Computer-Controlled Stable Crack Growth as a Reliable and Fast Method to Determine Subcritical Crack Growth

Subcritical crack growth of synthetic fused silica glass is investigated using the single-edge-V-notched-beam method. The measurement was performed in a very stiff four-point bending device, which is equipped with a computer-aided control system. This technique enables several loading cycles of controlled crack growth with one measurement and sample. The control system is based on an online compliance measurement that enables an automatic measurement routine without much operation of the user and without the necessity of the optical observation of the crack. The crack velocity as a function of the applied stress intensity factor was determined by analysing the measured specimen compliance. The presented method allows determining a large number of v-K-I curves under identical conditions by measuring only one sample.