Small fatigue crack behavior in 7075-T651 aluminum as monitored with Rayleigh wave reflection

Journal Article · Sun Aug 01 00:00:00 EDT 1993 · Metallurgical Transactions, A (Physical Metallurgy and Materials Science); (United States)

DOI:https://doi.org/10.1007/BF02657852· OSTI ID:5729750

Hirao, M; Tojo, K; Fukuoka, H ^[1]

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1. Osaka Univ., Toyonaka, Osaka (Japan)

Small fatigue crack growth in 7075-T651 aluminum is periodically monitored with an ultrasonic Rayleigh wave technique. The wideband reflection signals are digitized and stored in the computer memory to permit the signal processing in the frequency domain. With the help of the constructed three-dimensional (3-D) reflection coefficient, the reflection amplitude spectra yield the measurements of the crack depth, if larger than 0.062 mm, and the crack closure stress. Acoustically obtained da/dN-[Delta]K[sub eff] relations describe the anomalous growth behavior of small surface crack, extending from the late small crack regime to the large crack regime passing through the minimum growth rate. The split spectrum processing proves to be useful in removing the grain noises to illuminate the target echoes, which is necessary to detect the nucleation and characterize the cracks smaller than 0.1 mm in depth. Discussions on the computer-controlled, automated, in situ monitoring system are provided.

• OSTI ID: 5729750
• Journal Information: Metallurgical Transactions, A (Physical Metallurgy and Materials Science); (United States), Vol. 24:8; ISSN 0360-2133
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM BASE ALLOYS
CRACK PROPAGATION
ACOUSTIC DETECTION
ACOUSTIC MONITORING
FATIGUE
GROWTH
RAYLEIGH WAVES
ACOUSTIC MEASUREMENTS
ALLOYS
ALUMINIUM ALLOYS
CHARGED PARTICLE DETECTION
DETECTION
MECHANICAL PROPERTIES
MONITORING
RADIATION DETECTION
SEISMIC SURFACE WAVES
SEISMIC WAVES
360103* - Metals & Alloys- Mechanical Properties