Vincent Huon

Combined model of human skin - Heat transfer in the vein and tissue: experimental and numerical study

The aim of this study is to propose a combined model of heat transfer in the vein and tissue of human skin. It allows to better understand the thermomechanical behavior of the skin and its direct environment when exposed to strong thermal variations. The work is based on experimental and numerical investigations. The first experimental step consists in placing a cooled cylindrical steel bar on the skin of a human forearm and measuring the temperature change using an infrared camera. Blood circulation in the veins was seen to clearly influence heat diffusion. The second experimental step consists in measuring geometrical properties of the veins and blood velocity using an echo-Doppler probe. These experimental measurements provide a numerical model of the skin and its direct vicinity. The three-dimensional multilayer model uses Pennes equation to model biological tissue and the convective heat transport equation, to model blood. The properties of the biological materials obtained from the literature are validated by our experimentation. The numerical model is able to simulate the experimental observations, but also to estimate blood temperature and velocity in the veins.

A 3D finite element model for hyperthermia injury of blood-perfused skin.

The objective of this study is to propose a numerical model of thermal damage to the skin. This model simulates the propagation of a burn and suggests treatments to prevent it from spreading. In order to achieve this goal, we developed a 3D multi-layer finite element model of the skin coupled with a model presenting hyperthermic damage. The numerical model of the skin takes account of not only the thermal properties of various layers, but also blood perfusion and veins. The model of thermal damage is based on the Arrhenius’ law. We tested two various quick intervention treatments so as to prevent the burn from spreading. The first treatment consists of cooling the burned zone with a flow of cool water at 10°C, whereas the second solution simulates the apposition of ice on the burn. The results show that, according to the severity of the burn, the second treatment seems to be the most appropriate. Moreover, our model opens interesting prospects in the analysis of hyperthermic damage.

Influence of gravity on the skin thermal behavior: experimental study using dynamic infrared thermography

To better understand the thermomechanical behavior of the skin and its direct environment, we present an experimental study using dynamic infrared thermography. This experimental study aims to highlight quantitatively some effects of blood flow on the heat diffusion.

Mise en évidence et quantification des couplages thermomécaniques réversibles et irréversibles dans les bétons sains et endommagés par des cycles gel-dégel

A partir de lobservation fine par thermographie infrarouge des phenomenes thermiques mis en jeu lors de sollicitations de compression quasi-statiques, sont identifiees et quantifiees lincidence de leffet thermoelastique et celle de la dissipation intrinseque associee a letat dendommagement dun beton ayant subi des cycles gel-degel.

Comportement thermomécanique d'un béton ordinaire en compression cyclée: expérience et modélisation

Resume Les faibles phenomenes thermiques apparaissant lors dessais de compression sur un beton ordinaire ont pu etre observes par thermographie infrarouge. Pour leur modelisation et leur interpretation, il est propose une extension thermomecanique du modele elastique endommageable de M. Fremond et B. Nedjar. Elle permet un dialogue interessant entre les resultats experimentaux et ceux obtenus par simulation numerique.

Mise en évidence par granularité en lumière blanche de phénomènes de multilocalisation de la déformation pour les bétons de poudres réactives sollicités en traction

Resume Le comportement en traction dun beton de poudres reactives est etudie a partir dobservations cinematiques par granularite en lumiere blanche fondees sur une technique dintercorrelation dimages. Les mesures mettent en evidence pour des BPR suffisamment fibres, a la difference des betons ordinaires, lapparition systematique de plusieurs zones de localisation de la deformation et le role des fibres dans la redistribution des efforts au voisinage dune zone fissuree.