An experimental device for the simultaneous estimation of the thermal conductivity 3-D tensor and the specific heat of orthotropic composite materials

Thomas, Matthieu; Boyard, Nicolas; Lefèvre, Nicolas; Jarny, Y.; Delaunay, Didier

doi:10.1016/j.ijheatmasstransfer.2010.07.008

Cited by 49 publications

(27 citation statements)

References 26 publications

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“…Consequently, reliable and efficient methods, initially developed for mechanical models [2], are thus required for its determination. From an experimental point of view, specific devices such as classical transient laser flash (LF) [3,4], hot wire [5] methods, or a specific hot disc method [6] can be used to estimate the effective thermal properties. Another possibility is to make calculations from a representative volume element [7] of the anisotropic actual medium, knowing the thermal conductivity of each phase.…”

Section: Introductionmentioning

confidence: 99%

Transient heat conduction within periodic heterogeneous media: A space-time homogenization approach

Matine

Boyard

Legrain

et al. 2015

International Journal of Thermal Sciences

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a b s t r a c tComposite materials generally exhibit a highly anisotropic thermal behavior (due to the orientation of fibers), leading to strong difficulties to determine the thermal conductivity tensor. Two approaches can be developed for its evaluation. The first one is to carry out experimental measurements with one or several devices to get all the components of the tensor. The second one is to use predictive models based on homogenization theories from the properties and the arrangement at the microscopic scale of each component of the composite material.Following this second approach, a space-time homogenization based on the multi-scale asymptotic expansion method is first developed to model the transient heat conduction problem within periodic heterogeneous structures. The introduction of additional terms to correct the edge effects (i.e. close to the boundaries of the macroscopic domain) in the transient state is considered. We show how these transient correcting terms can be introduced and calculated, depending on the classical boundary conditions in conduction heat transfer problems. Moreover, we underline that correcting terms have also to be added to take into account "short time" effects. Furthermore, we propose to discuss numerical results of the heat transfer modeling in a Laser Flash experiment. We specifically show how the effective thermal diffusivity may be biased when edge effects are neglected in the homogenized model.

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Section: Introductionmentioning

confidence: 99%

Transient heat conduction within periodic heterogeneous media: A space-time homogenization approach

Matine

Boyard

Legrain

et al. 2015

International Journal of Thermal Sciences

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“…A transient approach, the transient plane source (TPS) technique was adopted to measure the ETC of both dry and moist non-woven fabric samples through Hot Disk TPS-2500 thermal constants analyzer at room temperature. Measurement of thermal conductivity by means of the TPS approach has been demonstrated elsewhere [40,41]. The standardized TPS technique offers its advantage in simultaneously determining thermal conductivity, thermal diffusivity and specific heat capacity from a single measurement, with marginal effort on sample preparation.…”

Section: Tps Measurementsmentioning

confidence: 99%

Investigating the effective thermal conductivity of moist fibrous fabric based on Parallel-Series model: a consideration of material’s swelling effect

Zhu

2020

Mater. Res. Express

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The aim of this work reported in the paper is to investigate the influence of moisture content on the effective thermal conductivity (ETC) of non-hygroscopic Polyethylene terephthalate (PET) and hygroscopic Viscose (VC) fabrics using Parallel-Series (P-S) thermal-electrical analogy method and TPS measurement. An equivalent porosity for hygroscopic fabric was first proposed to preserve the validity of the P-S model. The equivalent porosity is characterized by reasonably eliminating the absorbed moisture effects partly, which is embodied in enhancing heat conduction, endothermic reaction and swelling. Calculated values of the effective thermal conductivity of the two kinds of fabrics had been compared with experimental measurements. Results show that the P-S model incorporated with equivalent porosity is found to yield higher prediction accuracy than that of P-S model with parent porosity. The calibrated model can also provide a robust tool for predicting the global effective thermal conductivity of moist hygroscopic fibrous porous media. Nomenclature P-SParallel-Series ETC Effective thermal conductivity ΔP pressure difference r pore-throat radius || parallel ⊥ series T temperature

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“…Such orthotropic structures have important characteristics and several inverse analyses have been unsertaken, [16,17,19,18], for their estimation. Further, an experimental device for the simultaneous estimation of the constant thermal conductivity and the specific heat of orthotropic polymer composite materials was presented in [20]. However, in all these studies the material properties were piecewise constant or linearly space-dependent and this restricts the generality of the materials that can be identified.…”

Section: Introductionmentioning

confidence: 99%

Determination of thermal conductivity of inhomogeneous orthotropic materials from temperature measurements

Cao

Lesnic

Colaço

2018

Inverse Problems in Science and Engineering

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We consider for the first time the two-dimensional inverse determination of the thermal conductivity of inhomogeneous orthotropic materials from internal temperature measurements. The inverse problem is general and is classified as a function estimation since no prior information about the functional form of the thermal conductivity is assumed in the inverse calculation. The least-squares functional minimizing naturally the gap between the measured and computed temperature leads to a set of direct, sensitivity and adjoint problems, which have forms of direct well-posed initial boundary value problems for the heat equation, and new formulas for its gradients are derived.The conjugate gradient method (CGM) employs recursively the solution of these problems at each iteration. Stopping the iterations according to the discrepancy principle criterion yields a stable solution. The employment of the Sobolev W 1,2 -gradient is shown to result in much more robust and accurate numerical reconstructions than when the standard L 2 -gradient is used.

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An experimental device for the simultaneous estimation of the thermal conductivity 3-D tensor and the specific heat of orthotropic composite materials

Cited by 49 publications

References 26 publications

Transient heat conduction within periodic heterogeneous media: A space-time homogenization approach

Transient heat conduction within periodic heterogeneous media: A space-time homogenization approach

Investigating the effective thermal conductivity of moist fibrous fabric based on Parallel-Series model: a consideration of material’s swelling effect

Determination of thermal conductivity of inhomogeneous orthotropic materials from temperature measurements

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