A comparative analysis of several nonlocal fracture criteria

Comparative analysis has been carried out for three nonlocal fracture criteria (NLFC) in application to plane problems: the average stress fracture criterion (ASFC), the minimum stress fracture criterion (MSFC) and the fictitious crack fracture criterion (FCFC). Each of them may be considered as an equality for a particular form of the general nonlocal strength functional. The criteria contain two material parameters: a characteristic length and the tensile strength (ASFC and MSFC) or the critical stress intensity factor (FCFC). The criteria have been used for a strength description of a plate containing a smooth stress concentrator (circular hole) or a singular stress concentrator (central straight crack). It has been ascertained that ASFC and FCFC lead to identical results for the symmetrically loaded central straight crack. ASFC and MSFC map be successfully used for the description of strength of bodies with smooth as well as singular concentrators, while FCFC gives incorrect predictions for large smooth concentrators and for some other cases. A comparison of the predicted and experimental data has shown that ASFC is preferable in most cases; nevertheless, there exists a systematic deviation of experimental points from the criterion predictions.