Isogeometric analysis of laminated composite shells

Isogeometric analysis (IGA) has recently received much attention in the computational mechanics community. The basic idea is to use splines, which are the functions commonly used in computer-aided design to describe the geometry, as the basis function for the analysis.

PhD candidate: Saman Hosseini
Daily supervisor: Dr. ir. Joris.J.C. Remmers
Project supervisor: Prof. dr. ir. R. De Borst
Financing: MAAXIMUS project, 7th framework programme 

A main advantage of isogeometric analysis is that the functions used for the representation of the geometry are employed directly for the analysis. Indeed, the exact parametrization of the geometry can have benefits for the numerical simulation of shell structures, which can be very sensitive to imperfections in the geometry.

A further benefit of basis functions that possess a higher degree of continuity is that the computation of stresses is vastly improved. In shell analysis this can be particularly important when materially non-linear phenomena such as damage, or delamination, which can occur in laminated spatial structures, are included in the analysis. In the latter case the computation of an accurate three-dimensional stress field becomes mandatory, and solid-like shell elements become an obvious choice. A solid-like shell element (SLSBEZ) based on the isogeometric concept has been developed. The work utilizes NURBS basis functions to construct the mid-surface of the shell.

A demonstration of the formulation has been shown for a pinched cylinder which is loaded by two centrally located, diametrically opposed point forces, pushing inwards. Using local mesh refinements local effects such as wrinkles and stress concentrations can be accurately represented.