Hydrostatic stress

About: Hydrostatic stress is a research topic. Over the lifetime, 1568 publications have been published within this topic receiving 37773 citations.

Development, validation and analysis of an efficient micro-scale representative volume element for unidirectional composites

Abstract: In the present work, a simple procedure to build periodic representative volume elements (RVE) is developed for UD composite laminae. The procedure is based on the alteration of an initially regular fibre distribution, and includes the possibility to start from different fibre configurations, to use of non-uniform fibre diameter, and for fibres to cross the RVE edges. The obtained RVEs were found to differ from a theoretical hard-core process in terms of Voronoi equivalent radius distribution and nearest neighbour distribution, for which a novel analytical method is proposed. The fibre distributions were instead in good agreement with real microstructures in terms of both short- and long-range morphological indexes, especially when the actual fibre diameter distribution is used. A novel short-range index, called neighbour distance diagram, is also proposed to represent the distances of all the fibre neighbours. The RVEs were then compared to real microstructures in terms of stress distributions. The Cumulative Distribution Function (CDF) of Local Maximum Principal Stress (LMPS) and the Local Hydrostatic Stress (LHS) in the matrix are calculated under transverse, shear and longitudinal stresses and under a temperature gradient, validating the RVE also under a mechanical point of view. Using uniform fibre diameter was found not to have a significant influence on the stress distributions. Eventually, a parametric analysis was carried out to analyse the influence of the fibre volume fraction on LMPS and LHS CDF, under both mechanical and thermal loading conditions.

Strain distribution in arbitrarily shaped quantum dots with nonuniform composition

Abstract: Extensive research over the past several years has revealed graded composition and strong atomistic intermixing between a quantum dot (QD) and its surrounding material. In this paper, the strain and stress fields induced by a QD with an initial misfit strain due to its nonuniform composition are investigated. A general expression of the stress field for an arbitrarily shaped QD structure with a nonuniform composition is presented. It is found that the hydrostatic stress and strain are proportional to the initial misfit strain inside the QD but vanish outside it. The stress field in an arbitrarily shaped QD with a linearly graded composition is studied in detail, and a simple formula containing integrals over the boundary of the QD is derived. It can greatly simplify the numerical calculation of the elastic fields. Based on this formula, a closed-form analytical solution for a cuboidal QD with a linearly graded composition is obtained. It is also demonstrated that the strains inside and around the QD are s...

Bone toughening through stress-induced non-collagenous protein denaturation

Abstract: Bone toughness emerges from the interaction of several multiscale toughening mechanisms. Recently, the formation of nanoscale dilatational bands and hence the accumulation of submicron diffuse damage were suggested as an important energy dissipation processes in bone. However, a detailed mechanistic understanding of the effect of this submicron toughening mechanism across multiple scales is lacking. Here, we propose a new three-dimensional ultrastructure volume element model showing the formation of nanoscale dilatational bands based on stress-induced non-collagenous protein denaturation and quantify the total energy released through this mechanism in the vicinity of a propagating crack. Under tensile deformation, large hydrostatic stress develops at the nanoscale as a result of local confinement. This tensile hydrostatic stress supports the denaturation of non-collagenous proteins at organic–inorganic interfaces, which leads to energy dissipation. Our model provides new fundamental understanding of the mechanism of dilatational bands formation and its contribution to bone toughness.