Search results for "MESHLESS"

A multi-sphere particle numerical model for non-invasive investigations of neuronal human brain activity

2013

In this paper, a multi-sphere particle method is built- up in order to estimate the solution of the Poisson's equation with Neumann boundary conditions describing the neuronal human brain activity. The partial difierential equations governing the relationships between neural current sources and the data produced by neuroimaging technique, are able to compute the scalp potential and magnetic fleld distributions generated by the neural activity. A numerical approach is proposed with current dipoles as current sources and going on in the computation by avoiding the mesh construction. The current dipoles are into an homogeneous spherical domain modeling the head and the computational approach i…

On the use of a meshless solver for PDEs governing electromagnetic transients

2009

In this paper some key elements of the Smoothed Particle Hydrodynamics methodology suitably reformulated for analyzing electromagnetic transients are investigated. The attention is focused on the interpolating smoothing kernel function which strongly influences the computational results. Some issues are provided by adopting the polynomial reproducing conditions. Validation tests involving Gaussian and cubic B-spline smoothing kernel functions in one and two dimensions are reported.

ON THE UNIT CELL BOUNDARY VALUE PROBLEM WITH MESHLESS FORMULATION FOR MASONRY STRUCTURES

2017

In a generic multi-scale computational homogenization (CH) procedure, the crucial point is the definition and the solution of the Unit Cell (UC) Boundary Value Problem (BVP). The main aspects to be chosen for the formulation of the UC BVP are: (i) geometry; (ii) bound- ary conditions (BCs); (iii) material models; (iv) numerical approximation techniques. All these components play a key-role in the efficiency of the multi-scale procedure. In the present study, the UC BVP is formulated for running bond masonry according to a dis- placement based variational formulation, where the material of the blocks is considered indefi- nitely elastic and the mortar joints are simulated by zero-thickness e…

Free vibrations of anisotropic panels

2004

A meshfree approach, called Displacement Boundary Method, for the analysis of in-plane and out-of-plane free vibrations of anisotropic plates is presented. The discretization process is based on the use of a modified variational principle and the static fundamental solutions of the problem operators. The stiffness and mass matrices are frequencyindependent, symmetric and positive definite and their computation requires boundary integrations of regular kernels only. Thus, the final resolving system can be solved with classical approaches by using standard numerical procedures. Numerical results are presented to show the accuracy and effectiveness of the method.

A FE-Meshless Multiscale Approach for Masonry Materials

2015

Abstract A FE-Meshless multiscale computational strategy for the analysis of running bond masonry is presented. The Meshless Method (MM) is adopted to solve the boundary value problem (BVP) at the mesoscopic level. The representative unit cell is composed by the aggregate and the surrounding joints, the former assumed to behave elastically while the latter are simulated as non-associated elastic-plastic zero-thickness interfaces with a softening response. Macroscopic localization of plastic bands is obtained performing a spectral analysis of the tangent stiffness matrix. Localized plastic bands are embedded into the quadrature points area of the macroscopic finite elements.

Multi-scale computational homogenization with applications to masonry structures

FE·Meshless multiscale modeling of heterogeneous periodic materials

2013

The computational mutiscale modeling of periodic heterogeneous materials, characterized by the assembly of units and joints, represents a compromise between the inaccuracy resulting from the macro modeling approach and the computational effort of the meso modeling. Assuming that the heterogeneities are orders of magnitude smaller than the structure dimensions, according to the multiscale approach, the macroscopic stresses and strains around a certain point can be found by averaging the stresses and the strains in a small representative part of the microstructure or a representative volume element (RVE) attributed to that point. A first-order two-scale scheme has been used to model heterogen…

Advancements on the FE·Meshless CH for the analysis of heterogeneous periodic materials

Over the last few years, the intrinsic role of different spatial scales in the mechanics of materials has been well recognized. Generally, two main different scales can be identified in the heterogeneous materials: the macroscopic level, which coincides with the global structural one, and the mesoscopic level, that is the scale at which the heterogeneities can be identified and where the most relevant nonlinear mechanical phenomena occur. In this framework, substantial progress has been made in the two-scale computational homogenization (CH). This method is essentially based on the on the fly assessment of the macroscopic constitutive behavior from the boundary value problem (BVP) of a stat…

CH of masonry materials via meshless meso-modeling

2014

In the present study a multi-scale computational strategy for the analysis of masonry structures is presented. The structural macroscopic behaviour is obtained making use of the Computational Homogenization (CH) technique based on the solution of the boundary value problem (BVP) of a detailed Unit Cell (UC) chosen at the meso-scale and representative of the heterogeneous material. The smallest UC is composed by a brick and half of its surrounding joints, the former assumed to behave elastically while the latter considered with an elastoplastic softening response. The governing equations at the macroscopic level are formulated in the framework of finite element method while the Meshless Meth…

A Smoothed Particle Image Reconstruction method

2010

Many image processing techniques work with scattered data distribution usually employing grid based methods leading to numerical problems. To address this issue, a numerical method avoiding mesh generation can be used. Such a method performs an integral representation by means of a smoothing kernel function and, in the discrete formulation, involves domain particles. In this paper the meshless Smoothed Particle Hydrodynamics method is proposed in the Image Reconstruction context and a new computational strategy called Smoothed Particle Image Reconstruction is presented; the new method is based on a scatter approach and several innovative ideas are introduced in order to improve the computat…