Search results for " method"
showing 10 items of 10455 documents
Coupled VEM–BEM Approach for Isotropic Damage Modelling in Composite Materials
2023
Numerical prediction of composite damage behaviour at the microscopic level is still a challenging engineering issue for the analysis and design of modern materials. In this work, we document the application of a recently developed numerical technique based on the coupling between the virtual element method (VEM) and the boundary element method (BEM) within the framework of continuum damage mechanics (CDM) to model the in-plane damage evolution characteristics of composite materials. BEM is a widely adopted and efficient numerical technique that reduces the problem dimensionality due to its underlying formulation. It substantially simplifies the pre-processing stage and decreases the compu…
Fast Hierarchical Boundary Element Method for Large Scale 3-D Elastic Problems
2010
This chapter reviews recent developments in the strategies for the fast solution of boundary element systems of equations for large scale 3D elastic problems. Both isotropic and anisotropic materials as well as cracked and uncracked solids are considered. The focus is on the combined use the hierarchical representation of the boundary element collocation matrix and iterative solution procedures. The hierarchical representation of the collocation matrix is built starting from the generation of the cluster and block trees that take into account the nature of the considered problem, i.e. the possible presence of a crack. Low rank blocks are generated through adaptive cross approximation (ACA) …
Structural Health Monitoring of delaminated composite structures by the Boundary Element method
2012
Structural Health Monitoring (SHM) for composite materials is becoming a primary task due to their extended use in safety critical applications. Different methods, based on the use of piezoelectric transducers, strain memory alloys as well as of fibre optics, has been successfully proposed to detect and monitor damage in composite structural components with particular attention focused on delamination cracks. In the present paper a Structural Health Monitoring model based on the use of piezoelectric sensors, already proposed by the authors for isotropic damaged components, is extended to delaminated composite structures. The dynamic behavior of the host damaged structure and the bonded piez…
A HYBRID VEM/BEM NUMERICAL TECHNIQUE FOR SIMULATING DAMAGE IN COMPOSITE MATERIALS
2021
Composite materials are nowadays widely used in the aerospace sector both for primary and secondary structures for their high mechanical properties and the ability to model them according to project needs. Therefore, accurately predicting material behaviour when subjected to operating loads is extremely important in making the design process more efficient. For this purpose, computational approaches based on continuum damage mechanics have been largely used to study the progressive loss of material integrity due to the propagation and coalescence of microscopic defects. In this contribution, a recently developed hybrid computational technique, which combines the Virtual Element Method (VEM)…
Coupling BEM and VEM for the Analysis of Composite Materials with Damage
2021
Numerical tools which are able to predict and explain the initiation and propagation of damage at the microscopic level in heterogeneous materials are of high interest for the analysis and design of modern materials. In this contribution, we report the application of a recently developed numerical scheme based on the coupling between the Virtual Element Method (VEM) and the Boundary Element Method (BEM) within the framework of continuum damage mechanics (CDM) to analyze the progressive loss of material integrity in heterogeneous materials with complex microstructures. VEM is a novel numerical technique that, allowing the use of general polygonal mesh elements, assures conspicuous simplific…
Unsteady Separation and Navier-Stokes Solutions at High Reynolds Numbers
2010
We compute the numerical solutions for Navier-Stokes and Prandtl’s equations in the case of a uniform bidimensional flow past an impulsively started disk. The numerical approx- imation is based on a spectral methods imple- mented in a Grid environment. We investigate the relationship between the phenomena of unsteady separation of the flow and the exponential decay of the Fourier spectrum of the solutions. We show that Prandtl’s solution develops a separation singularity in a finite time. Navier-Stokes solutions are computed over a range of Reynolds numbers from 3000 to 50000. We show that the appearance of large gradients of the pressure in the stream- wise direction, reveals that the visc…
Application of dual boundary element method in active sensing
2013
In this paper, a boundary element method (BEM) for the dynamic analysis of 3D solid structures with bonded piezoelectric transducers is presented. The host structure is modelled with BEM and the piezoelectric transducers are formulated using a 3D semi-analytical finite element approach. The elastodynamic analysis of the entire structure is carried out in Laplace domain and the response in time domain is obtained by inverse Laplace transform. The BEM is validated against established finite element method (FEM).
Special Splines of Exponential Type for the Solutions of Mass Transfer Problems in Multilayer Domains
2016
We consider averaging methods for solving the 3-D boundary-value problem of second order in multilayer domain. The special hyperbolic and exponential type splines, with middle integral values of piece-wise smooth function interpolation are considered. With the help of these splines the problems of mathematical physics in 3-D with piece-wise coefficients are reduced with respect to one coordinate to 2-D problems. This procedure also allows to reduce the 2-D problems to 1-D problems and the solution of the approximated problemsa can be obtained analytically. In the case of constant piece-wise coefficients we obtain the exact discrete approximation of a steady-state 1-D boundary-value problem.…
An investigation of thermal behaviour of brake disk pad assembly with Ansys
2021
Abstract The brake disk is a key part of the braking mechanism, the task of it is to slow or stop the vehicle's wheels, on the one side, while the heat produced during the process is dissipated. In this regard, the brake pads are pressed by mechanical strength on the surface of the brake disks. This study aims to develop a model of a disk brake by use of CATIA V5, on the model, finite element analysis (FEA) done by ANSYS 19 then compare it to the findings gained by the original tests. A computational thermo-mechanical study was conducted on this research by use of ANSYS software for disk brake mounting inside a hydraulic brake system. This study is designed to provide insight into the heat …
The use of stereotaxic cytology in the diagnosis of non-palpable breast lesions. Personal experience
1999
Background and aims. The increasingly frequent use of mammography for the early diagnosis of breast cancer and the consequent identification of mammary lesions at a preclinical stage raises the fundamental problem of the differential diagnosis between non-suspected non-palpable lesions (NPL) which can therefore be monitored over time and suspected NPL or definite carcinoma requiring histological confirmation and surgical biopsy. The diagnostic accuracy of mammography alone is not sufficiently high to differentiate benign lesions from malignant or strongly suspected ones. The use of surgical biopsy in the event of suspected NPL could be significantly reduced by the use of stereotaxic cytolog…