Search results for "LINEAR ELASTICITY"
showing 10 items of 41 documents
Concrete softening effects on the axial capacity of RC jacketed circular columns
2016
Abstract Among the different strengthening techniques to repair RC structures, reinforced concrete (RC) jacketing is one of the most commonly adopted, especially for columns. Its wide application is due to its easy application and relatively reduced cost with respect to other methods (e.g. FRP wrapping, Shape Memory Alloy active confinement). The target of RC jacketing is to increase axial, flexural capacity and ductility of weak existing members by means of two main effects: confinement action provided by the jacket and composite action between external jacket and inner concrete. Different theoretical studies have been carried out to calculate the strength enhancement due to confinement ac…
Mechanical behaviour of Palermo and Marsala calcarenites (Sicily), Italy
2016
Abstract This paper aims at finding a framework for the Sicilian Calcarenites relating the strength and the deformability of these materials to their geological and structural features: fabric, bonding, initial and actual specific volume. In particular, this study sets out to separate the effects of fabric and of bonding on the mechanical response. The investigated lithotypes, Calcarenites from Palermo and Marsala, outcropping in many areas of southwestern Sicily, are characterized by sudden changes in their deformability, strength and permeability characteristics. The geotechnical identification, by means of computerized axial tomography and thin section petrographic analysis suggested a s…
Restraining approach for the spurious kinematic modes in hybrid equilibrium element
2013
The present paper proposes a rigorous approach for the elimination of spurious kinematic modes in hybrid equilibrium elements, for three well known mesh patches. The approach is based on the identification of the dependent equations in the set of inter-element and boundary equilibrium equations of the sides involved in the spurious kinematic mode. Then the kinematic variables related to the dependent equations are reciprocally constrained and, by application of master slave elimination method, the set of inter-element equilibrium equations is reduced to full rank. The elastic solutions produced by means of the proposed approach verify the homogeneous, the inter-element and the boundary equi…
A symmetric Galerkin boundary/domain element method for finite elastic deformations
2000
Abstract The Symmetric Galerkin Boundary Element Method (SGBEM) is reformulated for problems of finite elasticity with hyperelastic material and incompressibility, using fundamental solutions related to a (fictitious) homogeneous isotropic and compressible linear elastic material. The proposed formulation contains, besides the standard boundary integrals, domain integrals which account for the problem's nonlinearities through some (fictitious) initial strain and stress fields required to satisfy appropriate “consistency” equations. The boundary/domain integral equation problem so obtained is shown to admit a stationarity principle (a consequence of the Hu-Washizu one), which covers a number…
Spectral analysis of the Neumann-Poincaré operator and characterization of the stress concentration in anti-plane elasticity
2012
When holes or hard elastic inclusions are closely located, stress which is the gradient of the solution to the anti-plane elasticity equation can be arbitrarily large as the distance between two inclusions tends to zero. It is important to precisely characterize the blow-up of the gradient of such an equation. In this paper we show that the blow-up of the gradient can be characterized by a singular function defined by the single layer potential of an eigenfunction corresponding to the eigenvalue 1/2 of a Neumann–Poincare type operator defined on the boundaries of the inclusions. By comparing the singular function with the one corresponding to two disks osculating to the inclusions, we quant…
Mechanical properties of sol–gel derived SiO2 nanotubes
2014
The mechanical properties of thick-walled SiO2 nanotubes (NTs) prepared by a sol–gel method while using Ag nanowires (NWs) as templates were measured by using different methods. In situ scanning electron microscopy (SEM) cantilever beam bending tests were carried out by using a nanomanipulator equipped with a force sensor in order to investigate plasticity and flexural response of NTs. Nanoindentation and three point bending tests of NTs were performed by atomic force microscopy (AFM) under ambient conditions. Half-suspended and three-point bending tests were processed in the framework of linear elasticity theory. Finite element method simulations were used to extract Young’s modulus values…
Finite element analysis of the out-of-plane behavior of FRP strengthened masonry panels
2017
Abstract In the present study a numerical model is proposed for the response of out-of-plane loaded calcarenite masonry walls strengthened with vertical CFRP strips applied on the substrate by means of epoxy resin. A simplified structural scheme is considered consisting in a beam fixed at one end, subjected to constant axial load and out-of-plane lateral force monotonically increasing. Two different constraint conditions are taken into account: in the first one, the panel is assumed free to rotate at the top end while, in the second one, the rotation is restrained. Three-dimensional finite elements are used for the calcarenite parts and an equivalent constitutive law available in the litera…
On the strong closure of strains and stresses in linear elasticity
1999
We consider the following special problem related to the optimal layout problems of materials: given two linear elastic materials, the elasticity tensors of which are C1 and C2, and a force f, find the strong closure of strains and stresses as the distribution of the materials varies, or, alternatively, find the sets of elasticity tensors which generate these strong closures. In this paper, it is shown that the local incompatibility conditions depending on C1, C2 and the local properties of strains or stresses completely characterize these sets. A connection to multiple-well problems is established.
Modelling intergranular and transgranular micro-cracking in polycrystalline materials
2018
Abstract In this work, a grain boundary formulation for intergranular and transgranular micro-cracking in three-dimensional polycrystalline aggregates is presented. The formulation is based on the displacement and stress boundary integral equations of solid mechanics and it has the advantage of expressing the polycrystalline problem in terms of grain boundary variables only. The individual grains within the polycrystalline morphology are modelled as generally anisotropic linear elastic domains with random spatial orientation. Transgranular micro-cracking is assumed to occur along specific cleavage planes, whose orientation in space within the grains depend upon the crystallographic lattice.…
Analysis of stress concentration during tension of round pultruded composite rods
2008
The stress state in a solid round transversely isotropic rod loaded with balanced shear stresses on a part of its lateral surface is considered. The change in gripping conditions is simulated by varying the distribution of statically equivalent shear stresses. The solution for the stress state was obtained using exact equations of linear theory of elasticity of anisotropic body. An analysis of the distribution of longitudinal and hoop stresses showed that at the grip edges a very high stress concentration is possible, which depends on the radius of the tensioned rod and the distribution of shear stresses on the gripped surface. At the grip edges, the longitudinal and hoop stresses tend to i…