On the fundamental energy argument of elastic fracture mechanics

Energy arguments remain, even today, as probably the most fundamental physically-reasoned justification for the application of linear elastic fracture mechanics to brittle materials. Accordingly, they have attracted and continue to attract quite a number of investigations. Not all of these studies employ the same approach. Unfortunately, nor do they all lead to the same conclusions regarding the implications of elastic fracture mechanics. Here, by examining the energy balance of fracture mechanics from a classical physics viewpoint, equivalent valid approaches are identified. This in turn enables the various contributions over the years to be placed in perspective with respect to whether or not they are correct.