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Approach of the measurement of thermal diffusivity of mural paintings by front face photothermal radiometry
| Content Provider | Semantic Scholar |
|---|---|
| Author | Candoré, Jean Charles Bodnar, Jean Luc Detalle, Vincent Rémy, Benjamin Grossel, Philippe |
| Copyright Year | 2010 |
| Abstract | This paper deals with the approach of the possibilities of the front face photothermal thermography to measure the longitudinal thermal diffusivity of a mural painting. We present at first the principle of the method of measure based on the use coupled of transformed integrals and thermal quadruples. We show then the feasibility of the method by means of numerical simulation. We present then the experimental device implemented for the study. We show finally, by means of the experimental study of a sample of plaster, which the photothermal method allows in a particular case, a good estimation of the parameter longitudinal thermal diffusivity. Within the framework of the assistance to restoration of mural painting, our laboratory works since about ten year on the detection of detachment and air pocket situated in frescoes. The front face photothermal thermography, has already allowed us to detect, in situ, detachment situated in the Saint Christopher of the “Campana” collection of “Louvre”, in walls painted of the church Saint Florentin of Bonnet, in ceilings painted of abbey of “Saint Savin sur Gartempe” (classified in the UNESCO world heritage) and finally in the frescoes Cocteau of the vault “Saint Pierre” of “Villefranche sur Mer” [1-3 ]. These qualitative studies being positive, they push us now to study the possibilities of the photothermal method in characterization of the defects. Later, the objective is to determine both the area of the defect but also the depth in which it is situated. For it we intend to proceed by an adjustment theory / experiment with the use of methods of inverse techniques of the type levenberg marquardt [4]. To feed the model evoked previously, it is necessary to know the thermophysical properties of the studied materials. Two solutions were offered to us: either appeal to bibliographical values that is to develop a method of measure of diffusivity usable in situ. For reasons of appropriate life of materials (ageing, presence of humidity, manufacturing processes, environment), it is the second solution that we chose to implement. To lead to these measures of diffusivity, we had even there two solutions: either take a sample of work of art or implement a classic method of measure of this thermophysical parameter (method flash [5]), or develop a useful method in situ and non-destructive for the studied mural painting. For reasons of good preservation of the works of art, it is this last option we chose to implement. The thickness of the couple coats - wall composing the mural painting being often of several tens centimeters, a measure of transverse thermal diffusivity is often impossible. We thus chose to develop a method of measure of longitudinal thermal diffusivity of the work of art. It is this method we present here. We present at first the principle of the method of measure, based on the use coupled of integral transformations and the quadrupole method [6]. We show then the feasibility of the method by means of numerical simulation. We present then the experimental device developed for the study. We show finally, the method gives access to a good estimation of the longitudinal diffusivity of a sample of plaster. 2. Principle of in situ measure of longitudinal thermal diffusivity |
| Starting Page | 012094 |
| Ending Page | 012094 |
| Page Count | 1 |
| File Format | PDF HTM / HTML |
| DOI | 10.1088/1742-6596/214/1/012094 |
| Volume Number | 214 |
| Alternate Webpage(s) | http://qirt.gel.ulaval.ca/archives/qirt2010/papers/QIRT%202010-029.pdf |
| Alternate Webpage(s) | https://www.ndt.net/article/qirt2010/papers/qirt2010-029.pdf |
| Alternate Webpage(s) | https://doi.org/10.1088/1742-6596%2F214%2F1%2F012094 |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
