Quantitative Fractography of Mixed-Mode Fracture in Soda Lime Silica Glass

摘要

Fracture surfaces of soda lime silica glass failed from controlled surface cracks in diametral compression, under mixed-mode loading conditions were studied using fractography. Mode mixity was introduced by orienting indent precracks in different directions with respect to the loading axis. The mixed-mode fracture surfaces were characterized by an absence of the mist region. The hackle markings on the mixed-mode fracture surfaces appear as lances and differ from those observed on surfaces failed in pure mode I. Atomic force microscopy on the mixed-mode fracture surfaces revealed that the features at different regions are similar and differ only by scale. Fracture surface measurements for mixed-mode loading are compared to the measurements for mode I loading. The stress intensity at microbranching was determined to be a constant irrespective of the loading conditions. The practical implications of these observations are that forensic analyses can be used without a priori knowledge of the loading conditions.