Effective Thermal Diffusivity Measurement Using Through-Transmission Pulsed Thermography: Extending the Current Practice by Incorporating Multi-Parameter Optimisation

Through-transmission pulsed thermography (PT) is an effective non-destructive testing (NDT) technique for assessing material thermal diffusivity. However, the current literature indicates that the technique has lagged behind the reflection mode in terms of technique development despite it offering b...

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Main Authors: Zain Ali, Sri Addepalli, Yifan Zhao
Format: Article
Language:English
Published: MDPI AG 2025-02-01
Series:Sensors
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Online Access:https://www.mdpi.com/1424-8220/25/4/1139
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author Zain Ali
Sri Addepalli
Yifan Zhao
author_facet Zain Ali
Sri Addepalli
Yifan Zhao
author_sort Zain Ali
collection DOAJ
description Through-transmission pulsed thermography (PT) is an effective non-destructive testing (NDT) technique for assessing material thermal diffusivity. However, the current literature indicates that the technique has lagged behind the reflection mode in terms of technique development despite it offering better defect resolution and the detection of deeper subsurface defects. Existing thermal diffusivity measurement systems require costly setups, including temperature-controlled chambers, multiple calibrations, and strict sample size requirements. This study presents a simple and repeatable methodology for determining thermal diffusivity in a laboratory setting using the through-transmission approach by incorporating both finite element analysis (FEA) and laboratory experiments. A full-factorial design of experiments (DOE) was implemented to determine the optimum flash energy and sample thickness for a reliable estimation of thermal diffusivity. The thermal diffusivity is estimated using the already established Parker’s half-rise equation and the recently developed new least squares fitting (NLSF) algorithm. The latter not only estimates thermal diffusivity but also provides estimates for the input flash energy, reflection coefficient, and the time delay in data capture following the flash event. The results show that the NLSF is less susceptible to noise and offers more repeatable values for thermal diffusivity measurements compared to Parker, thereby establishing it as a more efficient and reliable technique.
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spelling doaj-art-c21f27bdce044141afe4458e99640b752025-08-20T02:03:27ZengMDPI AGSensors1424-82202025-02-01254113910.3390/s25041139Effective Thermal Diffusivity Measurement Using Through-Transmission Pulsed Thermography: Extending the Current Practice by Incorporating Multi-Parameter OptimisationZain Ali0Sri Addepalli1Yifan Zhao2Faculty of Engineering and Applied Sciences (FEAS), Cranfield University, Cranfield MK43 0AL, UKFaculty of Engineering and Applied Sciences (FEAS), Cranfield University, Cranfield MK43 0AL, UKFaculty of Engineering and Applied Sciences (FEAS), Cranfield University, Cranfield MK43 0AL, UKThrough-transmission pulsed thermography (PT) is an effective non-destructive testing (NDT) technique for assessing material thermal diffusivity. However, the current literature indicates that the technique has lagged behind the reflection mode in terms of technique development despite it offering better defect resolution and the detection of deeper subsurface defects. Existing thermal diffusivity measurement systems require costly setups, including temperature-controlled chambers, multiple calibrations, and strict sample size requirements. This study presents a simple and repeatable methodology for determining thermal diffusivity in a laboratory setting using the through-transmission approach by incorporating both finite element analysis (FEA) and laboratory experiments. A full-factorial design of experiments (DOE) was implemented to determine the optimum flash energy and sample thickness for a reliable estimation of thermal diffusivity. The thermal diffusivity is estimated using the already established Parker’s half-rise equation and the recently developed new least squares fitting (NLSF) algorithm. The latter not only estimates thermal diffusivity but also provides estimates for the input flash energy, reflection coefficient, and the time delay in data capture following the flash event. The results show that the NLSF is less susceptible to noise and offers more repeatable values for thermal diffusivity measurements compared to Parker, thereby establishing it as a more efficient and reliable technique.https://www.mdpi.com/1424-8220/25/4/1139infrared thermographythrough transmissionthermal diffusivityfull-factorial designfinite element analysispulsed thermography
spellingShingle Zain Ali
Sri Addepalli
Yifan Zhao
Effective Thermal Diffusivity Measurement Using Through-Transmission Pulsed Thermography: Extending the Current Practice by Incorporating Multi-Parameter Optimisation
Sensors
infrared thermography
through transmission
thermal diffusivity
full-factorial design
finite element analysis
pulsed thermography
title Effective Thermal Diffusivity Measurement Using Through-Transmission Pulsed Thermography: Extending the Current Practice by Incorporating Multi-Parameter Optimisation
title_full Effective Thermal Diffusivity Measurement Using Through-Transmission Pulsed Thermography: Extending the Current Practice by Incorporating Multi-Parameter Optimisation
title_fullStr Effective Thermal Diffusivity Measurement Using Through-Transmission Pulsed Thermography: Extending the Current Practice by Incorporating Multi-Parameter Optimisation
title_full_unstemmed Effective Thermal Diffusivity Measurement Using Through-Transmission Pulsed Thermography: Extending the Current Practice by Incorporating Multi-Parameter Optimisation
title_short Effective Thermal Diffusivity Measurement Using Through-Transmission Pulsed Thermography: Extending the Current Practice by Incorporating Multi-Parameter Optimisation
title_sort effective thermal diffusivity measurement using through transmission pulsed thermography extending the current practice by incorporating multi parameter optimisation
topic infrared thermography
through transmission
thermal diffusivity
full-factorial design
finite element analysis
pulsed thermography
url https://www.mdpi.com/1424-8220/25/4/1139
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AT sriaddepalli effectivethermaldiffusivitymeasurementusingthroughtransmissionpulsedthermographyextendingthecurrentpracticebyincorporatingmultiparameteroptimisation
AT yifanzhao effectivethermaldiffusivitymeasurementusingthroughtransmissionpulsedthermographyextendingthecurrentpracticebyincorporatingmultiparameteroptimisation