Search results for " strutture"
showing 10 items of 232 documents
An enhanced grain-boundary framework for computational homogenization and micro-cracking simulations of polycrystalline materials
2015
An enhanced three-dimensional (3D) framework for computational homogenization and intergranular cracking of polycrystalline materials is presented. The framework is aimed at reducing the computational cost of polycrystalline micro simulations, with an aim towards effective multiscale modelling. The scheme is based on a recently developed Voronoi cohesive-frictional grain-boundary formulation. A regularization scheme is used to avoid excessive mesh refinements often induced by the presence of small edges and surfaces in mathematically exact 3D Voronoi morphologies. For homogenization purposes, periodic boundary conditions are enforced on non-prismatic periodic micro representative volume ele…
A micro-mechanical model for grain-boundary cavitation in polycrystalline materials
2015
In this work, the grain-boundary cavitation in polycrystalline aggregates is investigated by means of a grain-scale model. Polycrystalline aggregates are generated using Voronoi tessellations, which have been extensively shown to retain the statistical features of real microstructures. Nucleation, thickening and sliding of cavities at grain boundaries are represented by specific cohesive laws embodying the damage parameters, whose time evolution equations are coupled to the mechanical model. The formulation is presented within the framework of a grain-boundary formulation, which only requires the discretization of the grain surfaces. Some numerical tests are presented to demonstrate the fea…
A three-dimensional grain boundary formulation for microstructural modeling of polycrystalline materials
2013
Abstract A three-dimensional grain boundary formulation is presented for the analysis of polycrystalline microstructures. The formulation is based on a boundary integral representation of the elastic problem for the single grains of the polycrystalline aggregate and it is expressed in terms of the intergranular fields, namely displacements and tractions, that play an important role in polycrystalline micromechanics. The artificial polycrystalline morphology is represented using the Hardcore Voronoi tessellation, which is simple to generate and able to embody the main statistical features of polycrystalline microstructures. The details of the microstructure generation and meshing, which invo…
Analytical solution for composite layered beam subjected to uniformly distributed load
2016
ABSTRACTThe article presents an analytical theory for multilayered composite beams subjected to transverse uniformly distributed loads. The formulation is based on a layerwise model characterized by third-order approximation of the axial displacements and fourth-order approximation of the transverse displacements. The layerwise kinematical model is rewritten in terms of generalized variables. The beam equilibrium equations, expressed in terms of stress resultant, allow writing the boundary value governing problem. The layerwise fields are obtained by postprocessing steps. The main advantage is to ensure the accuracy level associated to the layerwise formulations preserving the computational…
Boundary Element Method for Composite Laminates
2017
The boundary element method (BEM) is a numerical technique to solve engineering/physical problems formulated in terms of boundary integral equations. Composite laminates are assemblages of stacked different materials layers, generally consisting of variously oriented fibrous composite materials
Magneto-Electro-Elastic Bimorph Analysis by the Boundary Element Method
2008
The influence of the magnetic configuration on the behavior of magneto-electro-elastic bimorph beams is analyzed by using a boundary element approach. The problem is formulated by using the generalized displacements and generalized tractions. The boundary integral equation formulation is obtained by extending the reciprocity theorem to magneto-electro-elastic problems; it is numerically implemented by using the boundary element method multidomain technique to address problems involving nonhomogeneous configurations. Results under different magnetic configurations are compared highlighting the characteristic features of magnetopiezoelectric behavior particularly focusing on the link between …
Large deflection of magneto-electro-elastic laminated plates
2014
Abstract A model for the large deflection analysis of magneto-electro-elastic laminated plates is derived. The first order shear deformation theory and the von Karman stress function approach are employed. A set of resolving partial differential equations involving kinematical variables and the stress function is obtained as a consequence of the preliminary condensation of the electro-magnetic state to the plate kinematics. A closed form solution for simply-supported plates is presented. Numerical results are carried out for plates consisting of piezoelectric BaTiO 3 and piezomagnetic CoFe 2 O 4 layers. These results show the influence of large deflections on the plate response and could be…
Onthe repeatability of electromechanical impedance for monitoring of bonded joints
2015
The repeatability and sensitivity of the electromechanical impedance (EMI) method when employed for the structural health monitoring of bonded joints were investigated. A simple joint was assembled by bonding an aluminum strip to a square aluminum plate. Two rounds of experiments were performed. The first set aimed at verifying the repeatability of the method. The joint was monitored by using one piezoelectric sensor. The PZT was glued to the plate and never removed, whereas a poorly bonded joint was assembled and disassembled three times. For each case, the electromechanical signature was measured during the curing of the adhesive. After the three tests, the same joint was built with a dif…
Numerical analysis of a piezoelectric structural health monitoring system for composite flange-skin delamination detection
2013
Abstract In this paper, a piezoelectric based Structural Health Monitoring (SHM) system is proposed to detect skin/stiffener debonding and delamination cracks proper of laminated composite structures. The SHM system is analyzed by means of a boundary element code implemented in the framework of piezoelectricity. The multidomain technique, coupled with an interface spring model, is used to model laminated composite structures as well as the bonding between the host delaminated structure and the piezoelectric sensor. Static sensitivity analyses are firstly performed on a drop-ply delaminated structure in order to identify a suitable configuration for the sensor. Then, the dynamic electromecha…
Electroelastic Analysis of Piezoelectric Composite Laminates by Boundary Integral Equations
2004
A boundary integral representation for the electroelastic state in piezoelectric composite laminates subjected to axial extension, bending, torsion, shear/bending, and electric loadings is proposed. The governing equations are presented in terms of electromechanical generalized variables by the use of a suitable matrix notation. Thus, the three-dimensional electroelasticity solution for piezoelectric composite laminates is generated from a set of two partially coupled differential equations defined on the cross section of each individual ply within the laminate. These ply equations are linked through the interface conditions, which allow restoration of the model of the laminate as a whole. …