Double torsion test of soda-lime galss/air system and acoustic emission during crack progagation

Abstract

The effects of specimen thickness, crosshead speed and the initial crack length on K$_I-\upsilon$ diagrams of soda-lime glass/air system were investigated using double torsion technique and acoustic emission. In this work, crack velocity varied between $10^{-6}$ and $10^{-4}$ m/sec and the stress intensity factor varied between $5\times10^5$ and $9\times10^5 Nm^{-1/3}$. The compliance, fracture toughness parameter, n, and n$^\star$ decreased as increasing the specimen thickness K$_I-\upsilon$ and K$_I$-dN/dt curve shifted toward larger K$_I$ at constant $\upsilon$ and dN/dt, but n and n$^\star$ were not changed with the increase of crosshead speed. The load deviated from the linearity, Ps, was changed by changing the shape of crack front. But beyond the peak load, P$_i$, the curve was not changed. The number of acoustic emission counts per unit crack extension was approximately constant for the same specimen. The time to failure was reduced with increasing the crosshead speed.