Search results for "Elasticity"
showing 10 items of 736 documents
A Non-Local Two Dimensional Foundation Model
2012
Classical foundation models such as the Pasternak and the Reissner models have been recently reformulated within the framework of non-local mechanics, by using the gradient theory of elasticity. To contribute to the research effort in this field, this paper presents a two-dimensional foundation model built by using a mechanically based non-local elasticity theory, recently proposed by the authors. The foundation is thought of as an ensemble of soil column elements resting on an elastic base. It is assumed that each column element is acted upon by a local Winkler-like reaction force exerted by the elastic base, by contact shear forces and volume forces due, respectively, to adjacent and non-…
Complex Potential Function in Elasticity Theory: shear and torsion solution through line integrals
2012
Aim of this paper is to introduce a basis formulation framed into complex analysis valid to solve shear and torsion problems. Solution, in terms of a complex function related to the complete tangential stress field, may be evaluated performing line integrals only. This basis formulation framed into elasticity problems may be a useful support for a boundary method to verify the accuracy of an approximation of function solution. The numerical applications stress the latter point and show the validity of these formulas since exact solutions may be reached for sections where the exact solution is known.
Solution strategies for 1D elastic continuum with long-range interactions: Smooth and fractional decay
2010
Abstract An elastic continuum model with long-range forces is addressed in this study within the context of approximate analytical methods. Such a model stems from a mechanically-based approach to non-local theory where long-range central forces are introduced between non-adjacent volume elements. Specifically, long-range forces depend on the relative displacement, on the volume product between interacting elements and they are proportional to a proper, material-dependent, distance-decaying function. Smooth-decay functions lead to integro-differential governing equations whereas hypersingular, fractional-decay functions lead to a fractional differential governing equation of Marchaud type. …
Bending stress fields in composite laminate beams by a boundary integral formulation
1999
Abstract The elasticity of a composite laminate under bending loads is approached through a boundary integral formulation and solved by the boundary element method. The integral equations governing the behaviour of each layer within the laminate, are deduced using the reciprocity theorem. Exact analytical singular solutions of the generalized orthotropic elasticity, i.e. the fundamental solutions of the problem, are employed as the kernels of the integral equation. The formulation does not make any assumption as to the nature of the elastic response and it allows consideration of general section geometries and stacking sequences. The solution is obtained through the enforcement of the inter…
Impact of hydrothermal ageing on the thermal stability, morphology and viscoelastic performance of PLA/sisal biocomposites
2016
The influence of the combined exposure to water and temperature on the behaviour of polylactide/sisal biocomposites coupled with maleic acid anhydride was assessed through accelerated hydrothermal ageing. The biocomposites were immersed in water at temperatures from 65 to 85 °C, between the glass transition and cold crystallisation of the PLA matrix. The results showed that the most influent factor for water absorption was the percentage of fibres, followed by the presence of coupling agent, whereas the effect of the temperature was not significant. Deep assessment was devoted to biocomposites subjected to hydrothermal ageing at 85 °C, since it represents the extreme degrading condition. Th…
An integral framework for computational thermo-elastic homogenization of polycrystalline materials
2023
A grain scale framework for thermo-elastic analysis and computational homogenization of polycrystalline materials is proposed. The morphology of crystal aggregates is represented employing Voronoi tessellations, which retain the main statistical features of polycrystalline materials. The behaviour of the individual grains is modelled starting from an integral representation for anisotropic thermo-elasticity, which is numerically addressed through a dual reciprocity boundary element method. The integrity of the aggregate is enforced through suitable intergranular thermo-elastic continuity conditions. By virtue of the features of the underlying formulation, the polycrystalline thermo-elastic …
Ecohydrological modelling of flow duration curve in Mediterranean river basins
2013
Abstract Flow duration curve provides an important synthesis of the relevant hydrological processes occurring at the basin scale, and, although it is typically obtained from field observations, different theoretical approaches finalized to its indirect reconstruction have been developed in recent years. In this study a recent ecohydrological model for the probabilistic characterization of base flows is tested through its application to a study catchment located in southern Italy, where long historical series of daily streamflow are available. The model, coupling soil moisture balance with a simplified scheme of the hydrological response of the basin, provides the daily flow duration curve. …
The superlattice model of lateral organization of membranes and its implications on membrane lipid homeostasis.
2008
AbstractMost biological membranes are extremely complex structures consisting of hundreds of different lipid and protein molecules. According to the famous fluid-mosaic model lipids and many proteins are free to diffuse very rapidly in the plane of the membrane. While such fast diffusion implies that different membrane lipids would be laterally randomly distributed, accumulating evidence indicates that in model and natural membranes the lipid components tend to adopt regular (superlattice-like) distributions. The superlattice model, put forward based on such evidence, is intriguing because it predicts that 1) there is a limited number of allowed compositions representing local minima in mem…
Role of Membrane Lipids for the Activity of Pore Forming Peptides and Proteins
2010
Bilayer lipids, far from being passive elements, have multiple roles in polypeptide-dependent pore formation. Lipids participate at all stages of the formation of pores by providing the binding site for proteins and peptides, conditioning their active structure and modulating the molecular reorganization of the membrane complex. Such general functions of lipids superimpose to other particular roles, from electrostatic and curvature effects to more specific actions in cases like cholesterol, sphingolipids or cardiolipin.
Time Use and Food Taxation in Spain
2009
We evaluate the welfare impact of changing the VAT on food in a context in which households can produce home meals for own consumption that compete with meals served in restaurants. Home production of meals requires the combination of food and time inputs. The fiscal treatment in home production of both the inputs and the final product differs from market production of meals, generating different channels of inefficiency. We calibrate a simple general-equilibrium model for the Spanish economy that identifies three types of consumers according to their income, and simulate the effects of some experiments related to how food is taxed. The results suggest that if we focus only on aggregate wel…