The results shown in this paper are the out-of-plane displacement signals versus time (where zero time corresponds to the start of the operation of the source) obtained on the top surface of the steel cylinder at a propagation distance of 100 mm (radial direction) from the capillary fracture.
Since the actual temporal shape and the rise time of the source generated by the glass capillary fracture are not known, different shapes and rise times were evaluated.
Thus, it appears that the release of the normal stresses from the glass capillary fracture is not a step in time.
Re-examination of NIST acoustic emission sensor calibration: Part I--modeling the loading from glass capillary fracture," J.
Since use of a capacitance reference sensor accounts for the above spatial and temporal aspects for glass capillary fractures, it is recommended that use of an alternate calibration approach using an analytical solution, which presently cannot rationally account for the actual values of these parameters, be modified in E1106-07.