J-Q characterization of propagating cracks

An investigation is performed to determine to what extent the state at a gr owing crack tip vicinity can be characterised by J and Q calculated from FE analyses of successively stationary crack tip positions. FE models in two- dimensionals of single edge notch bend and double edge cracked panel specim ens with several different crack lengths are used to cover a range of load and constraint levels. The stress and strain fields are compared between di fferent specimens keeping J- and Q-values equal. A remeshing technique in t he commercial FE-code ABAQUS is used to enhance the efficiency of the analy sis. The results show that the J-Q-theory provides reasonably accurate crac k tip characterization also for growing cracks. This leads to the conclusio n that FE analyses of successive stationary cracks rather than full FE prop agation analyses are sufficient. The limit of validity for propagation is s imilar to the validation limit for the stationary case, although somewhat m ore restrictive.