scholarly journals Fatigue crack analysis of ferrite material by acoustic emission technique

2019 ◽  
Vol 13 (2) ◽  
pp. 5074-5089
Author(s):  
Md. T. I. Islam Khan ◽  
A. A. Rashid ◽  
R. Hidaka ◽  
N. Hattori ◽  
Md. M. Islam
Keyword(s):  
Acoustic Emission ◽  
Fractal Dimension ◽  
Crack Propagation ◽  
Fatigue Loading ◽  
Dynamic Monitoring ◽  
Dynamic Crack ◽  
Propagation Behavior ◽  
Novel Approach ◽  
Crack Volume ◽  
Long Time

Recently in various fields, numerous researches are going on for the assessment of material damage on the basis of crack initiation and propagation. Various methods are available in NDT for this purpose, among which analysis using released acoustic emission (AE) waves due to crack propagation is very effective due to its dynamic monitoring features. Various approaches are proposed for long time to make it an ideal method for accurate monitoring of crack behaviors in materials. In fragmentation theory there are some proportionality among the relations of AE event, AE energy, area and volume of cracks etc., which are calculated from the released AE waves from any dynamic crack. It has been found that the necessity of calculating the fractal dimension is important in verifying these relationships. This parameter is emphasized for determining the geometry of the irregularity in crack surface and crack volume. In this paper a novel approach based on image processing is proposed to find out the fractal dimension for analyzing the crack propagation characteristics. Finally, the proportionality relationships of AE parameters with crack propagation behavior in ferrite cast iron under fatigue loading are demonstrated experimentally.

The Crack Growth Evaluation of A335 P22 Steels by Acoustic Emission

2005 ◽  
Vol 297-300 ◽  
pp. 2083-2089
Author(s):  
Gee Wook Song ◽  
Jung Seob Hyun ◽  
Sung Ho Chang ◽  
Bum Shin Kim
Keyword(s):  
Acoustic Emission ◽  
Crack Propagation ◽  
Crack Growth ◽  
Compact Tension ◽  
Fatigue Tests ◽  
Remaining Service Life ◽  
Operation Conditions ◽  
Long Time ◽  
Actual Operation ◽  
Stress Ratios

Acoustic emission (AE) technique was used to investigate fatigue crack growth on compact tension specimens of aging materials at room temperature. Test materials have been sampled steam pipe serviced the actual operation conditions for a long time in fossil power plant. The compact tension test specimens were subjected to load stress ratios of 0.33, 0.5, and 0.66. All the fatigue tests were performed at a frequency of 1Hz. The test results indicate that acoustic emission counts show reasonable correlation with crack propagation rates for applied stress ratios. When the crack growth rates increase, AE’s counts and energies show increment. Also, the higher stress ratios, the faster crack propagation rates. Based on these relationships it may be possible to predict the remaining service life of fatigue-damaged steam pipes.

scholarly journals Role of LPSO Phase in Crack Propagation Behavior of an As-Cast Mg-Y-Zn Alloy Subjected to Dynamic Loadings

Materials ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 498 ◽  
Author(s):  
Xuezhi Shi ◽  
Yunqian Long ◽  
Huiqiu Zhang ◽  
Liqiao Chen ◽  
Yingtang Zhou ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Crack Propagation ◽  
Crack Opening ◽  
Dynamic Crack Propagation ◽  
Dynamic Crack ◽  
Lpso Phase ◽  
Propagation Behavior ◽  
Dynamic Loadings ◽  
Crack Propagation Behavior

In this work, the role of long period stacking ordered (LPSO) phase in the crack propagation behavior of an as-cast Mg95.5Y3Zn1.5 alloy was investigated by dynamic four-point bent tests. The as-cast Mg95.5Y3Zn1.5 alloy is mainly composed of Mg matrix, 18R LPSO phase located at the grain boundaries and 14H LPSO phase located within the Mg matrix. The alloy exhibits excellent dynamic mechanical properties; the yield stress, maximum stress and strain to failure are 190.51 ± 3.52 MPa, 378.32 ± 4.26 MPa and 0.168 ± 0.006, respectively, at the strain rate of ~3000 s−1. The LPSO phase effectively hinders dynamic crack propagation in four typical ways, including crack tip blunting, crack opening inhibition, crack deflection and crack bridging, which are beneficial to the mechanical properties of the alloy under dynamic loadings.

Acoustic emission detection and prediction of fatigue crack propagation in composite patch repairs using neural network

2016 ◽  
Vol 30 (1) ◽  
pp. 3-29 ◽  
Author(s):  
A Chukwujekwu Okafor ◽  
Navdeep Singh ◽  
Navrag Singh ◽  
Benjamin N Oguejiofor
Keyword(s):  
Acoustic Emission ◽  
Crack Propagation ◽  
Crack Length ◽  
Back Propagation ◽  
Fatigue Loading ◽  
Matrix Cracking ◽  
Composite Patch ◽  
Patch Repairs ◽  
Aluminum Panels ◽  
Emission Detection

This article presents the results of acoustic emission (AE) monitoring of crack propagation in 2024-T3 clad aluminum panels repaired with adhesively bonded octagonal and elliptical boron/epoxy composite patches using FM-73 adhesive under tension–tension fatigue loading. Two crack propagation gages and four broadband AE sensors were used to monitor crack initiation and propagation, respectively. The acquired AE signals were processed in time and frequency domain to identify sensor features correlated with fatigue cycle and crack propagation, which were used to train neural networks for predicting crack length. The results show that AE events are correlated with crack propagation, and crack propagation signals can be differentiated from signals due to matrix cracking, fiber breakage, and shear of the composite patch. Three back-propagation cascade feed-forward networks were trained to predict crack length using number of fatigue cycles, number of AE events, and number of fatigue cycles and number of AE events together as inputs, respectively. It was found that network with fatigue cycles as input gave good results, while the network with just AE events as input gave greater error. However, the network using both fatigue cycles and number of AE events as inputs to predict crack length gave much better results.

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