THE EQUIVALENT ELASTIC CRACK .1. LOAD-Y EQUIVALENCES

The use of crack growth resistance curves (R-DELTAa) to predict the behaviour of cracked specimens is a well established practice for ceramic and cementitious materials. When the cohesive crack model can be applied to these materials it is shown that the use of R-DELTAa curves is equivalent to setting up an elastic equivalence that greatly simplifies the computations. This equivalence has its drawbacks and limitations. This paper analyzes a class of equivalences - the load (P) versus another variable - between cracked cohesive materials and linear elastic ones, ascertaining its applicability to the interpretations of fracture data.