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Elastic modulus

About: Elastic modulus is a research topic. Over the lifetime, 33153 publications have been published within this topic receiving 810247 citations.


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TL;DR: The proposed new type of inverse problem by which the spatial distribution of the relative elastic modulus of the tissue can be estimated only from the deformation or strain measurement seems promising for the quantitative differential diagnosis on the lesion in the tissue in vivo.
Abstract: In order to obtain noninvasively quantitative static mechanical properties of living tissue, the authors propose a new type of inverse problem by which the spatial distribution of the relative elastic modulus of the tissue can be estimated only from the deformation or strain measurement. The living tissue is modeled as a linear isotropic incompressible elastic medium which has the spatial distribution of the shear modulus, and the deformation or strain is supposedly measured ultrasonically. Assuming that there is no mechanical source in the region of interest, the authors derive a set of linear equations in which unknowns are the spatial derivatives of the relative shear modulus, and the coefficients are the strain and its spatial derivatives. By solving these equations, the spatial derivatives of the relative shear modulus are determined throughout the region, from which the spatial distribution of the relative shear modulus is obtained by spatial integration. The feasibility of this method was demonstrated using the simulated deformation data of the simple inclusion problem. The proposed method seems promising for the quantitative differential diagnosis on the lesion in the tissue in vivo. >

184 citations

Journal ArticleDOI
TL;DR: In this paper, the authors examined the tack of polymer melts on rigid substrates under conditions of short contact times and low pressures and showed that for relatively high pressures the tack is predicted to scale with 1/E so that for short contact time, t c, the tack was predicted to Scale with (t c /τ e ) 1/2, where τ e is the entanglement time.
Abstract: The tack of polymer melts on rigid substrates under conditions of short contact times and low pressures is examined. The substrate is modeled as a random rough surface with a distribution of asperities heights. The true contact area between the adhesive and the substrate is calculated for a given total load and elastic modulus of the substrate. The dependence of tack on contact time is accounted for by introducing the relaxation of the adhesive through a time-dependent elastic modulus. For relatively high pressures the tack is predicted to scale with 1/E so that for short contact times, t c , the tack is predicted to scale with (t c /τ e ) 1/2 , where τ e is the entanglement time. For lower pressures this simple scaling low is no longer valid and we predict a complex variation of tack with contact time and molecular parameters.

184 citations

Journal ArticleDOI
TL;DR: A series of Steered Molecular Dynamics simulations in explicit solvent is used to elucidate the influence of the pulling rate on the Young's modulus of individual tropocollagen molecules, and enables for the first time to predict the elastic properties of a single tropocollsagen molecule at physiologically and experimentally relevant pulling rates, directly from atomistic-level calculations.
Abstract: Collagen is an important structural protein in vertebrates and is responsible for the integrity of many tissues like bone, teeth, cartilage and tendon. The mechanical properties of these tissues are primarily determined by their hierarchical arrangement and the role of the collagen matrix in their structures. Here we report a series of Steered Molecular Dynamics (SMD) simulations in explicit solvent, used to elucidate the influence of the pulling rate on the Young's modulus of individual tropocollagen molecules. We stretch a collagen peptide model sequence [(Gly-Pro-Hyp)(10)](3) with pulling rates ranging from 0.01 to 100 m/s, reaching much smaller deformation rates than reported in earlier SMD studies. Our results clearly demonstrate a strong influence of the loading velocity on the observed mechanical properties. Most notably, we find that Young's modulus converges to a constant value of approximately 4 GPa tangent modulus at 8% tensile strain when the initially crimped molecule is straightened out, for pulling rates below 0.5 m/s. This enables us for the first time to predict the elastic properties of a single tropocollagen molecule at physiologically and experimentally relevant pulling rates, directly from atomistic-level calculations. At deformation rates larger than 0.5 m/s, Young's modulus increases continuously and approaches values in excess of 15 GPa for deformation rates larger than 100 m/s. The analyses of the molecular deformation mechanisms show that the tropocollagen molecule unfolds in distinctly different ways, depending on the loading rate, which explains the observation of different values of Young's modulus at different loading rates. For low pulling rates, the triple helix first uncoils completely at 10%-20% strain, then undergoes some recoiling in the opposite direction, and finally straightens for strains larger than 30%. At intermediate rates, the molecule uncoils linearly with increasing strain up to 35% strain. Finally, at higher velocities the triple helix does not uncoil during stretching.

184 citations

Journal ArticleDOI
TL;DR: In this article, the authors focused on the graded change requirements of bio-porous scaffolds in terms of physical and mechanical properties, and proposed three patterns (density, heterostructure and cell-size gradients) with Gyroid and Diamond unit cells, and fabricated by Selective Laser Melting (SLM) using Ti-6Al-4V.

183 citations

Journal ArticleDOI
TL;DR: It is demonstrated that high-friction properties similar to rubberlike materials can be obtained using microfiber arrays constructed from a stiff thermoplastic (polypropylene, 1 GPa) using polypropylene's higher interfacial shear strength.
Abstract: High dry friction requires intimate contact between two surfaces and is generally obtained using soft materials with an elastic modulus less than 10 MPa. We demonstrate that high-friction properties similar to rubberlike materials can also be obtained using microfiber arrays constructed from a stiff thermoplastic (polypropylene, 1 GPa). The fiber arrays have a smaller true area of contact than a rubberlike material, but polypropylene’s higher interfacial shear strength provides an effective friction coefficient of greater than 5 at normal loads of 8 kPa. At the pressures tested, the fiber arrays showed more than an order of magnitude increase in shear resistance compared to the bulk material. Unlike softer materials, vertical fiber arrays of stiff polymer demonstrate no measurable adhesion on smooth surfaces due to high tensile stiffness.

183 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023611
20221,303
20211,450
20201,401
20191,447
20181,369