MASTER « Techniques Avancées en Calcul de Structures »
Année universitaire 2014-2015
PROPOSITION DE SUJET DE STAGE
Titre du mémoire :
Modélisation 3D de la peau sous ondes électromagnétiques
Responsables du mémoire : Elisa Budyn
[email protected]
Mots clé : flux thermique, reconstruction 3D, multi-échelles, homogénéisation
Descriptif : Skin is the largest organ in the human body. It is composed of multiple protective and
sensory layers: the epidermis and the dermis that are first cut during any surgery procedures but also
the first layer of the body that is exposed the environment. Besides its mechano-sensing function of
touch, pressure, pain and heat, skin is part of the adaptive immune system and contributes to the
body temperature regulation. Any agression on the tissue such as long-term low heating produced by
electromagnetic radiation can potentially affect its homeostasis.
In the epidermis four strata (corneum, granulosum, spinosum and germinativum), keratinocyte
stem cells germinate to undergo differentiation until cornification into corneocytes attached by corneodesmosomes. Beneath, the two strata of the dermis (papillare and reticulare) are composed of
collagen-elastin fibrous connective tissues produced by fibroblasts immersed in the hydrous ground
substance containing proteins and proteoglycans. In the papillary region the areolar connective tissue
is loose and in the reticular region the connective tissue is dense and irregular. Collagenous fibrous
tissue surrounds cutaneous extensions such as : hair follicles, sweat glands, sebaceous glands,
apocrine glands, nerves, Parcinian and Meissner corpuscles, lymphatic vessels and blood vessels.
The hypodermis below produced by adipocytes is attached to the muscles and bones. Skin tissue is
therefore a complex 3D structure containing multiple biological phases with highly irregular coutours
of which the complexity should be included in the numerical model to deliver biologically relevant
information.
Closer observations of the reticular dermal tissue reveal some variations of the fibrous network
near the different skin extensions. The local densities and the orientations of the collagen and elastin
fibers change through the dermis extra cellular matrix (ECM). The fibers of the ECM are produced
and maintained by migrating fibroblasts that are mechano-sensitive cells that detect and respond to
mechanical load. Local heating due to electromagnetic radiation will modify the keratin lamellar
structure of the epidermis and produce cross-linking in the fibrous organisation of the dermis.
Homogeneisation of the varying properties of the dermous tissue could represent the thermochemical changes due to electromagnetic radiation exposure. The constitutive models of the
homogenized skin multiple scales can be implemented in the ABAQUS discretization.
Dans le cadre de ce stage en collaboration avec le centre DMRT du College de Dentistry de
l’University of Illinois at Chicago, on se propose d’étudier l’impact thermique des ondes radio du
spectre électromagnétique sur le tissu cutané.
Travail proposé :
- Etude bibliographique : tissu cutané et ses extensions, modèle thermo-mécanique de la peau,
ondes radio, homogénéisation hiérarchique des structures elliptiques et fibreuses.
- Mise en place d’un modèle 3D du tissu cutané humain et de ses extensions dans ABAQUS.
Caracterisation des RVE des phases présentes pour développer leurs homogénéisations
respectives.
- Modélisation de flux thermique créé par des puissances inférieures au Watt sur des temps
d’application longs.
Lieu du stage : LMT-Cachan, secteur « Structures & Systèmes »