Imaging wood defects using air coupled ferroelectret ultrasonic transducers in reflection mode

Vössing, Konrad J.; Gaal, Mate; Niederleithinger, Ernst

doi:10.1016/j.conbuildmat.2020.118032

Cited by 12 publications

(11 citation statements)

References 21 publications

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“…used the Python language to write an upper computer software that can automate non-contact ultrasonic detection of wood defects. Besides, the use of some new material sensors can improve the signal-to-noise ratio and thus make the ACU technique detecting defects more accurately (Vössing et al 2020). However, ultrasonic methods for detecting wood defects have limitations (Vössing and Niederleithinger 2018).…”

Section: Ultrasound-based Internal Defect Detection Methodsmentioning

confidence: 99%

Review of the current state of application of wood defect recognition technology

Chen

Sun

Ren

et al. 2022

BioRes

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Wood utilisation is an important factor affecting production costs, but the combined utilisation rate of wood is generally only 50 to 70%. During the production process, the rejection scheme of wood defects is one of the most important factors affecting the wood yield. This paper provides an overview of the main wood defects affecting wood quality, introduces techniques for detecting and identifying wood defects using different technologies, highlights the more widely used image recognition-based wood surface defect identification methods, and presents three advanced wood defect detection and identification equipment. In view of the relatively fixed wood defect recognition requirements in wood processing production, it is proposed that wood defect recognition technology should be further developed toward deep learning to improve the accuracy and efficiency of wood defect recognition.

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Section: Ultrasound-based Internal Defect Detection Methodsmentioning

confidence: 99%

Review of the current state of application of wood defect recognition technology

Chen

Sun

Ren

et al. 2022

BioRes

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“…In the current research this frequency is equal to 40 kHz, however scientists used transducers with different frequency values. In paper [11] the range of 90 -200 kHz was considered, authors of [4] used 1 MHz-based ACT and in [12] the investigations of ACT performance in the frequency range of 750 kHz -2 MHz were conducted. Along with the analysis of Lamb waves propagation, it is possible to detect different defects in the analyzed structures.…”

Section: Introductionmentioning

confidence: 99%

Optimal slope angles of the air-coupled transducer from viewpoint of the effective Lamb waves propagation in different materials

Mindykowski¹,

Wandowski²,

Radzieński³

et al. 2022

eJNDT

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Air-coupled transducers (ACT) allow for non-contact generation of acoustic waves which can be later transferred into elastic waves due to interactions with the solid specimen. Proper slope of the ACT in relation to the investigated specimen surface during acoustic waves generation is important as it leads to the possibility of generation of desired Lamb wave modes in the form of elastic waves with selected propagation velocity values. Effective generation of these modes ease the analysis of elastic waves propagation in specimens, simultaneously helping in detection of material defects if they exist. The attempt to determine optimal slope angles was undertaken in case of aluminum (Al), carbon fiber-reinforced polymer (CFRP) and glass fiber-reinforced polymer (GFRP) plate-like structure. Due to relatively low excitation frequency of the used ACT (40 kHz) the investigation was focused on the slope angles referred to the generation of zero-order modes - antisymmetric A0 and symmetric S0. In CFRP plate case the issue of efficient generation of shear horizontal (SH0) wave mode was additionally considered. In Al and CFRP plate case optimal slope angles were considered numerically (Comsol, Matlab) and experimentally (lab investigations, Matlab) while in GFRP plate case they were estimated experimentally. Although not all of the slope angles were successfully determined within different approaches, the results helped to form some interesting conclusions. After determination of the slope angles the performance of sloped/non-sloped ACT was compared in full wavefield measurements (comparison of signal energy maps calculated with the usage of root mean square (RMS) formula). Recommendations for further work were depicted within the summary section.

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“…The stress wave-based method usually utilizes wave speed as an indicator to obtain internal information since the existence of internal holes would rapidly decrease wave speed. [10][11][12][13] Some researchers use the variation of wave speed to conduct internal imaging. 14,15 However, this method requires sensor installation prior to each local test, which greatly limits its application for real projects.…”

Section: Introductionmentioning

confidence: 99%

An innovative deep neural network–based approach for internal cavity detection of timber columns using percussion sound

Chen

Xiong

Sang

et al. 2021

Structural Health Monitoring

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Timber structures have been a dominant form of construction throughout most of history and continued to serve as a widely used staple of civil infrastructure in the modern era. As a natural material, wood is prone to termite damages, which often cause internal cavities for timber structures. Since internal cavities are invisible and greatly weaken structural load-bearing capacity, an effective method to timber internal cavity detection is of great importance to ensure structural safety. This article proposes an innovative deep neural network (DNN)–based approach for internal cavity detection of timber columns using percussion sound. The influence mechanism of percussion sound with the volume change of internal cavity was studied through theoretical and numerical analysis. A series of percussion tests on timber column specimens with different cavity volumes and environmental variations were conducted to validate the feasibility of the proposed DNN-based approach. Experimental results show high accuracy and generality for cavity severity identification regardless of percussion location, column section shape, and environmental effects, implying great potentials of the proposed approach as a fast tool for determining internal cavity of timber structures in field applications.

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Imaging wood defects using air coupled ferroelectret ultrasonic transducers in reflection mode

Cited by 12 publications

References 21 publications

Review of the current state of application of wood defect recognition technology

Review of the current state of application of wood defect recognition technology

Optimal slope angles of the air-coupled transducer from viewpoint of the effective Lamb waves propagation in different materials

An innovative deep neural network–based approach for internal cavity detection of timber columns using percussion sound

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