Crack development studied by acoustic emission technique

Abstract

Acoustic emission monitoring has been used extensively in field and laboratory tests. Locating acoustic emissionsources has been proven to be a useful non-destructive analytic technique to study the progressive damage process of rock at itstrue stress states. In most cases, the P-wave velocity was treated as a known value. However, P-wave velocity is usually difficult toobtain since ultrasonic sensors are very sensitive to sudden shocks. In the present study, acoustic emission source location wasdeveloped by treating P-wave velocity as an unknown variable and then solving the problem by least square method. The accuracywas first validated by a benchmark test. Another test was conducted on granite in MTS 815 system with acoustic emissionmonitoring to demonstrate its application in study of damages within specimen under constant loading. The results indicated thatthe source location determined by the algorithm proposed in this paper can predict the damage zone fairly well.