Experimental investigation of high frequency pulse loading on fatigue crack growth in 5052-H32 series aluminum

Acoustic waves are widely used in structural health monitoring (SHM) for detecting fatigue cracking. The strain energy released when a fatigue crack advances has the effect of exciting acoustic waves, which travel through the structures and are picked up by the sensors. Piezoelectric wafer active sensors (PWAS) can effectively sense acoustic waves due to fatigue-crack growth. Conventional acoustic-wave passive SHM, which relies on counting the number of acoustic events, cannot precisely estimate the crack length. In the present research, a novel method for estimating the crack length was proposed based on the high-frequency resonances excited in the crack by the energy released when a crack advances. In this method, a PWAS sensor was used to sense the acoustic wave signal and predict the length of the crack that generated the acoustic event. First, FEM analysis was undertaken of acoustic waves generated due to a fatigue-crack growth event on an aluminum-2024 plate. The FEM analysis was used to predict the wave propagation pattern and the acoustic signal received by the PWAS mounted at a distance of 25 mm from the crack. The analysis was carried out for crack lengths of 4 and 8 mm. The presence of the crack produced scattering of the waves generated at the crack tip; this phenomenon was observable in the wave propagation pattern and in the acoustic signals recorded at the PWAS. A study of the signal frequency spectrum revealed peaks and valleys in the spectrum that changed in frequency and amplitude as the crack length was changed from 4 to 8 mm. The number of peaks and valleys was observed to increase as the crack length increased. We suggest this peak–valley pattern in the signal frequency spectrum can be used to determine the crack length from the acoustic signal alone. An experimental investigation was performed to record the acoustic signals in crack lengths of 4 and 8 mm, and the results were found to match well with the FEM predictions.

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High frequency fatigue crack growth and threshold behavior in monocrystalline copper

Scripta Metallurgica ◽

10.1016/0036-9748(80)90282-3 ◽

1980 ◽

Vol 14 (7) ◽

pp. 749-753 ◽

Cited By ~ 3

Author(s):

S.E. Stanzl

Keyword(s):

Fatigue Crack ◽

Fatigue Crack Growth ◽

Crack Growth ◽

High Frequency ◽

Threshold Behavior

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Fatigue Crack Growth Behavior of High Carbon Steel (SM53C) by Using Induction Hardening

ASME 2008 International Manufacturing Science and Engineering Conference, Volume 2 ◽

10.1115/msec_icmp2008-72452 ◽

2008 ◽

Author(s):

Hyun Bae Jeon ◽

Tae Hoon Song ◽

Sung Ho Park ◽

Sun Chul Huh ◽

Won Jo Park

Keyword(s):

Fatigue Crack ◽

Carbon Steel ◽

Fatigue Crack Growth ◽

Crack Growth ◽

High Frequency ◽

High Carbon Steel ◽

Induction Treatment ◽

Special Focus ◽

High Carbon ◽

High Frequency Induction

Recently, with the high performance and efficiency of machine, there have been required the multi-functions in various machine parts, such as the heat resistance, the abrasion resistance and the stress resistance as well as the strength. Fatigue crack growth tests were carried out to investigate the fatigue characteristics of high carbon steel (SM53C) experienced by high-frequency induction treatment. The influence of high-frequency induction treatment on fatigue limit was experimentally examined with the special focus on the variation of surface microstructure and the fatigue crack initiation and propagation through fractography. Also, the shape of hardening depth, hardened structure, hardness, and fatigue-fracture characteristics of SM53C composed by carbon steel are also investigated.

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