A. Dorogoy

TL;DR: In this article, a modified shear-compression specimen (SCS) for large strain testing over a wide range of strain rates is presented, which consists of creating two diametrically opposed semi-circular slots.

Abstract: In this study, a newly developed nanoscale modulus mapping is applied in order to visualize the 2D-distribution of mechanical characteristics in the aragonitic nacre layer of Perna canaliculus (green mussel) shells. Modulus maps provide lateral resolution of about 10 nm. They allow the aragonitic mineral (CaCO 3 ) tablets and the interfaces between them to be clearly resolved, which are filled by an organic substance (mainly beta-chitin). The experimental data are compared with finite element simulations that also take into account the tip radius of curvature and the thickness of organic layers, as measured by means of scanning electron microscopy with backscattered electrons. Based on this comparison, the Young modulus of beta-chitin is extracted. The obtained number, E β = 40 GPa, is higher than previously evaluated. The collected maps reveal that the elastic modules in the nacre layer change gradually across the ceramic/organic interfaces within a spatial range four times wider than the thickness of the organic layers. This is possibly due to inhomogeneous distribution of organic macromolecules within ceramic tablets. According to the data, the concentration of macromolecules gradually increases when approaching the organic/ceramic interfaces. A behavior of this type is unique to biogenic materials and distinguishes them from synthetic composite materials. Finally, three possible mechanisms that attempt to explain why gradual changes of elastic modules significantly enhance the overall resistance to fracture of the nacre layer are briefly discussed. The experimental findings support the idea that individual ceramic tablets, comprising the nacre, are built of the compositionally and functionally graded ceramic material. This sheds additional light on the origin ofthe superior mechanical properties of biogenic composites.

TL;DR: In this article, the effect of geometrical parameters, such as gage height and root radius, on the stress and strain distribution and concentration was investigated numerically using three-dimensional elastoplastic finite element simulations.

TL;DR: If the various physical, geometrical and mechanical parameters of the bone-implant system are well-defined, the insertion process can be simulated prior to the surgical act, and predict, tailor and contribute to maximize the success of dental implantation in a personalized manner.