Crack Detection in Crane Shafts using Acoustic Emission

Acoustic emission testing of naval portal crane shafts was carried out at the Ferguson Structural Engineering Lab at the University of Texas at Austin. The crane shafts were provided by the United States Navy in order to examine the feasibility of using acoustic emission to find fatigue cracks in existing shafts. The results of the test program were used to develop a field test procedure based on acoustic emission technology.

The laboratory testing comprised fatigue cycling of the shaft at various load levels while monitoring with digital acoustic emission instrumentation. A specially designed stand was used to apply the torsional load to the shaft via its keyway, the same way as loads are transferred while in the crane. A field test at Pearl Harbor Naval Shipyard verified the viability and effectiveness of the proposed method in a real setting, and was effective in calibrating data obtained in the laboratory.

The data was analyzed using standard acoustic emission parameters. The data confirms that acoustic emission can detect the presence and growth of fatigue cracks under torsional loads. Emission from the crack is significant and readily detectable at thresholds commonly used in field testing environments.