Online Characterization of Internal Stress in Aluminum Alloys During Laser-Directed Energy Deposition

In laser-directed energy deposition (LDED) additive manufacturing, stress-induced deformation and cracking often occur unexpectedly, and, once initiated, they are difficult to remedy. To address this issue, we previously proposed the Dynamic Counter Method (DCM), which monitors internal stress based...

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Main Authors: Yi Lu, Jian Dong, Wenbo Li, Chen Wang, Rongqi Shen, Di Jiang, Yang Yi, Bin Wu, Guifang Sun, Yongkang Zhang
Format: Article
Language:English
Published: MDPI AG 2025-04-01
Series:Sensors
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Online Access:https://www.mdpi.com/1424-8220/25/8/2584
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author Yi Lu
Jian Dong
Wenbo Li
Chen Wang
Rongqi Shen
Di Jiang
Yang Yi
Bin Wu
Guifang Sun
Yongkang Zhang
author_facet Yi Lu
Jian Dong
Wenbo Li
Chen Wang
Rongqi Shen
Di Jiang
Yang Yi
Bin Wu
Guifang Sun
Yongkang Zhang
author_sort Yi Lu
collection DOAJ
description In laser-directed energy deposition (LDED) additive manufacturing, stress-induced deformation and cracking often occur unexpectedly, and, once initiated, they are difficult to remedy. To address this issue, we previously proposed the Dynamic Counter Method (DCM), which monitors internal stress based on deposition layer shrinkage, enabling real-time stress monitoring without damaging the component. To validate this method, we used AlSi10Mg material, which has a low melting point and high reflectivity, and developed a high-precision segmentation network based on DeeplabV3+ to test its ability to measure shrinkage in high-exposure images. Using a real-time reconstruction model, stress calculations were performed with DCM and thermal–mechanical coupling simulations, and the results were validated through XRD residual stress testing to confirm DCM’s accuracy in calculating internal stress in aluminum alloys. The results show that the DeeplabV3+ segmentation network accurately extracted deposition-layer contours and shrinkage information. Furthermore, DCM and thermal–mechanical coupling simulations showed good consistency in residual stress distribution, with all results falling within the experimental error range. In terms of stress evolution trends, DCM was also effective in predicting stress variations. Based on these findings, two loading strategies were proposed, and, for the first time, DCM’s application in online stress monitoring of large LDED components was validated, offering potential solutions for stress monitoring in large-scale assemblies.
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spelling doaj-art-883962d5dbf24deb85a0ee0beee975d72025-08-20T02:18:01ZengMDPI AGSensors1424-82202025-04-01258258410.3390/s25082584Online Characterization of Internal Stress in Aluminum Alloys During Laser-Directed Energy DepositionYi Lu0Jian Dong1Wenbo Li2Chen Wang3Rongqi Shen4Di Jiang5Yang Yi6Bin Wu7Guifang Sun8Yongkang Zhang9College of Mechanical and Electronic Engineering, Nanjing Forestry University, Nanjing 210037, ChinaCollege of Mechanical and Electronic Engineering, Nanjing Forestry University, Nanjing 210037, ChinaCollege of Mechanical and Electronic Engineering, Nanjing Forestry University, Nanjing 210037, ChinaCollege of Mechanical and Electronic Engineering, Nanjing Forestry University, Nanjing 210037, ChinaCollege of Mechanical and Electronic Engineering, Nanjing Forestry University, Nanjing 210037, ChinaCollege of Mechanical and Electronic Engineering, Nanjing Forestry University, Nanjing 210037, ChinaCollege of Mechanical and Electronic Engineering, Nanjing Forestry University, Nanjing 210037, ChinaCollege of Mechanical and Electronic Engineering, Nanjing Forestry University, Nanjing 210037, ChinaSchool of Mechanical Engineering, Southeast University, Nanjing 211189, ChinaSchool of Electrical and Mechanical Engineering, Guangdong University of Technology, Waihuanxi Road 100, Guangzhou 510006, ChinaIn laser-directed energy deposition (LDED) additive manufacturing, stress-induced deformation and cracking often occur unexpectedly, and, once initiated, they are difficult to remedy. To address this issue, we previously proposed the Dynamic Counter Method (DCM), which monitors internal stress based on deposition layer shrinkage, enabling real-time stress monitoring without damaging the component. To validate this method, we used AlSi10Mg material, which has a low melting point and high reflectivity, and developed a high-precision segmentation network based on DeeplabV3+ to test its ability to measure shrinkage in high-exposure images. Using a real-time reconstruction model, stress calculations were performed with DCM and thermal–mechanical coupling simulations, and the results were validated through XRD residual stress testing to confirm DCM’s accuracy in calculating internal stress in aluminum alloys. The results show that the DeeplabV3+ segmentation network accurately extracted deposition-layer contours and shrinkage information. Furthermore, DCM and thermal–mechanical coupling simulations showed good consistency in residual stress distribution, with all results falling within the experimental error range. In terms of stress evolution trends, DCM was also effective in predicting stress variations. Based on these findings, two loading strategies were proposed, and, for the first time, DCM’s application in online stress monitoring of large LDED components was validated, offering potential solutions for stress monitoring in large-scale assemblies.https://www.mdpi.com/1424-8220/25/8/2584laser-directed energy depositionnumerical simulationresidual stressonline monitoringmachine vision
spellingShingle Yi Lu
Jian Dong
Wenbo Li
Chen Wang
Rongqi Shen
Di Jiang
Yang Yi
Bin Wu
Guifang Sun
Yongkang Zhang
Online Characterization of Internal Stress in Aluminum Alloys During Laser-Directed Energy Deposition
Sensors
laser-directed energy deposition
numerical simulation
residual stress
online monitoring
machine vision
title Online Characterization of Internal Stress in Aluminum Alloys During Laser-Directed Energy Deposition
title_full Online Characterization of Internal Stress in Aluminum Alloys During Laser-Directed Energy Deposition
title_fullStr Online Characterization of Internal Stress in Aluminum Alloys During Laser-Directed Energy Deposition
title_full_unstemmed Online Characterization of Internal Stress in Aluminum Alloys During Laser-Directed Energy Deposition
title_short Online Characterization of Internal Stress in Aluminum Alloys During Laser-Directed Energy Deposition
title_sort online characterization of internal stress in aluminum alloys during laser directed energy deposition
topic laser-directed energy deposition
numerical simulation
residual stress
online monitoring
machine vision
url https://www.mdpi.com/1424-8220/25/8/2584
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