Publicação
Experimental and numerical characterization of the viscoelastic behaviour of cartilages and soft tissues of the human nose
| Resumo: | The facial plastic surgery, and particularly the area of rhinoplasty, is undoubtedly a growing up market. Surgical techniques have been evolving to respond to very specific patient desires not only for functional reasons, but also to resolve aesthetic issues. Actually, it is moving plenty of money around the world, being a great scientific and commercial opportunity among researchers. The human nose is composed of three major portions separated by two well-defined regions of transition (K-area and S-area) that are very complicated to deal with in postoperative periods. The viscoelastic behaviour of soft biological tissues, especially that of nasal cartilages and adjacent subcutaneous/fatty tissues, is barely known. There are no studies on the viscoelastic characterization of the mechanical properties of nasal septum (NS), upper lateral cartilages (ULC), and lower lateral cartilages (LLC) in creep and relaxation (basic viscoelasticity features) neither on the determination of frequency- and temperature-dependent properties of these tissues through dynamic mechanical analysis (DMA) in tension and compression. General information on thermal degradations through differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) is also missing. Therefore, part of this work intends to fill this lack of the literature giving some insights into the cartilage internal composition and architecture, as well as the specificity of the activated mechanisms under constant stress or strain. Furthermore, numerical simulations were performed based on a hyper-viscoelastic mathematical formulation using a home-made open-source finite element (FE) solver (V-Biomech) in order to find a set of basic constitutive parameters that allow to replicate the experimental creep and relaxation behaviours of nasoseptal cartilage specimens from distinct regions of the quadrilateral cartilage (QLC). Thus, a complete standard biphasic poro-hyper-viscoelastic constitutive law was developed and validated. Finite Element Models (FEM) are gaining relevance to analyse soft biological components. As example, numerical simulations of the viscoelastic behaviours of the specimens harvested from anterior part of the QLC were performed to understand which of the constitutive parameters were more sensitive to achieve the best numerical-experimental agreement. The tools to reproduce these simulations in a more complex geometry (the whole nasal structure, with bony and cartilaginous components) were also developed and presented. The work still goes on it. |
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| Autores principais: | Fertuzinhos, Aureliano da Costa |
| Assunto: | Rhinoplasty Nasal cartilages Dynamic / thermal mechanical analysis Viscoelasticity Creep and relaxation Finite element method Rinoplastia Cartilagens nasais Análise mecânica dinâmica/térmica Viscoelasticidade Fluência e relaxação Método dos elementos finitos |
| Ano: | 2017 |
| País: | Portugal |
| Tipo de documento: | dissertação de mestrado |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade do Minho |
| Idioma: | inglês |
| Origem: | RepositóriUM - Universidade do Minho |
| Resumo: | The facial plastic surgery, and particularly the area of rhinoplasty, is undoubtedly a growing up market. Surgical techniques have been evolving to respond to very specific patient desires not only for functional reasons, but also to resolve aesthetic issues. Actually, it is moving plenty of money around the world, being a great scientific and commercial opportunity among researchers. The human nose is composed of three major portions separated by two well-defined regions of transition (K-area and S-area) that are very complicated to deal with in postoperative periods. The viscoelastic behaviour of soft biological tissues, especially that of nasal cartilages and adjacent subcutaneous/fatty tissues, is barely known. There are no studies on the viscoelastic characterization of the mechanical properties of nasal septum (NS), upper lateral cartilages (ULC), and lower lateral cartilages (LLC) in creep and relaxation (basic viscoelasticity features) neither on the determination of frequency- and temperature-dependent properties of these tissues through dynamic mechanical analysis (DMA) in tension and compression. General information on thermal degradations through differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) is also missing. Therefore, part of this work intends to fill this lack of the literature giving some insights into the cartilage internal composition and architecture, as well as the specificity of the activated mechanisms under constant stress or strain. Furthermore, numerical simulations were performed based on a hyper-viscoelastic mathematical formulation using a home-made open-source finite element (FE) solver (V-Biomech) in order to find a set of basic constitutive parameters that allow to replicate the experimental creep and relaxation behaviours of nasoseptal cartilage specimens from distinct regions of the quadrilateral cartilage (QLC). Thus, a complete standard biphasic poro-hyper-viscoelastic constitutive law was developed and validated. Finite Element Models (FEM) are gaining relevance to analyse soft biological components. As example, numerical simulations of the viscoelastic behaviours of the specimens harvested from anterior part of the QLC were performed to understand which of the constitutive parameters were more sensitive to achieve the best numerical-experimental agreement. The tools to reproduce these simulations in a more complex geometry (the whole nasal structure, with bony and cartilaginous components) were also developed and presented. The work still goes on it. |
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