161. simulink-based multiscale model of the viscoelastic properties of skin

Department: Mechanical & Aerospace Engineering
Faculty Advisor(s): Marc A. Meyers

Primary Student
Name: Andrei Pissarenko
Email: apissare@ucsd.edu
Phone: 858-291-2579
Grad Year: 2019

Abstract
Skin is the outermost layer of the body of mammals. It acts as a protective barrier against external agents such as heat, light, infection, and injury. It must be able to withstand tremendous deformations and mitigate propagations of tears that can occur during growth, movement, or injuries. Skin is a non-linear, anisotropic, viscoelastic material that has the remarkable ability to adapt to the mechanics of its environment. Thus, understanding and characterizing its mechanical behavior can be crucial in contexts ranging from surgery, forensics, biomimicry, to engineering of protective gear, for example. It is believed that the dermis, skin?s median and thickest layer, mostly accounts for the mechanical tensile response. It is majorly composed of variably oriented layers of wavy collagen fibers (~60% of the dermis? volume), partially jointed by transverse elastin fibers (~4%), embedded in a viscous matrix called the ground substance. Our research proposes some new insight into the multiscale aspects of skin?s viscoelasticity through a top to bottom physical modelling approach, based on a deformation model of S-shaped collagen fibers, recently developed by our group. A modified Generalized Maxwell model is used to match experimental data from a set of tensile tests that we conducted on porcine skin. The obtained parameters define the macroscale behaviour of the dermis. SEM and TEM are used to describe the geometry of collagen fibers. In order to quantify processes such as shearing and sliding within the material, the model is later refined via a finite element model of wavy fibers in a viscous matrix. These models give us a clearer picture of the deformation mechanisms occurring in skin, highlighting its remarkable stretchability and tear resistance, while also complementing the database of skin?s mechanical properties.

Industry Application Area(s)
Life Sciences/Medical Devices & Instruments | Materials

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