Nano finite element modeling of the mechanical behavior of biocomposites using multi-scale (virtual internal bond) material models

It is evident that biocomposites, specifically mineralized Type-I collagen fibrils, have strong mechanical properties, such as a desirable combination of elastic modulus, fracture toughness, and fracture strength. The mineral Hydroxyapatite [Hap] by itself is stiffer, and it is not clear whether a collagen fiber by itself has a lower breaking strength than the mineralized fiber. Hence, the objective of this paper is to develop, outline, apply, and demonstrate issues involving a new nano explicit finite element based framework, by which the mechanical behavior of mineralized collagen fibrils and their constituents can be studied. A multi-scale virtual internal bond model is used to model the material behavior and failure of such biocomposites. In this research two models have been studied. The first model attempts to illustrate the hypothesis that materials are less sensitive to flaws at nanoscale and the second model studies the mechanical behavior of a nano sized dahlite mineral crystal commonly found in collagen fibril. Two important implementation characteristics have been introduced and illustrated, namely that scaled properties can be used at the micro and nano length scales along with scaled dimensions and secondly the loading time can be appropriately scaled without the loading becoming a dynamic loading. (c) 2007 Wiley Periodicals, Inc.