R. Banerjee et Bk. Sarkar, DEFORMATION OF SODALIME GLASS UNDER REPEATED INDENTATION, Transactions of the Indian Institute of Metals, 49(4), 1996, pp. 611-615
Fracture mechanics studies on glass by indentation techniques have bec
ome predominant in recent times. Several techniques have been adopted
to initiate crack in the material followed by repeated indentation at
the same spot for crack growth and fatigue studies. However glass subj
ected to to repeated indentation at a point prior to crack initiation
at a subcritical loads phenomenological to metal fatigue was not syste
matically investigated. Experiment was conducted to initiate cracks on
normal sodalime glass by repeated indentation at a single point with
different subcritical (0.1 N, 0.15 N, 0.25 N, 0.50 N, 1.0 N) loads. Ex
periment was discontinued the moment crack was observed to occur. The
length of diagonals were found to increase with each indentation leadi
ng to crack initiation. This observation was analysed considering the
plastic component and the residual force developed during each indenta
tion cycle and a model has been developed to correlate the contributio
n of cumulative residual stress for crack initiation.