Computational Micromechanics of Biological Materials: Bone and Wood

Abstract

Despite complex hierarchical organization of bone and wood, it was recently possible to identify a few elementary components at the micro and nanolevel of these material classes for the explanation of the diversity of macroscopic (poro-)elastic properties of different bones and woods [2, 3]. The mechanical properties (i.e. elasticity) of these elementary components are (up to experimental scattering) the same across a variety of different bones and woods, respectively; they are ’universal’, i.e., independent of tissue-type, species, and anatomical location. The mechanical interaction between these elementary components (mechanical morphology) and the dosages of these components in different tissues determine the macroscopic material properties. Having in mind that, as regards bone, these dosages are dependent on complex biochemical control cycles (defining the metabolism of the organism), the purely mechanical theory can be linked to biology, biochemistry, and, on the applied side, to clinical practice. Drug-driven or genetically driven changes in metabolisms lead to changes in the dosages of elementary components. The effects of these metabolic changes on the mechanical behavior of skeletal (sub)systems under well-defined loading conditions (e.g., downfall of elderly persons with osteoporosis) can then be studied by feeding structural models (e.g., Finite Element models [4]) of whole bones with the aforementioned macroscopic material properties - the output of the micromechanical models. This is probably highly relevant for patient-specific non-invasive bone disease diagnosis and therapy. As regards wood, our nano-to-macro approach is expected to support optimization of technological processes, such as drying.