A new data reduction method for pulse diffusivity measurements on coated samples

Chen, Liguo; Limarga, Andi M.; Clarke, David R.

doi:10.1016/j.commatsci.2010.07.009

Cited by 13 publications

(9 citation statements)

References 22 publications

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“…Eqs (17)- (19) express the thermal diffusivity explicitly in terms of L, the thickness of the sample, T (L, t), the rearsurface temperature rise history, T∞, the steady-state temperature rise value (7), Q∞, the total amount of heat absorbed through the front surface (6), and Q(t), the amount of heat that has been absorbed through the front surface at time t (9). For the types of functions commonly used to represent the shape of the heat pulse, which specify the finite pulse time τ , and/or peak of the pulse β (Figure 1a), the formula for the thermal diffusivity (17)-(19) simplifies significantly:…”

Section: Thermal Diffusivitymentioning

confidence: 99%

“…Hence, the above formulas provide simple finite pulse time corrections to the thermal diffusivity involving the duration and peak of the pulse. Application of the thermal diffusivity formula (17)- (19) to arbitrary pulse shapes is addressed later in Section 4.…”

Section: (21b)mentioning

confidence: 99%

“…In the discrete case, provided t N is large enough (see, e.g. [20,21], for how to estimate steady state times), the integral I T appearing in the thermal diffusivity formulas, Eqs (17)- (19) and (44)-(47), can be approximated using the trapezoidal rule [11]. For example, for the homogeneous sample:…”

Section: Verification Of Formulasmentioning

confidence: 99%

“…(i) Eqs (17)-(19) for calculating the thermal diffusivity of a homogeneous sample; and(ii) Eqs (44)-(47) for calculating the thermal diffusivity of one layer of a two-layer sample given the thermal diffusivity of the other layer. Computational results confirmed the accuracy of the derived formulas and demonstrated how the formulas can be (a)-(c) Example realisations of the rear-surface temperature rise history using low, moderate and high levels of noise.…”

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confidence: 99%

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Rear-surface integral method for calculating thermal diffusivity: Finite pulse time correction and two-layer samples

Carr

Wood

2019

International Journal of Heat and Mass Transfer

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We study methods for calculating the thermal diffusivity of solids from laser flash experiments. This experiment involves subjecting the front surface of a small sample of the material to a heat pulse and recording the resulting temperature rise on the opposite (rear) surface. Recently, a method was developed for calculating the thermal diffusivity from the rear-surface temperature rise, which was shown to produce improved estimates compared with the commonly used halftime approach. This so-called rear-surface integral method produced a formula for calculating the thermal diffusivity of homogeneous samples under the assumption that the heat pulse is instantaneously absorbed uniformly into a thin layer at the front surface. In this paper, we show how the rear-surface integral method can be applied to a more physically realistic heat flow model involving the actual heat pulse shape from the laser flash experiment. New thermal diffusivity formulas are derived for handling arbitrary pulse shapes for either a homogeneous sample or a heterogeneous sample comprising two layers of different materials. Presented numerical experiments confirm the accuracy of the new formulas and demonstrate how they can be applied to the kinds of experimental data arising from the laser flash experiment.

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Section: Thermal Diffusivitymentioning

confidence: 99%

Section: (21b)mentioning

confidence: 99%

Section: Verification Of Formulasmentioning

confidence: 99%

mentioning

confidence: 99%

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Rear-surface integral method for calculating thermal diffusivity: Finite pulse time correction and two-layer samples

Carr

Wood

2019

International Journal of Heat and Mass Transfer

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“…In more complicated cases of the physical phenomena, couplings analytical solutions, which are frequently formulated in Laplace domain and retransformed to the time domain using performant numerical inversion algorithms like the Stehfest algorithm (1970) or de Hoog’s algorithm (1982), become not effective enough in practical applications. For that reason, Chen and Clarke (2009) and Chen et al (2010) used a numerical solution-based parameter estimation technique to solve the appropriate problem. The TD was obtained from a two-layer composite specimen investigation data.…”

Section: Introductionmentioning

confidence: 99%

Inverse problem solution for a laser flash studies of a thin layer coatings

Stryczniewicz

Zmywaczyk

Panas

2017

HFF

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Purpose The paper aims to discuss the inverse heat conduction methodology in solution of a certain parameter identification problem. The problem itself concerns determination of the thermophysical properties of a thin layer coating by applying the laser flash apparatus. Design/methodology/approach The modelled laser flash diffusivity data from the three-layer sample investigation are used as input for the following parameter estimation procedure. Assuming known middle layer, i.e. substrate properties, the thermal diffusivity (TD) of the side layers’ material is determined. The estimation technique utilises the finite element method for numerical solution of the direct, 2D axisymmetric heat conduction problem. Findings The paper presents methodology developed for a three-layer sample studies and results of the estimation technique testing and evaluation based on simulated data. The multi-parametrical identification procedure results in identification of the out of plane thin layer material diffusivity from the inverse problem solution. Research limitations/implications The presentation itself is limited to numerical simulation data, but it should be underlined that the flake graphite thermophysical parameters have been utilised in numerical tests. Practical implications The developed methodology is planned to be applied in detailed experimental studies of flake graphite. Originality/value In the course of a present study, a methodology of the thin-coating layer TD determination was developed. In spite of the fact that it has been developed for the graphite coating investigation, it was planned to be universal in application to any thin–thick composite structure study.

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Thermal Diffusivity by The Laser Flash Technique

Corbin

Turriff

2012

Characterization of Materials

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Thermal diffusivity is an important material thermophysical property. The most widely used method for measuring thermal diffusivity is the laser flash technique. In this technique, a sample is placed within a controlled atmosphere furnace and subjected to a finite impulse of radiant energy on its front surface, through the use of a laser. The transport of heat through the sample, as a result of the laser impulse, causes a transient temperature rise on the rear surface of the specimen. This temperature rise is measured by an IR detector placed above the rear sample surface. The net result is a “thermogram” which is a plot of the rear‐face temperature versus time. Assuming a proper set‐up and careful experimentation, the transfer of heat under these conditions approximates one‐dimensional heat flow. Comparing the experimental data with one‐dimensional heat flow theoretical predictions, allows an estimation of thermal diffusivity. There are several methods available to determine thermal diffusivity based on experimental and theoretical comparisons. The simplest method is to determine the “half‐rise time,” t 0.5, which is the time at which the experimentally measured rear‐face temperature reaches half of its maximum value. More accurate methods use sophisticated analysis algorithms to model and fit the entire experimental thermogram curve to an ideal theoretical curve by means of a nonlinear least‐squares procedure. These approaches can include corrections that account for the fact that the experimental measurements only approximate one‐dimensional heat flow conditions. Using the thermogram curve fitting techniques, the measurement of thermal diffusivity of a range of material types including solid thermal insulators and conductors is possible. It is also possible to measure the apparent diffusivity of inhomogeneous samples such as composites and porous materials. Using two‐ and three‐layer analysis methods allows the measurement of thermal diffusivity of liquids. The layer methods can be extended to a determination of the thermal contact resistance of interfaces encountered in coated or bonded materials.

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A new data reduction method for pulse diffusivity measurements on coated samples

Cited by 13 publications

References 22 publications

Rear-surface integral method for calculating thermal diffusivity: Finite pulse time correction and two-layer samples

Rear-surface integral method for calculating thermal diffusivity: Finite pulse time correction and two-layer samples

Inverse problem solution for a laser flash studies of a thin layer coatings

Thermal Diffusivity by The Laser Flash Technique

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