VICKERS INDENTATIONS IN GLASS .2. COMPARISON OF FINITE-ELEMENT ANALYSIS AND EXPERIMENTS

This paper presents a comparison of a three-dimensional finite element numerical analysis of Vickers indentation with an experimentally obse rved indentation load-depth (P-h) relation on soda-lime glass. Several mechanical properties, such as yielding stress, strain hardening and elastic modulus, are then estimated from the analysis of the experimen tal P-h curve. This paper also compares the experimentally-measured re sidual stress field around a Vickers indentation at the surface of gla ss with an FEM numerical calculation. The FEM calculation uses Mises e lastoplasticity to describe the residual stress state at the unloading . The comparison shows a very good agreement between the numerical cal culation and the experimental results for the P-h relation, the Mises stress and the hydrostatic stress. The results further confirm that th e residual stress field close to the indentation is a non-equal hi-axi al stress field, which is not circular in shape but reflects the shape of the indentation impression The formation of radial cracks also cau ses significant modification of the stress field. The FEM analysis sho ws that the P-h relation can provide much useful information on mechan ical properties using the analysis developed here.