On the comparision of crack closure evaluation using dynamic and static compliance measurements

A computer controlled dynamic compliance (DYNACOMP) measurement technique has been used to investigate crack closure in three medium carbon microalloyed steels. The principles of the dynamic compliance technique are briefly presented. The crack closure loads determined using dynamic compliance technique were compared with the static compliance measurements obtained with a crack mouth opening (CMOD) gauge. The closure loads obtained with the dynamic compliance technique compared well with the static compliance measurements. The results indicate the sensitivity of the dynamic compliance measurements to the micromechanics of fatigue crack growth.