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| Title: | Acoustic emission detection and prediction of fatigue crack propagation in composite patch repairs using neural networks |
| Author (s): | Okafor, Anthony Chukwujekwu Singh, Navdeep Singh, Navrag |
| Department/Lab Affiliations: | Intelligent Systems Center Mechanical & Aerospace Engineering |
| Keywords: | crack detection fatigue cracks maintenance engineering neural nets |
| Subject Terms: | Acoustic emission testing. Composite materials. Polymers. |
| Issue Date: | 2007 |
| Publisher: | American Institute of Physics |
| Citation: | Okafor, A C., Navdeep Singh, and Navrag Singh. “Acoustic Emission Detection and Prediction of Fatigue Crack Propagation in Composite Patch Repairs Using Neural Networks." Review of Progress in Quantitative Nondestructive Evaluation” Volume 894, pp. 1532-1539, 2007. |
| Abstract: | An aircraft is subjected to severe structural and aerodynamic loads during its service life. These loads can cause damage or weakening of the structure especially for aging military and civilian aircraft, thereby affecting its load carrying capabilities. Hence composite patch repairs are increasingly used to repair damaged aircraft metallic structures to restore its structural efficiency. This paper presents the results of Acoustic Emission (AE) monitoring of crack propagation in 2024-T3 Clad aluminum panels repaired with adhesively bonded octagonal, single sided boron/epoxy composite patch under tension-tension fatigue loading. Crack propagation gages were used to monitor crack initiation. The identified AE sensor features were used to train neural networks for predicting crack length. The results show that AE events are correlated with crack propagation. AE system was able to detect crack propagation even at high noise condition of 10 Hz loading; that crack propagation signals can be differentiated from matrix cracking signals that take place due to fiber breakage in the composite patch. Three back-propagation cascade feed forward networks were trained to predict crack length based on the number of fatigue cycles, AE event number, and both the Fatigue Cycles and AE events, as inputs respectively. Network using both fatigue cycles and AE event number as inputs to predict crack length gave the best results, followed by Network with fatigue cycles as input, while network with just AE events as input had a greater error. |
| Type: | Article - Conference proceedings text |
| In Title: | Review of Progress in Quantitative Nondestructive Evaluation |
| Copyright Notice: | This material is presented to ensure timely dissemination of scholarly and technical work. Copyright and all rights therein are retained by authors or by other copyright holders. All persons copying this information are expected to adhere to the terms and constraints invoked by each author's copyright. In most cases, these works may not be reposted without the explicit permission of the copyright holder. can upload final version FULL COPYRIGHT INFORMATION: |
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| title | Acoustic emission detection and prediction of fatigue crack propagation in composite patch repairs using neural networks |
| contributor.author | Okafor, Anthony Chukwujekwu |
| contributor.author | Singh, Navdeep |
| contributor.author | Singh, Navrag |
| contributor.deptlab | Intelligent Systems Center |
| contributor.deptlab | Mechanical & Aerospace Engineering |
| subject | crack detection |
| subject | fatigue cracks |
| subject | maintenance engineering |
| subject | neural nets |
| subject.LCSH | Acoustic emission testing. |
| subject.LCSH | Composite materials. |
| subject.LCSH | Polymers. |
| date.issued | 2007 |
| publisher | American Institute of Physics |
| identifier.citation | Okafor, A C., Navdeep Singh, and Navrag Singh. “Acoustic Emission Detection and Prediction of Fatigue Crack Propagation in Composite Patch Repairs Using Neural Networks." Review of Progress in Quantitative Nondestructive Evaluation” Volume 894, pp. 1532-1539, 2007. |
| identifier.pub.URI | |
| description.abstract | An aircraft is subjected to severe structural and aerodynamic loads during its service life. These loads can cause damage or weakening of the structure especially for aging military and civilian aircraft, thereby affecting its load carrying capabilities. Hence composite patch repairs are increasingly used to repair damaged aircraft metallic structures to restore its structural efficiency. This paper presents the results of Acoustic Emission (AE) monitoring of crack propagation in 2024-T3 Clad aluminum panels repaired with adhesively bonded octagonal, single sided boron/epoxy composite patch under tension-tension fatigue loading. Crack propagation gages were used to monitor crack initiation. The identified AE sensor features were used to train neural networks for predicting crack length. The results show that AE events are correlated with crack propagation. AE system was able to detect crack propagation even at high noise condition of 10 Hz loading; that crack propagation signals can be differentiated from matrix cracking signals that take place due to fiber breakage in the composite patch. Three back-propagation cascade feed forward networks were trained to predict crack length based on the number of fatigue cycles, AE event number, and both the Fatigue Cycles and AE events, as inputs respectively. Network using both fatigue cycles and AE event number as inputs to predict crack length gave the best results, followed by Network with fatigue cycles as input, while network with just AE events as input had a greater error. |
| type | Article - Conference proceedings |
| type.DCMIType | text |
| type.status | Final version |
| rights | This material is presented to ensure timely dissemination of scholarly and technical work. Copyright and all rights therein are retained by authors or by other copyright holders. All persons copying this information are expected to adhere to the terms and constraints invoked by each author's copyright. In most cases, these works may not be reposted without the explicit permission of the copyright holder. |
| rights | can upload final version |
| rights.URI | |
| relation.isPartOf | Review of Progress in Quantitative Nondestructive Evaluation |
| date.available | 2008-10-13T20:25:42Z |
| identifier.persist.URI |