scholarly journals Quantifying Uncertainty in Pulsed Thermographic Inspection by Analysing the Thermal Diffusivity Measurements of Metals and Composites

Sensors ◽  
2021 ◽  
Vol 21 (16) ◽  
pp. 5480
Author(s):  
Sri Addepalli ◽  
Yifan Zhao ◽  
John Ahmet Erkoyuncu ◽  
Rajkumar Roy
Keyword(s):  
Thermal Diffusivity ◽  
Standard Deviation ◽  
Surface Damage ◽  
Post Processing ◽  
Thermal Diffusivity Measurement ◽  
Large Variability ◽  
Reinforced Plastics ◽  
Diffusivity Measurements ◽  
Relative Standard ◽  
Processing Algorithms

Pulsed thermography has been used significantly over the years to detect near and sub-surface damage in both metals and composites. Where most of the research has been in either improving the detectability and/or its applicability to specific parts and scenarios, efforts to analyse and establish the level of uncertainty in the measurements have been very limited. This paper presents the analysis of multiple uncertainties associated with thermographic measurements under multiple scenarios such as the choice of post-processing algorithms; multiple flash power settings; and repeat tests on four materials, i.e., aluminium, steel, carbon-fibre reinforced plastics (CFRP) and glass-fibre reinforced plastics (GFRP). Thermal diffusivity measurement has been used as the parameter to determine the uncertainty associated with all the above categories. The results have been computed and represented in the form of a relative standard deviation (RSD) ratio in all cases, where the RSD is the ratio of standard deviation to the mean. The results clearly indicate that the thermal diffusivity measurements show a large RSD due to the post-processing algorithms in the case of steel and a large variability when it comes to assessing the GFRP laminates.

scholarly journals Uncertainty Assessment for Very High Temperature Thermal Diffusivity Measurements on Molybdenum, Tungsten and Isotropic Graphite

2021 ◽  
Vol 43 (1) ◽  
Author(s):  
Bruno Hay ◽  
Olivier Beaumont ◽  
Guillaume Failleau ◽  
Nolwenn Fleurence ◽  
Marc Grelard ◽  
...  
Keyword(s):  
High Temperature ◽  
Thermal Diffusivity ◽  
Laser Flash ◽  
Uncertainty Assessment ◽  
National Metrology Institute ◽  
Thermal Diffusivity Measurement ◽  
Uncertainty In Measurement ◽  
Diffusivity Measurements ◽  
Very High ◽  
Isotropic Graphite

AbstractThe French National Metrology Institute LNE has improved its homemade laser flash apparatus in order to perform accurate and reliable measurements of thermal diffusivity of homogeneous solid materials at very high temperature. The inductive furnace and the associated infrared (IR) detection systems have been modified and a specific procedure for the in situ calibration of the used radiation thermometers has been developed. This new configuration of the LNE’s diffusivimeter has been then applied for measuring the thermal diffusivity of molybdenum up to 2200 °C, tungsten up to 2400 °C and isotropic graphite up to 3000 °C. Uncertainties associated with these high temperature thermal diffusivity measurements have been assessed for the first time according to the principles of the “Guide to the Expression of Uncertainty in Measurement” (GUM). Detailed uncertainty budgets are here presented in the case of the isotropic graphite for measurements performed at 1000 °C, 2000 °C and 3000 °C. The relative expanded uncertainty (coverage factor k = 2) of the thermal diffusivity measurement is estimated to be between 3 % and 5 % in the whole temperature range for the three investigated refractory materials.

Thermal Diffusivity Measurement in Solids by means of the Photoacoustic Technique

2009 ◽  
Vol 1242 ◽  
Author(s):  
José B. Rojas-Trigos ◽  
A. Calderón ◽  
E. Marín
Keyword(s):  
Experimental Data ◽  
Gallium Arsenide ◽  
Thermal Diffusivity ◽  
Heat Source ◽  
Photoacoustic Technique ◽  
Heat Transmission ◽  
Thermal Diffusivity Measurement ◽  
Model Based ◽  
Diffusivity Measurement ◽  
Diffusivity Measurements

ABSTRACTWe report thermal diffusivity measurements for samples of silicon, gallium arsenide and cupper by means of the photoacoustic technique in a heat transmission configuration in order to obtain a comparison between the results obtained with the use of the conventional RG-model and our SP-model (based in a square periodical heat source) in the fitting process to the experimental data. Our results show that our SP-model is accurate to obtain a good fitting with the experimental data and it improves notably the results obtained with the RG-model.

scholarly journals Micro-Scale Fatigue Damage Assessment of CFRP Laminates Using Lock-in Thermography

2021 ◽  
Vol 8 (1) ◽  
pp. 2
Author(s):  
Ryohei Fujita ◽  
Kotaro Katsukura ◽  
Hosei Nagano
Keyword(s):  
Thermal Diffusivity ◽  
Fatigue Damage ◽  
Damage Assessment ◽  
Assessment Method ◽  
Thermal Diffusivity Measurement ◽  
Cfrp Laminates ◽  
Micro Scale ◽  
Reinforced Plastics ◽  
Diffusivity Measurement ◽  
Lock In

This study proposes a new micro-scale damage assessment method of laminated carbon fiber-reinforced plastics based on the thermal diffusivity measurement. This measurement was conducted by the laser-spot-periodic-heating method using lock-in thermography. Measured samples were subjected to the tension fatigue test at a relatively low load and high cycle. As a result, the thermal diffusivity showed a decreasing trend with an increase in the load cycles. It was shown that this method can detect the effect of the minute fatigue damage at a level that cannot be seen with a microscope.

An Automated Procedure for the Determination of Ammonia in Tobacco

1972 ◽  
Vol 6 (4) ◽  
Author(s):  
P.F. Collins ◽  
W.W. Lawrence ◽  
J.F. Williams
Keyword(s):  
Standard Deviation ◽  
Relative Standard Deviation ◽  
Distillation Method ◽  
Relative Standard ◽  
Tobacco Sample ◽  
Automated Determination

AbstractA procedure for the automated determination of ammonia in tobacco has been developed. Ammonia is extracted from the ground tobacco sample with water and is determined with a Technicon Auto Analyser system which employs separation of the ammonia through volatilization followed by colourimetry using the phenate-hypochlorite reaction. The procedure has been applied to a variety of tobaccos containing from 0.02 to 0.5 % ammonia with an overall relative standard deviation of 2 %. The accuracy of the procedure as judged by recovery tests and by comparison to a manual distillation method is considered adequate

How Certain Are the Reported Ionic Conductivities of Thiophosphate-Based Solid Electrolytes? an Interlaboratory Study

2020 ◽  
Author(s):  
Saneyuki Ohno ◽  
Tim Bernges ◽  
Johannes Buchheim ◽  
Marc Duchardt ◽  
Anna-Katharina Hatz ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Ionic Conductivity ◽  
Relative Standard Deviation ◽  
Solid Electrolytes ◽  
Ionic Conductivities ◽  
Ionic Conductors ◽  
Energy Storage Devices ◽  
Activation Barriers ◽  
Storage Devices ◽  
Relative Standard

<p>Owing to highly conductive solid ionic conductors, all-solid-state batteries attract significant attention as promising next-generation energy storage devices. A lot of research is invested in the search and optimization of solid electrolytes with higher ionic conductivity. However, a systematic study of an <i>interlaboratory reproducibility</i> of measured ionic conductivities and activation energies is missing, making the comparison of absolute values in literature challenging. In this study, we perform an uncertainty evaluation via a Round Robin approach using different Li-argyrodites exhibiting orders of magnitude different ionic conductivities as reference materials. Identical samples are distributed to different research laboratories and the conductivities and activation barriers are measured by impedance spectroscopy. The results show large ranges of up to 4.5 mScm<sup>-1</sup> in the measured total ionic conductivity (1.3 – 5.8 mScm<sup>-1</sup> for the highest conducting sample, relative standard deviation 35 – 50% across all samples) and up to 128 meV for the activation barriers (198 – 326 meV, relative standard deviation 5 – 15%, across all samples), presenting the necessity of a more rigorous methodology including further collaborations within the community and multiplicate measurements.</p>

Thermal Diffusivity Measurement of a NiTi Shape Memory Alloy Using a Periodic Temperature Field

2021 ◽  
Vol 42 (10) ◽  
Author(s):  
José Ricardo Ferreira-Oliveira ◽  
Paulo César Sales da Silva ◽  
Luiz Roberto Rocha de Lucena ◽  
Rômulo Pierre Batista dos Reis ◽  
Carlos José de Araújo ◽  
...  
Keyword(s):  
Temperature Field ◽  
Thermal Diffusivity ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Niti Shape Memory Alloy ◽  
Thermal Diffusivity Measurement ◽  
Diffusivity Measurement ◽  
Periodic Temperature

scholarly journals Indirect and Direct Determination of the Casein Content of Milk by Kjeldahl Nitrogen Analysis: Collaborative Study

1998 ◽  
Vol 81 (4) ◽  
pp. 763-774 ◽  
Author(s):  
Joanna M Lynch ◽  
David M Barbano ◽  
J Richard Fleming
Keyword(s):  
Standard Deviation ◽  
Nitrogen Content ◽  
Relative Standard Deviation ◽  
Collaborative Study ◽  
Direct Determination ◽  
Raw Milk ◽  
Method Performance ◽  
Relative Standard ◽  
Milk Casein

Abstract The classic method for determination of milk casein is based on precipitation of casein at pH 4.6. Precipitated milk casein is removed by filtration and the nitrogen content of either the precipitate (direct casein method) or filtrate (noncasein nitrogen; NCN) is determined by Kjeldahl analysis. For the indirect casein method, milk total nitrogen (TN; Method 991.20) is also determined and casein is calculated as TN minus NCN. Ten laboratories tested 9 pairs of blind duplicate raw milk materials with a casein range of 2.42- 3.05℅ by both the direct and indirect casein methods. Statistical performance expressed in protein equivalents (nitrogen ⨯ 6.38) with invalid and outlier data removed was as follows: NCN method (wt%), mean = 0.762, sr = 0.010, SR = 0.016, repeatability relative standard deviation (RSDr) = 1.287℅, reproducibility relative standard deviation (RSDR) = 2.146%; indirect casein method (wt℅), mean = 2.585, repeatability = 0.015, reproducibility = 0.022, RSDr = 0.560℅, RSDR = 0.841; direct casein method (wt℅), mean = 2.575, sr = 0.015, sR = 0.025, RSDr = 0.597℅, RSDR = 0.988℅. Method performance was acceptable and comparable to similar Kjeldahl methods for determining nitrogen content of milk (Methods 991.20, 991.21,991.22, 991.23). The direct casein, indirect casein, and noncasein nitrogen methods have been adopted by AOAC INTERNATIONAL.

ChemInform Abstract: Thermal Diffusivity Measurement of Uranium-Thorium-Zirconium Hydride.

ChemInform ◽  
2001 ◽  
Vol 32 (15) ◽  
pp. no-no
Author(s):  
B. Tsuchiya ◽  
J. Huang ◽  
K. Konashi ◽  
W. Saiki ◽  
T. Onoue ◽  
...  
Keyword(s):  
Thermal Diffusivity ◽  
Zirconium Hydride ◽  
Thermal Diffusivity Measurement ◽  
Diffusivity Measurement
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