Detection of Internal Defects in Concrete Using Delay Multiply and Sum-Enhanced Synthetic Aperture Focusing Technique

Traditional techniques for detecting internal defects in concrete are limited by the weak directivity of ultrasonic waves, significant signal attenuation, and low imaging contrast. This paper presents an improved synthetic aperture focusing technique (SAFT) enhanced by the Delay Multiply and Sum (DM...

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Main Authors: Feng Li, Sheng-Kui Di, Jing Zhang, Dong Yang, Yao Pei, Xiao-Ying Wang
Format: Article
Language:English
Published: MDPI AG 2025-05-01
Series:Buildings
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Online Access:https://www.mdpi.com/2075-5309/15/11/1887
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author Feng Li
Sheng-Kui Di
Jing Zhang
Dong Yang
Yao Pei
Xiao-Ying Wang
author_facet Feng Li
Sheng-Kui Di
Jing Zhang
Dong Yang
Yao Pei
Xiao-Ying Wang
author_sort Feng Li
collection DOAJ
description Traditional techniques for detecting internal defects in concrete are limited by the weak directivity of ultrasonic waves, significant signal attenuation, and low imaging contrast. This paper presents an improved synthetic aperture focusing technique (SAFT) enhanced by the Delay Multiply and Sum (DMAS) algorithm to address these limitations and improve both the resolution and signal-to-noise ratio. The proposed method sequentially transmits and receives ultrasonic waves through an array of transducers, and applies DMAS-based nonlinear beam-forming to enhance image sharpness and contrast. Its effectiveness was validated through finite element simulations and experimental tests using three precast concrete specimens with artificial defects (specimen size: 240 mm × 300 mm × 100 mm). Compared with the conventional SAFT, the proposed method improves image contrast by approximately 40%, with clearer defect boundaries and a vertical positioning error of less than ±5 mm. This demonstrates the method’s promising potential for practical applications in internal defect visualization of concrete structures.
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spelling doaj-art-48031e6fb2c74b3681c8a2b78a6a71712025-08-20T03:11:18ZengMDPI AGBuildings2075-53092025-05-011511188710.3390/buildings15111887Detection of Internal Defects in Concrete Using Delay Multiply and Sum-Enhanced Synthetic Aperture Focusing TechniqueFeng Li0Sheng-Kui Di1Jing Zhang2Dong Yang3Yao Pei4Xiao-Ying Wang5School of Civil Engineering, Lanzhou Jiaotong University, Lanzhou 730070, ChinaSchool of Civil Engineering, Lanzhou Jiaotong University, Lanzhou 730070, ChinaCollege of Civil Engineering, Xiangtan University, Xiangtan 411105, ChinaEarthquake Engineering Research & Test Center (EERTC), Guangzhou University, Guangzhou 510405, ChinaDepartment of Civil Engineering, Hefei University of Technology, Hefei 230009, ChinaGansu Wantai Construction Engineering Co., Ltd., Lanzhou 730030, ChinaTraditional techniques for detecting internal defects in concrete are limited by the weak directivity of ultrasonic waves, significant signal attenuation, and low imaging contrast. This paper presents an improved synthetic aperture focusing technique (SAFT) enhanced by the Delay Multiply and Sum (DMAS) algorithm to address these limitations and improve both the resolution and signal-to-noise ratio. The proposed method sequentially transmits and receives ultrasonic waves through an array of transducers, and applies DMAS-based nonlinear beam-forming to enhance image sharpness and contrast. Its effectiveness was validated through finite element simulations and experimental tests using three precast concrete specimens with artificial defects (specimen size: 240 mm × 300 mm × 100 mm). Compared with the conventional SAFT, the proposed method improves image contrast by approximately 40%, with clearer defect boundaries and a vertical positioning error of less than ±5 mm. This demonstrates the method’s promising potential for practical applications in internal defect visualization of concrete structures.https://www.mdpi.com/2075-5309/15/11/1887synthetic aperture focusing techniquedelay multiply and sumconcrete internal-defect imagingsensor arraynon-destructive testing
spellingShingle Feng Li
Sheng-Kui Di
Jing Zhang
Dong Yang
Yao Pei
Xiao-Ying Wang
Detection of Internal Defects in Concrete Using Delay Multiply and Sum-Enhanced Synthetic Aperture Focusing Technique
Buildings
synthetic aperture focusing technique
delay multiply and sum
concrete internal-defect imaging
sensor array
non-destructive testing
title Detection of Internal Defects in Concrete Using Delay Multiply and Sum-Enhanced Synthetic Aperture Focusing Technique
title_full Detection of Internal Defects in Concrete Using Delay Multiply and Sum-Enhanced Synthetic Aperture Focusing Technique
title_fullStr Detection of Internal Defects in Concrete Using Delay Multiply and Sum-Enhanced Synthetic Aperture Focusing Technique
title_full_unstemmed Detection of Internal Defects in Concrete Using Delay Multiply and Sum-Enhanced Synthetic Aperture Focusing Technique
title_short Detection of Internal Defects in Concrete Using Delay Multiply and Sum-Enhanced Synthetic Aperture Focusing Technique
title_sort detection of internal defects in concrete using delay multiply and sum enhanced synthetic aperture focusing technique
topic synthetic aperture focusing technique
delay multiply and sum
concrete internal-defect imaging
sensor array
non-destructive testing
url https://www.mdpi.com/2075-5309/15/11/1887
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