens are cut in different directions within the plane of rolling.Lode angle, which is a recently introduced parameter in the fracture of ductile materials and containsthe effect of third invariant of deviatoric stress tensor, along with triaxiality factor, showing the effectof hydrostatic stress, are studied in the fracture of this material. The load-displacement curves andpictures taken by 2 photo camera are used to study the effects of anisotropy, triaxiality factor and Lodeangle on the failure of this material. Finally an experimental failure criterion is developed to model thefailure of this material. In this failure criterion, strain at fracture initiation is a function of X and TF.Models that take into account the effect of Lode angle, Triaxiality factor and anisotropy in plasticityand damage are the current state of the art in the research of ductile materials.