Browsing by Author "Bernardo, G. M. S."
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- Functionally graded particulate composite plates: a dydactic case studyPublication . Costa, D. M. S.; Bernardo, G. M. S.; Loja, AméliaThis work is part of an educational symbolic platform which was designed to aid and promote the learning of the mechanical behaviour of thin, simply supported rectangular plates. The integration of such simulation tools into the teaching process as an assisting tool can be an additional factor to contribute for a successful competences achievement on this subject. The present case study is focused on the deflection analysis of a functionally graded particulate composite plate submitted to a user-defined transverse loading.
- Optimization of structures modeled with a Meshfree approachPublication . Bernardo, G. M. S.; Loja, AméliaRadial basis functions are being used in different scientific areas in order to reproduce the geometrical modeling of an object/structure, as well as to predict its behavior. Due to its characteristics, these functions are well suited for meshfree modeling of physical quantities, which for instances can be associated to the data sets of 3D laser scanning point clouds. In the present work the geometry of a structure is modeled by using multiquadric radial basis functions, and its configuration is further optimized in order to obtain better performances concerning to its static and dynamic behavior. For this purpose the authors consider the particle swarm optimization technique. A set of case studies is presented to illustrate the adequacy of the meshfree model used, as well as its link to particle swarm optimization technique. © 2014 IEEE.
- Reconstruction and analysis of hybrid composite shells using meshless methodsPublication . Bernardo, G. M. S.; Loja, AméliaThe importance of focusing on the research of viable models to predict the behaviour of structures which may possess in some cases complex geometries is an issue that is growing in different scientific areas, ranging from the civil and mechanical engineering to the architecture or biomedical devices fields. In these cases, the research effort to find an efficient approach to fit laser scanning point clouds, to the desired surface, has been increasing, leading to the possibility of modelling as-built/as-is structures and components’ features. However, combining the task of surface reconstruction and the implementation of a structural analysis model is not a trivial task. Although there are works focusing those different phases in separate, there is still an effective need to find approaches able to interconnect them in an efficient way. Therefore, achieving a representative geometric model able to be subsequently submitted to a structural analysis in a similar based platform is a fundamental step to establish an effective expeditious processing workflow. With the present work, one presents an integrated methodology based on the use of meshless approaches, to reconstruct shells described by points’ clouds, and to subsequently predict their static behaviour. These methods are highly appropriate on dealing with unstructured points clouds, as they do not need to have any specific spatial or geometric requirement when implemented, depending only on the distance between the points. Details on the formulation, and a set of illustrative examples focusing the reconstruction of cylindrical and double-curvature shells, and its further analysis, are presented.
- Reconstruction of surfaces from unstructured points clouds, using compactly-supported radial basis functionsPublication . Bernardo, G. M. S.; Loja, AméliaThe need for a relevant viable approach to fit point clouds obtained by 3D laser scanning, to a desirable surface, has been object ofa substantial research effort and progresso in the past two decades in a wide range of scientific and technological fields. However, this task is far from being a trivial task. First, because of the randomness of the sampled points obtained, which in most cases count with additional noise points. Secondly, in point clouds it is frequent to find lacks ofdata, leading to the existence ofholes in the surface. As far as it is possible to know, all the methods used to achieve the fitting surfaces, present diferente undesirable behaviours, under different conditions. In the present work we present a hybrid method to reconstruct the surfaces associated to synthetic point clouds randomly generated. Parametric studies are carried out to illustrate and characterize the performance ofthe different techniques implemented..
- A study on the structural behaviour of FGM plates static and free vibrations analysesPublication . Bernardo, G. M. S.; Damásio, F. R.; Silva, T. A. N.; Loja, AméliaFunctionally graded materials are characterised by a determined spatial composition variation of their phases’ constituents, which enable for a closer suitability of the material properties to the desired mechanical behaviour. Concerning to the engineered construction of these materials, they can be thought as being achieved by considering a continuous variation of their phases and thus of their properties, or by considering a discrete stacking of a sufficient number of layers, in order to ensure a less abrupt variation profile of their properties. Also, depending on the nature of the applications, it may be important to consider a sandwich configuration, where the three-layered constitution may correspond to a functional requisite. With the present work, these two situations will be studied, considering different methodologies based either on a meshless method or on different approaches based on the finite element method. A comparative study of the performance and adequacy of the developed models is carried out through a set of illustrative cases focused on the study of static and free vibrations behaviour of plate structures.
- A symbolic simulator platform for the static analysis of thin platesPublication . Costa, D. M. S.; Bernardo, G. M. S.; Loja, AméliaThe integration of symbolic capabilities into a simulation platform devoted to the analysis of thin plates can provide a greater flexibility in the learning process as it enables to incorporate, to experiment and simulate more complex and user-defined characteristics. With the present work one has built a symbolic simulator for the study of the mechanical behaviour of thin plates. These plates, with a rectangular/square basis geometric configuration, are simply supported along its four edges, and can be made from homogeneous or non-homogeneous materials. The capabilities of this platform are briefly illustrated through an illustrative case study.
- Towards and expeditious as-is surface reconstructionPublication . Bernardo, G. M. S.; Rodrigues, José Alberto; Loja, AméliaConservation and rehabilitation of structures such as urban buildings and heritage requires a growing effort on the establishment of sufficiently comprehensive documentation concerning the time evolution of these structures’ characteristics and health condition. These documentation archives and databases should be much more than just a collection of structure’s design plans, and desirably they should contain information about the as-built and as-is states of a certain structure. Due to the technological evolution of data acquisition systems, 3D laser scanning points’ clouds became an important data source that enables the subsequent representation of 3D surface’s geometries, and thus the constitution of data repositories. However, it is known that the volume of data obtained, can be enormous and the computation time to process it, a heavy task. The present work proposes an expeditious, continuous processing methodology that aims in a first step the generation of a points’ structured grid and its associated triangle structured mesh by defining an injective function from a virtual surface onto the surface’s cloud points. The additional possibility of selecting the virtual grid dimension to be used, enable representations with diferente levels of detail. In a second step, the resulting structured grids are used to reconstruct the corresponding surfaces by considering compactly-supported radial basis functions. The main contribution of this work is thus related to the proposal of an expeditious integrated processing methodology of points’ clouds. A set of case studies are presented to illustrate the performance of the present integrated methodology.