Failure mechanism in porous materials under compression: crackling noise in mesoporous SiO₂

Abstract

The failure mechanism of porous materials under uniaxial stress has been investigated experimentally. Microporous SiO₂, Vycor, has been subjected to slowly increasing compressive uniaxial stress with stress rates between 0.2 and 12.2 kPa/s. With increasing stress the strain changes stepwise with acoustic emission correlated with each volume collapse. The acoustic emission followed the characteristics of ‘crackling noise’ with a power law distribution over an exceptionally large interval of 6 decades at the slowest stress rate. The power law exponent is −1.39. Possible applications in mining industry and others are discussed.

Keywords:

• crackling noise
• cracking
• mechanical testing
• porous media
• silicates

Acknowledgements

Antoni Planes and Eduard Vives acknowledge financial support from CICyT (Spain), Project No. MAT2010-15114.