Paulo Sollero

Dual reciprocity boundary element method in Laplace domain applied to anisotropic dynamic crack problems

In this paper the dual reciprocity boundary element method in the Laplace domain for anisotropic dynamic fracture mechanic problems is presented. Crack problems are analyzed using the subregion technique. The dynamic stress intensity factors are computed using traction singular quarter-point elements positioned at the tip of the crack. Numerical inversion from the Laplace domain to the time domain is achieved by the Durbin method. Numerical examples of dynamic stress intensity factor evaluation are considered for symmetric and non-symmetric problems. The influence of the number of Laplace parameters and internal points in the solution is investigated.

Free vibration analysis of anisotropic material structures using the boundary element method

This paper presents a formulation for the analysis of free vibration in anisotropic structures using the boundary element method. The fundamental solution for elastostatic is used and the inertial terms are treated as body forces providing domain integrals. The dual reciprocity boundary element method is used to reduce domain integrals to boundary integrals. Mode shapes and natural frequencies for free vibration of orthotropic structures are obtained and compared with finite element results showing good agreement.

Structural shape optimization of bonded joints using the ESO method and a honeycomb-like mesh

This work presents an application of the evolutionary structural optimization (ESO) method to optimize two of the most common bonded joints – the single lap joint and the double lap joint. The ESO method was used to shape the adherends contour to reduce peak stresses at the overlap ends. The shape optimization was performed under a von Mises rejection criterion. The von Mises stress was evaluated using the finite element model for both types of joints. It is proposed here to utilize a honeycomb-like mesh using hexagonal elements to minimize stress concentration problem. Additionally, the use of a honeycomb mesh in the ESO method led to a smoother adherend contour. Numerical results show how the stress distributions for both shear and peel stresses are improved after the application of this optimization method.

Fast BEM multi-domain approach for the elastostatic analysis of short fibre composites

Abstract Composite materials are usually treated as homogeneous when carrying out structural design. However, failure in these materials often originated at their heterogeneous microstructure or constituents; hence, the different materials should be considered in the analysis. The use of composite materials has increased considerably over the years due to their relative superior properties. The accurate determination of their mechanical properties and behaviour is thus of great practical significance. The Boundary Element Method (BEM) has demonstrated to be a powerful computational technique for the analysis of many physical and engineering problems. The present work deals with the use of the multi-domain BEM to obtain a more appropriate characterisation of fibre–matrix composites. The generally anisotropic fundamental solution based on a double-Fourier series is employed together with a fast BEM approach, namely, the Adaptive Cross Approximation (ACA) technique. The ACA technique is aimed at speeding up the process required to generate the BEM matrices. Some numerical examples are presented to demonstrate its applicability. The present work is a precursor to treating problems involving anisotropic inclusions in general composites.