Scheider I, Xiao T, Yilmaz E, Schneider G A, Huber N, Bargmann S
Institute of Materials Research, Materials Mechanics/ACE-Centre, Helmholtz-Zentrum Geesthacht, Germany.
Institute of Advanced Ceramics, Hamburg University of Technology, Germany.
Acta Biomater. 2015 Mar;15:244-53. doi: 10.1016/j.actbio.2014.11.036. Epub 2014 Dec 5.
Dental enamel is a highly anisotropic and heterogeneous material, which exhibits an optimal reliability with respect to the various loads occurring over years. In this work, enamel's microstructure of parallel aligned rods of mineral fibers is modeled and mechanical properties are evaluated in terms of strength and toughness with the help of a multiscale modeling method. The established model is validated by comparing it with the stress-strain curves identified by microcantilever beam experiments extracted from these rods. Moreover, in order to gain further insight in the damage-tolerant behavior of enamel, the size of crystallites below which the structure becomes insensitive to flaws is studied by a microstructural finite element model. The assumption regarding the fiber strength is verified by a numerical study leading to accordance of fiber size and flaw tolerance size, and the debonding strength is estimated by optimizing the failure behavior of the microstructure on the hierarchical level above the individual fibers. Based on these well-grounded properties, the material behavior is predicted well by homogenization of a representative unit cell including damage, taking imperfections (like microcracks in the present case) into account.
牙釉质是一种高度各向异性且非均质的材料，对于多年来出现的各种载荷，它展现出了最佳的可靠性。在这项工作中，利用多尺度建模方法对矿化纤维平行排列的牙釉质微观结构进行建模，并从强度和韧性方面评估其力学性能。通过将建立的模型与从这些矿化纤维中提取的微悬臂梁实验确定的应力 - 应变曲线进行比较来验证该模型。此外，为了进一步深入了解牙釉质的损伤容限行为，通过微观结构有限元模型研究了微晶尺寸，当微晶尺寸低于该尺寸时，结构对缺陷变得不敏感。关于纤维强度的假设通过数值研究得到验证，该研究得出纤维尺寸与缺陷容限尺寸的一致性，并通过优化单个纤维之上层次结构的微观结构失效行为来估计脱粘强度。基于这些有充分依据的性能，通过考虑缺陷（如本例中的微裂纹）的代表性单胞的均匀化，能够很好地预测材料行为。
