The crack propagation mechanism of thick plates is difficult to describe accurately, and thus, it is difficult to predict the lifetimes of thick plate structural cracks in extreme construction environments. In this paper, a theoretical model of the time-integrated crack propagation that accounts for the thickness effect is established. The constraint factor is introduced to characterize the thickness effect of crack propagation, and the constraint factor formula was obtained by fitting the experimental results. The results of the fatigue crack growth tests and the crack propagation theoretical predictions for Q345D specimens showed the time-integrated crack propagation model predicts the crack propagation more accurately in the initial stage and during the stable expansion stage of crack propagation. These results have guiding significance for the fatigue life prediction of equipment with thick plate structural features.INDEX TERMS Thick plate, crack propagation, crack closure, fatigue test, time integration method.

In the above-named work by G. Sergiadis et al. (see ibid., vol.7, p.381-5, 1988), an exact solution to the electromagnetic field distribution inside a conductive cylinder of finite length was proposed for estimation of the thermal losses in biological tissues under MRI conditions. The commenters claim to show that such a solution is untrue for a finite-length cylinder, and that the related numerical treatments in the work of Sergiadis et al. are for an infinite cylinder, not a finite cylinder.