Abstract
Ductile fracture in metals has been intensively studied over at least 8 decades and a number of relatively well established methods have been developed to characterise the fracture resistance of metal components in terms of critical fracture toughness parameter(s). The most widely used ‘fitness-for-service’ industry standards concerning evaluation of cracks or crack-like-flaws provides correlations to determine critical values of the stress intensity factor or the J integral as a function of temperature and component thickness (or crack front length). The most challenging aspect is how to take into account that the fracture toughness of metals can significantly depend on the degree of constraint characterised by stress triaxiality. On the other hand, damage mechanics is an alternative way of modelling progressive failure in materials. Depending on the damage model used, typically one or more damage variables are introduced at each material point, which range between 0 and 1, with 0 normally representing the undamaged state and 1 representing complete damage, which essentially means that a macro crack has formed or has propagated to the point. In this article, we will present and discuss the results of some finite element simulations conducted for a Single Edge Notched Tension (SENT) specimen using an explicit-dynamics solution procedure and a material model that accounts for ductile damage and plasticity. Due to the very refined mesh at the crack front, mass scaling is used to increase the minimum time increment ensuring stability and the effect of different choices of mass-scaling parameters are discussed.
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