17 research outputs found
Effect of spatially varying material properties on the post-buckling behaviour of composite panels utilising geodesic stochastic fields
The post-buckling behaviour of panels can be very sensitive to imperfections
or variations in materials or geometry. This paper presents an
ecient numerical model to calculate the eects of material stiffness
variations on the non-linear response of a structure. This is done by
first defining a geodesic mesh on which a unit variance random field is
generated. This field uses the true geodesic distance on the structure to
calculate how points in the field should be correlated. The fields generated
are projected onto a 3D structural mesh which is used for assembly and
post-processing of the structural model. The structural model, based on
the Unified Formulation is capable of accurate non-linear calculations of
both straight and curved elements. Baseline results generated using the
implementation are compared to those in literature, and verified using
Abaqus. Random material variations are then applied to the structure
in a Monte Carlo analysis. The analyses show that the local variation
of stiffness can have a variety of effects on the non-linear response of
structures. Aside from the change of mean stiffness causing a change in
bifurcation or limit point load, the different stiffness distributions can
affect and trigger competing buckling modes and post-buckling modes
and affect their corresponding post-buckling load-deflection paths
A minimalistic approach for fast computation of geodesic distances on triangular meshes
The computation of geodesic distances is an important research topic in
Geometry Processing and 3D Shape Analysis as it is a basic component of many
methods used in these areas. In this work, we present a minimalistic parallel
algorithm based on front propagation to compute approximate geodesic distances
on meshes. Our method is practical and simple to implement and does not require
any heavy pre-processing. The convergence of our algorithm depends on the
number of discrete level sets around the source points from which distance
information propagates. To appropriately implement our method on GPUs taking
into account memory coalescence problems, we take advantage of a graph
representation based on a breadth-first search traversal that works
harmoniously with our parallel front propagation approach. We report
experiments that show how our method scales with the size of the problem. We
compare the mean error and processing time obtained by our method with such
measures computed using other methods. Our method produces results in
competitive times with almost the same accuracy, especially for large meshes.
We also demonstrate its use for solving two classical geometry processing
problems: the regular sampling problem and the Voronoi tessellation on meshes.Comment: Preprint submitted to Computers & Graphic
ZerNet: Convolutional Neural Networks on Arbitrary Surfaces via Zernike Local Tangent Space Estimation
In this paper, we propose a novel formulation to extend CNNs to
two-dimensional (2D) manifolds using orthogonal basis functions, called Zernike
polynomials. In many areas, geometric features play a key role in understanding
scientific phenomena. Thus, an ability to codify geometric features into a
mathematical quantity can be critical. Recently, convolutional neural networks
(CNNs) have demonstrated the promising capability of extracting and codifying
features from visual information. However, the progress has been concentrated
in computer vision applications where there exists an inherent grid-like
structure. In contrast, many geometry processing problems are defined on curved
surfaces, and the generalization of CNNs is not quite trivial. The difficulties
are rooted in the lack of key ingredients such as the canonical grid-like
representation, the notion of consistent orientation, and a compatible local
topology across the domain. In this paper, we prove that the convolution of two
functions can be represented as a simple dot product between Zernike polynomial
coefficients; and the rotation of a convolution kernel is essentially a set of
2-by-2 rotation matrices applied to the coefficients. As such, the key
contribution of this work resides in a concise but rigorous mathematical
generalization of the CNN building blocks