Effects of polyaxial stress state on static fatigue behavior of soda-lime glass.

Abstract

Soda-lime glass specimens with an indented induced flaw at the center, were fractured under a constant load applied by the four-point bending of the plates, concentric-ring loading of disks, and diametral compression of disks. Then, after indentation, the specimens were quenched in oil to remove the residual tensile stress near the crack tip. The time taken until failure increased with decreasing applied stress, and the degree of the increase was significantly higher in the diametral compression than in other stressing modes. This result was completely contrary to our previous report where a vacuum annealing treatment had been employed to remove residual stress. Further, the scatter in the fatigue data for equibiaxial tension was obviously less than that in the previous report. The subcritical crack-growth parameters, n, determined from a straight line on a logarithmic plot of the fatigue life time as a function of the applied stress were 15.2 for diametral compression, 9.7 for equibiaxial tension, and 9.1 for uniaxial tension. The higher value of n in diametral compression can be attributed to the fact that the crack growth was restricted by the higher hydrostatic compressive stress.