Nondestructive sizing and localization of internal microcracks in fatigue samples

Rokhlin, S. I.; Kim, Jin‐Yeon; Xie, B.; Zoofan, B.

doi:10.1016/j.ndteint.2007.02.001

Cited by 24 publications

(14 citation statements)

References 6 publications

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“…Two dwell cracks on a longitudinal section of a fatigue tested Ti6242 sample were selected for further analysis, as shown in Figure 7a. IPF map (Figure 7b) demonstrated that both dwell cracks appeared in regions with basal planes nearly perpendicular to the loading direction, consistent with previous reports [10,11,30,[38][39][40]. The Schmid factor map for prism slip (Figure 7c) showed that the areas neighboring both cracks were oriented favorably for prism slips.…”

Section: Microtexture and Stress Redistributionsupporting

confidence: 88%

“…The secondary cracks beneath the LCF fracture surfaces, shown in the Figure 5 (a), exhibited classic secondary crack morphology orienting nearly 45° to the loading direction with a high Schmid factor and the cracks formed along dislocation slip bands [28]. Different from the classic morphology, secondary cracks of the dwell sensitive alloy after LCDF were nearly perpendicular to the loading direction, which was consistent with the observation by Rokhlin et al [29,30].…”

Section: Secondary Cracks and Slip Morphologysupporting

confidence: 87%

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Comparison of the Dwell Fatigue Behavior of Ti6242 And Ti6246

Qiu

Lei

et al. 2016

Proceedings of the 13th World Conference on Titanium

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The dwell effects of Ti624x (x=2 to 6) alloys, including dwell fatigue life debit, fracture mode and strain accumulation, were characterized and compared. The different dwell fatigue behaviors of Ti6242 and Ti6246 were attributed on the fundamental level to the dual effects of Mo: It decreases the transus of titanium and, as a slow diffuser, reduces the rate of phase transformation from to . A higher Mo content encourages nucleation of multiple variants of laths and promotes the transition from aligned colonies to basketweave microstructure during cooling after forging. As a result both the grain size and microtexture intensity of grains in the two-phase processed and heat treated microstructure are reduced. Smaller grain size of the alloys with higher Mo content produces smaller slip band spacing and reduces accumulated strain during dwell fatigue, thus reducing propensity for crack initiation.

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Section: Microtexture and Stress Redistributionsupporting

confidence: 88%

Section: Secondary Cracks and Slip Morphologysupporting

confidence: 87%

Comparison of the Dwell Fatigue Behavior of Ti6242 And Ti6246

Qiu

Lei

et al. 2016

Proceedings of the 13th World Conference on Titanium

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“…The ultrasonic monitoring technique has been developed to detect the initiation and expansion of the fatigue crack in the fatigue testing [4][5][6][7][8][9][10]. In most of these monitoring techniques, data were recorded under pausing the fatigue tester [4,7,8,10,11], and these measurements can be called as stationary ultrasonic measurements.…”

Section: Introductionmentioning

confidence: 99%

Size Estimation of Fatigue Crack Appearing at Bolt Joints of Aluminum Alloy Plates by Synchronized SAW Measurement

Wagle

Katô

2010

Exp Mech

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The synchronized ultrasonic measurement with the surface acoustic wave (SAW) was carried out during the fatigue testing of bolted specimens of the aluminum alloy in synchronization with a fatigue cycle. The stationary SAW measurement was also carried out in the fatigue testing under pausing the fatigue tester at the mean load. In both measurements, the intensity of the scattered wave gradually increased with the number of fatigue cycles in the fretted region ahead of a bolt hole due to surface roughness, and the steep increment occurred following appearance and propagation of the fatigue crack. The steep increment was detected earlier in the synchronized measurement than that in the in-process measurement. In the synchronized SAW measurement, the intensity of the reflection from the fatigue crack increased with increasing stress level in the fatigue cycle. Then, the crack length was estimated with the intensity change of the reflection from the crack in the fatigue cycle following the Elber's model modified by Suresh on the crack opening and closure following the stress intensity factor. The method developed in the present work shows the potential of the synchronized surface acoustic wave measurement as a tool for the early detectability of the fatigue crack as well as for the evaluation of crack opening/closure behavior in the bolted joint.

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“…8) These were carried out by pausing the fatigue tester, and it was unable to examine the change in the ultrasonic wave signal in a fatigue cycle. To overcome this difficulty, Min and Kato 11) and Rokhlin et al 9,10) carried out the real-time ultrasonic measurement during the fatigue testing of the specimen to obtain the change in the ultrasonic signals at any loading level in a fatigue cycle, but still remained limitations. The authors 12,13) presented the other way of the ultrasonic monitoring technique, called as the synchronized ultrasonic measurement, in which the ultrasonic pulse signal is generated in synchronization with the loading cycle in the fatigue testing to obtain the data at any stress levels in a fatigue cycle, and they evaluated a crack length from the change in the SAW intensity reflected from the fatigue crack with the stress level in the fatigue cycle.…”

Section: Introductionmentioning

confidence: 99%

“…Guan et al 16) also estimated the depth of the slot by the laser generated surface acoustic wave. Rokhlin and Kim 9,10) reported that there are different types of mode conversion of the surface acoustic wave at the root of the pit, and they estimated the depth of the pit by using the converted wave. These reports show the effectiveness of the mode conversion of the Rayleigh wave for evaluation of the crack depth.…”

Section: Introductionmentioning

confidence: 99%

Depth Evaluation of Fretting Fatigue Crack Appearing at Bolt Joints of Aluminum Alloy Plates by Synchronized Surface Acoustic Wave Measurement

Wagle

Katô

2012

Mater. Trans.

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The surface acoustic wave (SAW) measurement was carried out for the bolted specimen of aluminum alloy by synchronizing the ultrasonic pulsation with a fatigue cycle in the fatigue testing. The reflection from the crack increased in the loading stage of the fatigue cycle, reached maximum and then decreased in the unloading stage of the fatigue cycle. The sigmoidal intensity change of the reflection from the fatigue crack in a fatigue cycle occurred following opening/closing behavior of the crack, and the intensity took the maximum value when the crack was fully opened. The SAW intensity distribution between the crack and the bolt hole edge was also analyzed to evaluate the depth of the crack: the SAW intensity distribution after the crack root was subjected to the band-pass filtering to recognize the creeping wave (the longitudinal wave) reflected from the crack tip, and then the crack depth was estimated from the propagation time of the creeping wave from the crack root to the crack tip, which was in good agreement with the value measured in the cross section of the specimen and evaluated through the scanning acoustic analysis.

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Nondestructive sizing and localization of internal microcracks in fatigue samples

Cited by 24 publications

References 6 publications

Comparison of the Dwell Fatigue Behavior of Ti6242 And Ti6246

Comparison of the Dwell Fatigue Behavior of Ti6242 And Ti6246

Size Estimation of Fatigue Crack Appearing at Bolt Joints of Aluminum Alloy Plates by Synchronized SAW Measurement

Depth Evaluation of Fretting Fatigue Crack Appearing at Bolt Joints of Aluminum Alloy Plates by Synchronized Surface Acoustic Wave Measurement

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