Relaxed incremental variational approach for the modeling of damage-induced stress hysteresis in arterial walls.
In this paper, a three-dimensional relaxed incremental variational damage model is proposed, which enables the description of complex softening hysteresis as observed in supra-physiologically loaded arterial tissues, and which thereby avoids a loss of convexity of the underlying formulation. The proposed model extends the relaxed formulation of Balzani and Ortiz [2012. Relaxed incremental variational formulation for damage at large strains with application to fiber-reinforced materials and materials with truss-like microstructures. Int. J. Numer. Methods Eng. 92, 551-570], such that the typical stress-hysteresis observed in arterial tissues under cyclic loading can be described. This is mainly achieved by constructing a modified one-dimensional model accounting for cyclic loading in the individual fiber direction and numerically homogenizing the response taking into account a fiber orientation distribution function. A new solution strategy for the identification of the convexified stress potential is proposed based on an evolutionary algorithm which leads to an improved robustness compared to solely Newton-based optimization schemes. In order to enable an efficient adjustment of the new model to experimentally observed softening hysteresis, an adjustment scheme using a surrogate model is proposed. Therewith, the relaxed formulation is adjusted to experimental data in the supra-physiological domain of the media and adventitia of a human carotid artery. The performance of the model is then demonstrated in a finite element example of an overstretched artery. Although here three-dimensional thick-walled atherosclerotic arteries are considered, it is emphasized that the formulation can also directly be applied to thin-walled simulations of arteries using shell elements or other fiber-reinforced biomembranes.
Institut für Mechanik, Fakultät für Ingenieurwissenschaften/Abteilung Bauwissenschaften, Universität Duisburg-Essen, Universitätsstr. 15, 45141 Essen, Germany. Electronic address: t.schmidt@uni-due.de.
Thomas
T
Schmidt
Institut für Mechanik und Flächentragwerke, Fakultät Bauingenieurwesen, and Dresden Center for Computational Materials Science, Technische Universität Dresden, 01062 Dresden, Germany. Electronic address: daniel.balzani@tu-dresden.de.
Daniel
D
Balzani
D000465:Algorithms; D001011:Aorta / Q000473:pathology*; D002339:Carotid Arteries / Q000473:pathology*; D020342:Finite Element Analysis; D006801:Humans; D008955:Models, Cardiovascular; D013314:Stress, Mechanical
Atherosclerotic arteries; Convexity; Mesh-independency; Orientation distribution; Soft biological tissues; Softening