title: Multiscale approach including microfibril scale to assess elastic constants of cortical bone based on neural network computation and homogenization method.
abstract: The complexity and heterogeneity of bone tissue require a multiscale modeling to understand its mechanical behavior and its remodeling mechanisms. In this paper, a novel multiscale hierarchical approach including microfibril scale based on hybrid neural network (NN) computation and homogenization equations was developed to link nanoscopic and macroscopic scales to estimate the elastic properties of human cortical bone. The multiscale model is divided into three main phases: (i) in step 0, the elastic constants of collagen-water and mineral-water composites are calculated by averaging the upper and lower Hill bounds; (ii) in step 1, the elastic properties of the collagen microfibril are computed using a trained NN simulation. Finite element calculation is performed at nanoscopic levels to provide a database to train an in-house NN program; and (iii) in steps 2-10 from fibril to continuum cortical bone tissue, homogenization equations are used to perform the computation at the higher scales. The NN outputs (elastic properties of the microfibril) are used as inputs for the homogenization computation to determine the properties of mineralized collagen fibril. The mechanical and geometrical properties of bone constituents (mineral, collagen, and cross-links) as well as the porosity were taken in consideration. This paper aims to predict analytically the effective elastic constants of cortical bone by modeling its elastic response at these different scales, ranging from the nanostructural to mesostructural levels. Our findings of the lowest scale's output were well integrated with the other higher levels and serve as inputs for the next higher scale modeling. Good agreement was obtained between our predicted results and literature data.
authors.affiliation: Université de Savoie, Laboratoire SYMME, BP 80439, Annecy-le-Vieux Cedex F74944, France.
authors.forename: Abdelwahed
authors.initials: A
authors.lastname: Barkaoui
authors.forename: Abdessalem
authors.initials: A
authors.lastname: Chamekh
authors.forename: Tarek
authors.initials: T
authors.lastname: Merzouki
authors.forename: Ridha
authors.initials: R
authors.lastname: Hambli
authors.forename: Ali
authors.initials: A
authors.lastname: Mkaddem
mesh_terms: D000465:Algorithms; D001842:Bone and Bones / Q000502:physiology*; D003094:Collagen; D003198:Computer Simulation; D055119:Elastic Modulus; D020342:Finite Element Analysis; D006801:Humans; D008954:Models, Biological; D016571:Neural Networks, Computer
chemical_list: D003094:Collagen
keywords: cortical bone; finite element method; homogenization method; multiscale approach; neural network computation