A constitutive model for vascular tissue that integrates fibril, fiber andcontinuum levels
2010 (English)Report (Other academic)
A fundamental understanding of the mechanical properties of the extracellular matrix (ECM) is critically important to quantify the amount of macroscopic stress and/or strain transmitted to the cellular level of vascular tissue. Structural constitutive models integrate histological and mechanical information, and hence, allocate stress and strain to the different micro-structural components of the vascular wall. The present work proposes a novel multi-scale structural constitutive model for passive vascular tissue, where collagen fibers are assembled by proteoglycan (PG) cross-linked collagen fibrils and reinforce an otherwise isotropic matrix material. Multiplicative kinematics account for straightening and stretching of collagen fibrils and an orientation density function captures the spatial organization of collagen fibers in the tissue. Mechanical and structural assumptions at the collagen fibril level define a piece-wise analytical stress-stretch response of collagen fibers, which in turn is integrated over the unit sphere to constitute the tissue’s macroscopic mechanical properties. The proposed model displays salient macroscopic feature of vascular tissue, and employs material and structural parameters of clear physical meaning. Model parameters were estimated from meanpopulation data of the normal and aneurysmatic aortic wall and used to predict in-vivo stress states of patient-specific vascular geometries, thought to demonstrate the robustness of the particular Finite Element (FE) implementation. The collagen fibril level of the multi-scale constitutive formulation provides an interface to integrate vascular wall biology and to account for collagen turn-over for example.
Place, publisher, year, edition, pages
Stockholm: KTH , 2010.
Trita-HFL, ISSN 1104-6813 ; 497
IdentifiersURN: urn:nbn:se:kth:diva-29140OAI: oai:DiVA.org:kth-29140DiVA: diva2:392591
QC 2011012011-01-272011-01-272011-01-27Bibliographically approved