Cyclic Loading Behaviour Of Soda-Lime Silicate Glass Using Indentation Cracks

Cyclic loading behaviour of soda-lime silicate glass was studied using Vickers indentation flaws. Glass bars were indented in air using a load of 9.8 N. Some samples were annealed in order to remove the indentation residual stress field. Both as-indented and annealed specimens were subjected to static and cyclic bending tests in a water environment using a four-point bending configuration. The influence of maximum stress on lifetime was considered. Crack propagation was examined by fractography and fracture patterns were similar to those observed in static fatigue. Characteristic fracture markers were seen on samples subjected to cyclic load. Experimental results were compared with theoretical predictions which were obtained on the basis of typical sub-critical crack growth behaviour. Precise determination of crack shape and residual stress factors were shown to play an important role in lifetime predictions.