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Use of Comparative Vacuum Monitoring Sensors for Automated, Wireless Health Monitoring of Bridges and Infrastructure
Published in Nigel Powers, Dan M. Frangopol, Riadh Al-Mahaidi, Colin Caprani, Maintenance, Safety, Risk, Management and Life-Cycle Performance of Bridges, 2018
As an example, the data acquired from CVM fatigue tests on 2.54” (0.1”) thick 2024-T3 aluminum structure were used to calculate the 90% POD level for CVM crack detection. This POD curve, representing the 95% confidence level, is plotted in Figure 5. The maximum likelihood estimated POD function, representing the optimum performance for CVM crack detection, was calculated from equation (2) and is plotted alongside the 95% confidence bound. The overall POD value (95% confidence level) for CVM crack detection in 2.54 mm thick aluminum skin was determined to be 0.58 mm (0.023”). In this particular instance, it was desired to achieve crack detection before the crack reached 0.1” in length so this goal was achieved. In over 200 fatigue tests conducted using CVM sensors there were no false calls produced by the sensors.
Low-cycle fatigue life prediction assessment of notched aluminum 2024-T3 under cyclic axial loading
Published in Ships and Offshore Structures, 2023
Moharram Mohammadi, Armin Rahmatfam
Al 2024-T3 has enough strength, relatively low weight, big corrosion resistance and good workability. Thus, 2024-T3 aluminum alloy is widely used in the aerospace industry. This aluminum alloy is also widely used in various structural elements and a multitude of fastener holes. As it is well-known, the fastener holes have natural stress concentrations and potentially critical points at initiation and growth of fatigue cracks (Maximov et al. 2014). Some recent research works imply that the time spent in microstructurally small fatigue crack (MSFC) growth phase accounts for 50−70% of total fatigue life (Brockenbrough et al. 1994; Fan et al. 2001; Hochhalter 2010).