Study of Three Dimensional Crack Tip Location of Mortar by Acoustic Emission

by H. L. Chen, West Virginia Univ, Morgantown, United States,
C. T. Cheng, West Virginia Univ, Morgantown, United States,



Document Type: Proceeding Paper

Part of: Nondestructive Testing of Concrete Elements and Structures

Abstract:

Plain mortar specimens were tested under three-point bending. Experimental variables include the width of the specimen and the notch-to-depth ratio. The experimental results of 12 specimens are reported in this paper. A six-channel acoustic emission (AE) system was used to measure the crack tip location. The applied loading, load-point deflection and crack mouth opening displacement (CMOD) were recorded together with real time AE parameters. The critical effective crack length and critical stress intensity factor of each specimen were calculated using a size-independent equation and compared with the experimental observation. AE three-dimensional source location technique was applied to evaluate the interior effective crack length during the entire loading period. AE technique can locate the position and time of the crack initiation. The critical effective crack length were measured by AE source location at the maximum load. The critical stress intensity factor of each specimen was calculated from AE measurement and compared with the value calculated from CMOD measurement. The crack profile along the width indicated that the surface crack front proceeded faster than the crack front inside the body .

Subject Headings: Cracking | Stress waves | Mortars | Effective length | Stress analysis | Load factors | Emissions

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