High-order quasi-static finite element computations in space and time with application to finite strain viscoelasticity

  • Authors:
  • Torben Netz;Ahmad-Wahadj Hamkar;Stefan Hartmann

  • Affiliations:
  • -;-;-

  • Venue:
  • Computers & Mathematics with Applications
  • Year:
  • 2013

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Abstract

On the one hand, high-order quasi-static finite elements have been developed on the basis of isogeometric analysis or hierarchical shape functions based on integrated Legendre-polynomials, which display favorable behavior in comparison to linear element formulations. If we consider constitutive models of evolutionary-type such as elastoplasticity, viscoplasticity or viscoelasticity, only first order methods are employed to integrate the ordinary-differential equations at the Gauss-point level, leading to errors caused by the time-integration. On the other hand, high-order time integration methods have been devised to treat the resulting system of differential-algebraic equations (DAE-system) following the spatial discretization. This, however, is only done using spatial discretizations with linear or quadratic h-elements based on Lagrange polynomials or related mixed element formulations. In this article both approaches are combined using a p-version finite element approach on the basis of hierarchical shape functions and the resulting DAE-system is solved by means of high-order one-step methods. The first step in this treatise is to apply stiffly accurate, diagonally-implicit Runge-Kutta methods combined with the Multilevel-Newton algorithm. Since the computational outlay for computing the tangential stiffness matrix is very high in the case of p-version finite elements, Rosenbrock-type methods are applied as well, which lead to a completely iteration-free technique. We then compare the two approaches. The next step is to investigate three-dimensional examples showing the properties on the basis of a constitutive model in finite strain viscoelasticity.