Monitoring of single-particle fragmentation process under static loading using acoustic emission

The fragmentation of single particle is one of the common observations in stressed soils. Individual particles are generally randomly shaped and exhibit twisted and discrepant fracture features. Conventional descriptions based on either strength prediction or comminution energy estimation are more or less statistical, which inevitably brings difficulties to understand the physical mechanism of fragmentation. As an attempt to overcome such limitations, this study presents an Acoustic Emission (AE) testing method to monitor the process of the single-particle fragmentation. AE testing is considered as an effective non-destructive technique and is capable of detecting micro-level defects inside a material. In the tests, the activity and the frequency characteristics of the AE signals were recorded and analyzed. It was found that the process of particle fragmentation was highly distinguished by AE characteristics. The AE activity was relatively low at first, followed by an inactive period. Finally, the AE signals tended to be significant active and exhibited a clustering of high frequency AEs before the impending fracture failure. This feature provides a useful insight to clarify the inner crack initiation and growth during the process of particle fragmentation. The technique is also promising for further applications such as particle fracture issues in granular systems which consist of numerous single grained particles.