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Interrogation of spline surfaces with application to isogeometric design and analysis of lattice-skin structures

Accepted version
Peer-reviewed

Type

Article

Change log

Authors

Xiao, X 
Sabin, M 

Abstract

A novel surface interrogation technique is proposed to compute the intersection of curves with spline surfaces in isogeometric analysis. The intersection points are determined in one-shot without resorting to a Newton-Raphson iteration or successive refinement. Surface-curve intersection is required in a wide range of applications, including contact, immersed boundary methods and lattice-skin structures, and requires usually the solution of a system of nonlinear equations. It is assumed that the surface is given in form of a spline, such as a NURBS, T-spline or Catmull-Clark subdivision surface, and is convertible into a collection of B'ezier patches. First, a hierarchical bounding volume tree is used to efficiently identify the B'ezier patches with a convex-hull intersecting the convex-hull of a given curve segment. For ease of implementation convex-hulls are approximated with k-dops (discrete orientation polytopes). Subsequently, the intersections of the identified B'ezier patches with the curve segment are determined with a matrix-based implicit representation leading to the computation of a sequence of small singular value decompositions (SVDs). As an application of the developed interrogation technique the isogeometric design and analysis of lattice-skin structures is investigated. The skin is a spline surface that is usually created in a computer-aided design (CAD) system and the periodic lattice to be fitted consists of unit cells, each containing a small number of struts. The lattice-skin structure is generated by projecting selected lattice nodes onto the surface after determining the intersection of unit cell edges with the surface. For mechanical analysis, the skin is modelled as a Kirchhoff-Love thin-shell and the lattice as a pin-jointed truss. The two types of structures are coupled with a standard Lagrange multiplier approach.

Description

Keywords

Isogeometric analysis, Splines, Interrogation, Implicit geometry, Algebraic geometry, 3d printing

Journal Title

Computer Methods in Applied Mechanics and Engineering

Conference Name

Journal ISSN

0045-7825
1879-2138

Volume Title

351

Publisher

Elsevier BV