title: Protein viscosity, mineral fraction and staggered architecture cooperatively enable the fastest stress wave decay in load-bearing biological materials.
abstract: One of the key functions of load-bearing biological materials, such as bone, dentin and sea shell, is to protect their inside fragile organs by effectively damping dynamic impact. How those materials achieve this remarkable function remains largely unknown. Using systematic finite element analyses, we study the stress wave propagation and attenuation in cortical bone at the nanoscale as a model material to examine the effects of protein viscosity, mineral fraction and staggered architecture on the elastic wave decay. It is found that the staggered arrangement, protein viscosity and mineral fraction work cooperatively to effectively attenuate the stress wave. For a typical mineral volume fraction and protein viscosity, an optimal staggered nanostructure with specific feature sizes and layouts is able to give rise to the fastest stress wave decay, and the optimal aspect ratio and thickness of mineral platelets are in excellent agreement with experimental measurements. In contrary, as the mineral volume fraction or the protein viscosity goes much higher, the structural arrangement is seen having trivial effect on the stress wave decay, suggesting that the damping properties of the composites go into the structure-insensitive regime from the structure-sensitive regime. These findings not only significantly add to our understanding of the structure-function relationship of load-bearing biological materials, and but also provide useful guidelines for the design of bio-inspired materials with superior resistance to impact loading.
authors.affiliation: School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore 639798, Singapore; Institute of High Performance Computing, A⁎STAR, Singapore 138632, Singapore.
authors.forename: Mahan
authors.initials: M
authors.lastname: Qwamizadeh
authors.affiliation: School of Civil Engineering, Wuhan University, Wuhan, Hubei 430072, China. Electronic address: zhang_zuoqi@whu.edu.cn.
authors.forename: Zuoqi
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore 639798, Singapore. Electronic address: kzhou@ntu.edu.sg.
authors.forename: Kun
authors.initials: K
authors.lastname: Zhou
authors.affiliation: Institute of High Performance Computing, A⁎STAR, Singapore 138632, Singapore.
authors.forename: Yong Wei
authors.initials: YW
authors.lastname: Zhang
mesh_terms: D015519:Bone Density; D000071538:Cortical Bone / Q000502:physiology*; D020342:Finite Element Analysis; D008954:Models, Biological; D011506:Proteins / Q000737:chemistry*; D013314:Stress, Mechanical; D014783:Viscosity; D016474:Weight-Bearing
chemical_list: D011506:Proteins
keywords: Damping effects; Dynamic loading; Mineralized tissue; Optimal aspect ratio; Staggered structure